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Cited by 345Skin Protection and AgingPhytochemicals and Antioxidant Activitiesmelanin and skin pigmentation

Bioactive Compounds for Skin Health: A Review

Open access
Michalak, Monika, Pierzak, Monika, Kręcisz, Beata, Suliga, Edyta·2021·Nutrients
DOI 10.3390/nu13010203PMC PMC7827176
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Abstract

Human skin is continually changing. The condition of the skin largely depends on the individual’s overall state of health. A balanced diet plays an important role in the proper functioning of the human body, including the skin. The present study draws attention to bioactive substances, i.e., vitamins, minerals, fatty acids, polyphenols, and carotenoids, with a particular focus on their effects on the condition of the skin. The aim of the study was to review the literature on the effects of bioactive substances on skin parameters such as elasticity, firmness, wrinkles, senile dryness, hydration and color, and to define their role in the process of skin ageing.

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Written from the paper’s full text.

TL;DR

This narrative review summarizes evidence on dietary and topical bioactive compounds—vitamins A, C, E; minerals selenium, zinc, copper, silicon; omega-3/6 fatty acids; polyphenols; and carotenoids—for skin health and ageing. It concludes that these substances may protect against oxidative and UV damage and improve hydration, elasticity, wrinkles, pigmentation, and barrier function, though evidence is mixed and drawn from heterogeneous in vitro, animal, and human studies.

Key findings

  • The review covers vitamins A, C, E; selenium, zinc, copper, silicon; omega-3/6 fatty acids; polyphenols; and carotenoids, and reports effects on elasticity, firmness, wrinkles, senile dryness, hydration, color, and skin ageing. It concludes that oral antioxidants can supplement chemical and physical UV filters and that healthy dietary habits may improve skin appearance, delay ageing, and reduce skin cancer risk.
  • Vitamin C concentration in skin is higher than in other human tissues: 6–64 mg/100 g wet weight in the epidermis and 3–13 mg/100 g in the dermis; higher vitamin C intake was associated with a reduced likelihood of wrinkled appearance and senile dryness. Topically applied retinoids reduce skin discoloration and pigmentation by about 60%; a retinol formulation improved tensile properties and contours after 12 weeks; in mice, retinol esters accounted for 90% of epidermal vitamin A and retinol 10%.
  • Selenium at 30 nM protected young keratinocytes (from 20–30-year-old donors) against UVA, while 240 nM was required for old keratinocytes (from 60–70-year-old donors); high serum selenium was associated with an approximately 60% decrease in basal cell carcinoma and squamous cell carcinoma incidence, but other studies found no significant effect. A 0.1% copper–zinc malonate cream applied topically for 6 weeks significantly reduced wrinkles, and a 10% zinc sulphate solution applied topically twice daily for 2 months significantly reduced MASI scores.
  • In a 40-woman green tea polyphenol trial, 10% green tea cream plus 300 mg twice-daily oral supplementation produced significant histological improvement in elastic tissue but no significant clinical changes; in mice, green tea polyphenols inhibited UVB-induced MMP-2 (67%), MMP-3 (63%), MMP-7 (62%), and MMP-9 (60%). Astaxanthin 2 mg/day plus collagen hydrolysate 3 g/day improved barrier integrity, reduced TEWL, and increased procollagen type I mRNA; lutein 10 mg plus zeaxanthin 2 mg daily for 12 weeks improved skin appearance and lightened skin tone.

Methods

  • Design: narrative literature review aimed at presenting the effects of bioactive substances on skin parameters such as wrinkled appearance, elasticity, firmness, senile dryness, hydration, and color, and their role in skin ageing.
  • Data: literature on selected vitamins, minerals, fatty acids, polyphenols, and carotenoids; the paper does not report a systematic search strategy, databases, inclusion/exclusion criteria, or date range.
  • Analysis: narrative synthesis of cited in vitro, animal, and human studies; no meta-analysis or formal quality assessment is described.

Limitations

  • Stated limitations: Not stated in the paper.
  • Evident from the text: the review is narrative and lacks a systematic search, inclusion criteria, and quality appraisal, so selection and synthesis may be non-exhaustive or biased.
  • Evident from the text: evidence is heterogeneous and sometimes contradictory—e.g., vitamin E results range from improvement to no effect, selenium and skin cancer findings are controversial, the green tea clinical trial showed no significant clinical changes, and β-carotene did not significantly reduce new skin cancers; many cited studies are small or use specific populations, limiting generalizability.

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Integrity signals

Registry

Crossref · 10.3390/nu13010203

Cites

238 of 238 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

0 of 358 cited sources checked · 0 supported · 0 flagged

  • Premisecitation

    The anti-ageing effects of retinoids are mediated by epidermal keratinocytes, dermal endothelial cells and fibroblasts.

    “The anti-ageing effects of retinoids are mediated by three major types of skin cells: epidermal keratinocytes, dermal endothelial cells and fibroblasts [38].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Shao, 2017, Molecular basis of retinol anti-ageing properties in naturally aged human skin in vivo, Int. J. Cosmet. Sci. source

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  • Premisecitation

    After penetrating the epidermis, retinoids play a role in the release of transcription and growth factors.

    “After penetrating the epidermis, retinoids play a role in the release of transcription and growth factors.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [28] Sorg, 2005, Proposed mechanisms of action for retinoid derivatives in the treatment of skin aging, J. Cosmetic. Dermato. source

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    • cites [34] Oliveira, L.M., Teixeira, F.M.E., and Sato, M. (2018). N Impact of retinoic acid on immune cells and inflammatory diseases. Mediat. Inflamm. source

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    • cites [35] Ferreira, 2020, Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine, Nat. Commun. source

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  • Premisecitation

    Some dietary botanicals could be useful supplements for mature skin care due to their antimutagenic, antioxidant and free-radical-scavenging properties.

    “Due to their ability to protect the skin from harmful UV-induced effects through their antimutagenic, antioxidant and free-radical-scavenging properties, some dietary botanicals could be useful supplements for mature skin care [23,24].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [23] Reuter, 2010, Botanicals in dermatology: An evidence-Based review, Am. J. Clin. Dermatol.

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    • cites [24] Tungmunnithum, D., Thongboonyou, A., Pholboon, A., and Yangsabai, A. (2018). Flavonoids and other phenolic compounds from medicinal plants for pharmaceutical and medical aspects: An overview. Medicines, 5. source

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  • Premisecitation

    Activation of fibroblast production is stimulated through the TGF-β/CTGF pathway, the major regulator of ECM homeostasis.

    “The activation of fibroblast production is stimulated through the TGF-β/CTGF pathway, the major regulator of ECM homeostasis [38].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Shao, 2017, Molecular basis of retinol anti-ageing properties in naturally aged human skin in vivo, Int. J. Cosmet. Sci. source

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  • Premisecitation

    Retinoids are responsible for the renewal of the epidermis through exfoliation of dead cells in the stratum corneum and proliferation of live cells in the epidermal layers.

    “They are responsible for the renewal of the epidermis through their active role in the exfoliation of dead cells in the stratum corneum and the proliferation of live cells in the epidermal layers [28,34,35].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [28] Sorg, 2005, Proposed mechanisms of action for retinoid derivatives in the treatment of skin aging, J. Cosmetic. Dermato. source

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    • cites [34] Oliveira, L.M., Teixeira, F.M.E., and Sato, M. (2018). N Impact of retinoic acid on immune cells and inflammatory diseases. Mediat. Inflamm. source

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    • cites [35] Ferreira, 2020, Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine, Nat. Commun. source

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  • Classified as probably not a substantial claim. 19
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  • The quote only partly states this claim. 2

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    Premisecitation

    A balanced diet plays an important role in the proper functioning of the human body, including the skin.

    “A balanced diet plays an important role in the proper functioning of the human body, including the skin.”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [14] Kaimal, 2010, Diet in dermatology: Revisited, IndianJ. Dermatol. Venereol. Leprol. source

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    • cites [15] Boelsma, 2003, Human skin condition and its associations with nutrient concentrations in serum and diet, Am. J. Clin. Nutr. source

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    • cites [16] Divya, 2015, Role of diet in dermatological conditions, J. Nutr. Food Sci.

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    • cites [17] Navratil, 2014, The impact of diet on common skin disorders, J. Nutr. Ther. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Skin ageing is influenced by two mechanisms: intrinsic (genetic, chronological) ageing and extrinsic ageing (photoaging) caused by environmental factors including UV radiation, environmental pollution and cigarette smoke.

    “One of the most common dermatological and cosmetic concerns is skin ageing: a natural, complex process influenced by two mechanisms—intrinsic (genetic, chronological) ageing resulting from the passage of time, and extrinsic ageing (photoaging), caused by environmental factors (including UV radiation, environmental pollution and cigarette smoke) [5,6,7,8].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [5] Bauer, 2014, Reactive molecule species and antioxidative mechanisms in normal skin and skin aging, Skin Pharmacol. Physiol. source

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    • cites [6] Dahmane, 2012, Intrinsic skin aging: The role of oxidative stress, Acta Dermatovener.

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    • cites [7] Nishigori, 2003, Photoaging and oxidative stress, Exp. Dermatol. source

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    • cites [8] Binic, I., Lazarevic, V., Ljubenovic, M., Mojsa, J., and Sokolovic, D. (2013). Skin ageing: Natural weapons and strategies. Evid. Based Complement. Alternat. Med. source

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    Premisecitation

    Both intrinsic and extrinsic skin ageing processes are associated with increased reactive oxygen species and oxidative stress in the skin.

    “The two processes overlap and are closely linked to increased reactive oxygen species (ROS) and oxidative stress in the skin [9].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [9] Poljšak, B., and Dahmane, R.G. (2012). Free radicals and extrinsic skin aging. Dermatol. Res. Pract., 1–10. source

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    Premisecitation

    Vitamin A promotes the compaction of the stratum corneum and deposition of GAGs in the stratum corneum and intercellular spaces in the epidermis.

    “Moreover, vitamin A promotes the compaction of the stratum corneum and deposition of GAGs in the stratum corneum and intercellular spaces in the epidermis [40].”
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    • cites [40] Bagatin, 2009, Cosmeceuticals vitamins, Clin. Dermatol. source

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    Premisecitation

    Application of all-trans-retinol on normal human skin induced epidermal thickening and increased mRNA expression of cellular retinoic acid binding protein and cellular retinol binding protein.

    “A study conducted by Kang et al. showed that the application of all-trans-retinol on normal human skin induced epidermal thickening and increased the mRNA expression of cellular retinoic acid binding protein and cellular retinol binding protein [41].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] Kang, 1995, Application of retinol to human skin in vivo induces epidermal hyperplasia and cellular retinoid binding proteins characteristic of retinoic acid but without measurable retinoic acid levels or irritation, J. Investig. Dermatol. source

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    Premisecitation

    Retinoids and all biologically active forms of vitamin A promote remodeling of reticulin fibers and synthesis of a new capillary network in the dermis.

    “Retinoids and all biologically active forms of vitamin A also promote the remodeling of reticulin fibers and synthesis of a new capillary network in the dermis.”
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    • cites [35] Ferreira, 2020, Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine, Nat. Commun. source

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    • cites [42] Varani, 2000, Vitamin A antagonizes decreased cell growth and elevated collagen degrading matrix metaloproteinases and stimulates collagen accumulation in naturally aged human skin, J. Investig. Dermatol. source

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    Premisecitation

    Retinoids inhibit cell division during excessive proliferation and activate it when the process is too slow.

    “Retinoids are a group of chemical compounds that inhibit cell division during excessive proliferation and activate it when the process is too slow.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [28] Sorg, 2005, Proposed mechanisms of action for retinoid derivatives in the treatment of skin aging, J. Cosmetic. Dermato. source

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    • cites [34] Oliveira, L.M., Teixeira, F.M.E., and Sato, M. (2018). N Impact of retinoic acid on immune cells and inflammatory diseases. Mediat. Inflamm. source

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    • cites [37] Chaudhuri, 2014, Bakuchiol: A retinol-like functional compound revealed by gene expression profiling and clinically proven to have anti-aging effects, Int. J. Cosmet. Sci. source

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    Premisecitation

    Retinoids protect collagen against destruction induced by MMPs and enhance synthesis of tissue inhibitors of metalloproteinases (TIMPs).

    “Retinoids protect collagen against the destruction induced by MMPs, as well as enhancing the synthesis of tissue inhibitors of metalloproteinases (TIMPs) [32,42].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [32] Zasada, 2019, Retinoids: Active molecules influencing skin structure formation in cosmetic and dermatological treatments, Postepy Dermatol. Alergol. source

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    • cites [42] Varani, 2000, Vitamin A antagonizes decreased cell growth and elevated collagen degrading matrix metaloproteinases and stimulates collagen accumulation in naturally aged human skin, J. Investig. Dermatol. source

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    Premisecitation

    In mice, retinol esters accounted for 90% of the vitamin A in the epidermis, with retinol making up the remaining 10%.

    “A study in mice by Törmä et al. showed that retinol esters accounted for 90% of the vitamin A in the epidermis, with retinol making up the remaining 10% [39].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] Brunnberg, 1987, Age-related variations in acyl-CoA: Retinol acyltransferase activity and vitamin A concentration in the liver and epidermis of hairless mice, Biochim. Biophys. Acta. source

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    Premisecitation

    Retinoids affect the thickness and color of the skin, regulate sebaceous gland function, limit sebum production, are responsible for hair and nail growth, and influence melanin distribution in the skin.

    “Retinoids also affect the thickness and color of the skin, regulate the function of the sebaceous glands, and limit sebum production, as well as being responsible for hair and nail growth, and also influencing the distribution of melanin in the skin [27,30,35].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [27] Khali, 2017, Retinoids: A journey from the molecular structures and mechanisms of action to clinical uses in dermatology and adverse effects, J. Dermatolog. Treat. source

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    • cites [30] Polcz, 2019, The Role of Vitamin A in Wound Healing, Nutr. Clin. Pract. source

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    • cites [35] Ferreira, 2020, Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine, Nat. Commun. source

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    Premisecitation

    Topical retinol improves the dermal extracellular matrix microenvironment (type I collagen, fibronectin, and elastin) and activates ECM-producing cells in aged skin.

    “Topical retinol improves the dermal extracellular matrix (ECM) microenvironment (type I collagen, fibronectin, and elastin) and activates ECM-producing cells in aged skin [32,38].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [32] Zasada, 2019, Retinoids: Active molecules influencing skin structure formation in cosmetic and dermatological treatments, Postepy Dermatol. Alergol. source

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    • cites [38] Shao, 2017, Molecular basis of retinol anti-ageing properties in naturally aged human skin in vivo, Int. J. Cosmet. Sci. source

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    Interpretationcitation

    This process influences the condition of the connective tissue of the dermis, improving its firmness, hydration and elasticity.

    “This process influences the condition of the connective tissue of the dermis, improving its firmness, hydration and elasticity [35,42].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [35] Ferreira, 2020, Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine, Nat. Commun. source

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    • cites [42] Varani, 2000, Vitamin A antagonizes decreased cell growth and elevated collagen degrading matrix metaloproteinases and stimulates collagen accumulation in naturally aged human skin, J. Investig. Dermatol. source

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    Premisecitation

    Vitamin C significantly curtails lipid oxidation by regenerating fat-soluble vitamin E; it regenerates α-tocopherol from α-tocopherol radicals found in cell membranes and lipoproteins.

    “Although the direct antioxidant protection provided by vitamin C is limited to aqueous compartments, vitamin C significantly curtails lipid oxidation by regenerating fat-soluble vitamin E; it regenerates α-tocopherol from α-tocopherol radicals found in cell membranes and lipoproteins [60].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [60] Jones, 1995, Impact of nutrients on cellular lipid peroxidation and antioxidant defense system, Fundam. Appl. Toxicol. source

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    Premisecitation

    Vitamin C enhances keratinocyte differentiation, reduces differentiation-dependent oxidative stress and maintains the integrity of the skin barrier, which helps prevent water loss from the skin.

    “The vitamin has been shown to enhance keratinocyte differentiation, reduce differentiation-dependent oxidative stress and maintain the integrity of the skin barrier, which in turn helps to prevent water loss from the skin [55,57].”
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    • cites [55] Ponec, 1997, The formation of competent barrier lipids in reconstructed human epidermis requires the presence of vitamin C, J. Investig. Dermatol. source

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    • cites [57] Savini, 2002, Characterization of keratinocyte differentiation induced by ascorbic acid: Protein kinase C involvement and vitamin C homeostasis, J. Investig. Derm. source

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    Premisecitation

    Ascorbate improves the barrier functions of the epidermis and promotes the formation of the cornified cell envelope in normal human epidermal keratinocytes in vitro.

    “Savini et al., in an in vitro study on normal human epidermal keratinocytes, showed that ascorbate improves the barrier functions of the epidermis and promotes the formation of the cornified cell envelope, a specialized structure that protects the body against harmful chemical and physical factors [57].”
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    • cites [57] Savini, 2002, Characterization of keratinocyte differentiation induced by ascorbic acid: Protein kinase C involvement and vitamin C homeostasis, J. Investig. Derm. source

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    Premisecitation

    Retinoids influence the function of melanocytes and the distribution of melanin in the skin, and block the transport of melanin to epidermal cells.

    “Retinoids influence the function of melanocytes and the distribution of melanin in the skin, as well as blocking the transport of melanin to epidermal cells.”
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    • cites [32] Zasada, 2019, Retinoids: Active molecules influencing skin structure formation in cosmetic and dermatological treatments, Postepy Dermatol. Alergol. source

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    Premisecitation

    Vitamin C promotes the formation of the epidermal barrier and collagen in the dermis, protects against skin oxidation, helps to counteract skin ageing, and plays a role in signaling pathways of cell growth and differentiation linked to various skin diseases.

    “Vitamin C promotes the formation of the epidermal barrier and collagen in the dermis, protects against skin oxidation, helps to counteract skin ageing, and plays a role in the signaling pathways of cell growth and differentiation, which are linked to the occurrence of various skin diseases [55,56].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [55] Ponec, 1997, The formation of competent barrier lipids in reconstructed human epidermis requires the presence of vitamin C, J. Investig. Dermatol. source

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    • cites [56] Wang, 2018, Role of Vitamin C in Skin Diseases, Front. Physiol. source

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    Premisecitation

    Retinyl esters present in the epidermis have strong antiphotocarcinogenic properties and protect DNA against damage by UV radiation.

    “The results clearly indicate that retinyl esters present in the epidermis have strong antiphotocarcinogenic properties and protect DNA against damage by UV radiation [44].”
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    • cites [44] Antille, 2003, Vitamin A exerts a photoprotective action in skin by absorbing ultraviolet B radiation, J. Investig. Dermatol. source

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    Premisecitation

    Vitamin C functions as a cofactor of proline and lysine hydroxylases, promotes the expression of collagen genes, and activates the production of collagen mRNA by fibroblasts.

    “It functions as a cofactor of proline and lysine hydroxylases, which are responsible for the tertiary structure of collagen; promotes the expression of collagen genes; and activates the production of collagen mRNA by fibroblasts [50].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [50] Rhie, 2001, Aging-and photoaging-dependent changes of enzymic and nonenzymic antioxidants in the epidermis and dermis of human skin in vivo, J. Investig. Dermatol. source

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    Premisecitation

    Topical vitamin A (retinol) reduced MMP expression and increased fibroblast growth and collagen synthesis in naturally aged, as it did in photoaged, skin.

    “Varani et al. observed that topical vitamin A (retinol) reduced MMP expression and increased fibroblast growth and collagen synthesis in naturally aged, as it did in photoaged, skin [42].”
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    • cites [42] Varani, 2000, Vitamin A antagonizes decreased cell growth and elevated collagen degrading matrix metaloproteinases and stimulates collagen accumulation in naturally aged human skin, J. Investig. Dermatol. source

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    Premisecitation

    Ascorbic acid plays an active role in the proliferation and migration of skin fibroblasts and stimulates the production of collagen and elastin in cultures of fibroblasts.

    “There is scientific evidence that ascorbic acid plays an active role in the proliferation and migration of skin fibroblasts and stimulates the production of collagen and elastin in cultures of fibroblasts [46,49].”
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    • cites [46] 2009, An overview of ascorbic acid biochemistry, J. Fac. Pharm. Ankara.

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    • cites [49] Pullar, 2017, The roles of vitamin C in skin health, Nutrients source

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    Premisecitation

    Vitamin C enhanced the differentiation of rat epidermal keratinocytes cell line in an organotypic culture model, resulting in a stronger stratum corneum, indicating a skin-protective function.

    “Pasonen-Seppanen et al. showed that vitamin C enhanced the differentiation of rat epidermal keratinocytes cell line in an organotypic culture model, resulting in a stronger stratum corneum, which indicates that it has a skin-protective function [58].”
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    • cites [58] Suhonen, 2001, Vitamin C enhances differentiation of a continuous keratinocyte cell line (REK) into epidermis with normal stratum corneum ultrastructure and functional permeability barrier, Histochem. Cell Biol. source

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    Premisecitation

    Vitamin C inhibits melanogenesis with low cytotoxicity, although some studies suggest that the role of vitamin C in inhibiting melanogenesis is very minor.

    “A review of the literature indicates that vitamin C inhibits melanogenesis with low cytotoxicity, although some studies suggest that the role of vitamin C in inhibiting melanogenesis is very minor [67,68,69].”
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    • cites [67] Panich, 2011, Inhibition of UVA-mediated Melanogenesis by Ascorbic Acid through Modulation of Antioxidant Defense and Nitric Oxide System, Arch. Pharm. Res. source

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    • cites [68] Choi, 2010, Effects of vitamin C vs. multivitamin on melanogenesis: Comparative study in vitro and in vivo, Int. J. Dermatol. source

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    • cites [69] Shimada, 2009, Effects of ascorbic acid on gingival melanin pigmentation in vitro and in vivo, J. Periodontol. source

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    Premisecitation

    Supplementation with vitamin C enhances the production of GAGs, promotes the expression of genes coding for antioxidant enzymes and enzymes involved in DNA repair, and inhibits the production of pro-inflammatory cytokines and apoptosis induced by UV radiation or other harmful environmental factors.

    “Supplementation with vitamin C enhances the production of GAGs, promotes the expression of genes coding for antioxidant enzymes and enzymes involved in DNA repair, and inhibits the production of pro-inflammatory cytokines and apoptosis induced by UV radiation or other harmful environmental factors [49].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [49] Pullar, 2017, The roles of vitamin C in skin health, Nutrients source

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    Premisecitation

    Supplementation with selenium does not significantly affect the incidence of basal cell carcinoma or is ineffective in preventing it.

    “However, some researchers have demonstrated that supplementation with Se does not significantly affect the incidence of BCC or is ineffective in preventing it [95,96].”
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    • cites [95] Combos, 1997, Reduction of cancer mortality and incidence by selenium supplementation, Med Klin source

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    • cites [96] Slate, 2003, Selenium supplementation and secondary prevention of nonmelanoma skin cancer in a randomized trial, J. Natl. Cancer. Inst. source

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    Premisecitation

    Alpha-tocopherol decreases the amount of 8-hydroxydeoxyguanosine produced indirectly by reactive oxygen species, so it may reduce ROS-induced DNA damage and help retard the development of skin cancer.

    “Alpha-tocopherol has been shown to decrease the amount of 8-hydroxydeoxyguanosine produced indirectly by reactive oxygen species, so it may reduce ROS-induced DNA damage and thereby help to retard the development of skin cancer [81].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [81] Ichihashi, 1999, The inhibitory effect of DL-alpha-tocopheryl ferulate in lecithin on melanogenesis, Anticancer Res.

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    Premisecitation

    A high serum concentration of selenium is associated with an approximately 60% decrease in the incidence of basal cell carcinoma and squamous cell carcinoma of the skin.

    “Research by Pols et al. indicates that a high serum concentration of selenium is associated with an approximately 60% decrease in the incidence of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) of the skin [94].”
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    • cites [94] Heinen, 2009, Serum antioxidants and skin cancer risk: An 8-year community-based follow-up study, Cancer Epidemiol. Biomark. Prev. source

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    Premisecitation

    A selenium-rich tuna heart extract enhanced collagen synthesis and promoted the proliferation of skin fibroblasts, thus having anti-ageing and anti-wrinkle effects.

    “Kim et al. showed that a selenium-rich tuna heart extract enhanced collagen synthesis and promoted the proliferation of skin fibroblasts, thus having anti-ageing and anti-wrinkle effects [93].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [93] Kim, 2016, Anti-wrinkle effects of a tuna heart H2O fraction on Hs27 human fibroblasts, Int. J. Mol. Med. source

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    Premisecitation

    Selenium is one of the most important trace elements without which the body cannot function properly.

    “Selenium (Se) is one of the most important trace elements without which the body cannot function properly.”
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    • cites [88] Bao, 2011, Selenium in human health and disease, Antioxid. Redox Signal. source

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    Premisecitation

    Selenium occurs in two forms: inorganic (selenates and selenites) and organic (selenomethionine and selenocysteine).

    “It occurs in two forms: inorganic (selenates and selenites) and organic (selenomethionine and selenocysteine) [88].”
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    • cites [88] Bao, 2011, Selenium in human health and disease, Antioxid. Redox Signal. source

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  • May combine two claims.

    Premisecitation

    Alpha-tocopherol inhibits tyrosine hydroxylase activity and suppresses melanogenesis in cultured human melanoma cells and normal human melanocytes.

    “Ichihashi et al., in an in vitro study using cultured human melanoma cells and normal human melanocytes, showed that alpha-tocopherol inhibits tyrosine hydroxylase activity and suppresses melanogenesis [81].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [81] Ichihashi, 1999, The inhibitory effect of DL-alpha-tocopheryl ferulate in lecithin on melanogenesis, Anticancer Res.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Vitamin E displays strong photoprotective, firming, hydrating and anti-ageing properties, as well as improving the elasticity, structure and softness of the epidermis and dermis.

    “Some research also indicates that vitamin E displays strong photoprotective, firming, hydrating and anti-ageing properties, as well as improving the elasticity, structure and softness of the epidermis and dermis [40,82].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [40] Bagatin, 2009, Cosmeceuticals vitamins, Clin. Dermatol. source

      Not checked in the free run.

    • cites [82] Keen, 2016, Vitamin E in dermatology, Indian. Dermatol. Online J. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A combination of vitamin C and other vitamins, including vitamin E, is more effective at reducing melanin than vitamin C alone and can be used for treating skin discoloration, e.g., age spots or melasma.

    “Furthermore, a combination of vitamin C and other vitamins, including vitamin E, is more effective at reducing melanin than vitamin C alone and can be used for treating skin discoloration, e.g., age spots or melasma [50,68].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [50] Rhie, 2001, Aging-and photoaging-dependent changes of enzymic and nonenzymic antioxidants in the epidermis and dermis of human skin in vivo, J. Investig. Dermatol. source

      Not checked in the free run.

    • cites [68] Choi, 2010, Effects of vitamin C vs. multivitamin on melanogenesis: Comparative study in vitro and in vivo, Int. J. Dermatol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Vitamin E protects against lipid peroxidation and slows skin ageing owing to its antioxidant properties and ability to scavenge free radicals and become part of lipid structures.

    “Owing to the antioxidant properties of vitamin E and its ability to scavenge free radicals and become part of lipid structures, it protects against lipid peroxidation and slows skin ageing [80].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [80] Lee, G.Y., and Han, S.N. (2018). The role of Vitamin E in Immunity. Nutrients, 10. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The skin is the third most zinc-abundant tissue in the body, with greater amounts in the epidermis than in the dermis.

    “The skin is the third most Zn-abundant tissue in the body, with greater amounts in the epidermis than in the dermis [99,102].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [99] Ogawa, Y., Kinoshita, M., Shimada, S., and Kawamura, T. (2018). Zinc and skin disorders. Nutrients, 10. source

      Not checked in the free run.

    • cites [102] Michaelsson, 1980, Zinc in epidermis and dermis in healthy subjects, Acta Derm. Venereol. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Selenium supplementation is an important strategy for inhibiting wrinkles because it can reverse ultraviolet light damage and play an anti-ageing role in the skin.

    “Selenium supplementation is an important strategy for inhibiting wrinkles, because it can reverse ultraviolet light damage and play an anti-ageing role in the skin [89,92].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [89] Cai, 2019, Selenium, aging and aging-related diseases, Aging Clin. Exp. Res. source

      Not checked in the free run.

    • cites [92] Favrot, C., Beal, D., Blouin, E., Leccia, M.E., and Roussel, A.M. (2018). Age-dependent protective effect of selenium against UVA irradiation in primary human keratinocytes and the associated DNA repair signature. Oxid. Med. Cell. Longev. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Zinc is an essential microelement with an important role in many physiological processes.

    “Zinc (Zn) is an essential microelement with an important role in many physiological processes [97].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [97] Devi, 2014, Zinc in human health, IOSR-JDMS source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Selenium exhibits strong antioxidant properties and protects against DNA damage.

    “Selenium exhibits strong antioxidant properties and protects against DNA damage [88,89].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [88] Bao, 2011, Selenium in human health and disease, Antioxid. Redox Signal. source

      Not checked in the free run.

    • cites [89] Cai, 2019, Selenium, aging and aging-related diseases, Aging Clin. Exp. Res. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Low doses of selenium (30 nM) provide potent protection against UVA-induced cytotoxicity in young keratinocytes from 20-30-year-old donors, while higher concentrations (240 nM) are required for protective efficacy in old keratinocytes from donors 60-70 years old.

    “Favrot et al. showed that low doses of Se (30 nM) provide potent protection against UVA-induced cytotoxicity in young keratinocytes (from 20–30-year-old donors), while higher concentrations (240 nM) were required for protective efficacy in old keratinocytes (from donors 60–70 years old) [92].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [92] Favrot, C., Beal, D., Blouin, E., Leccia, M.E., and Roussel, A.M. (2018). Age-dependent protective effect of selenium against UVA irradiation in primary human keratinocytes and the associated DNA repair signature. Oxid. Med. Cell. Longev. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Vitamin E, incorporated into the intercellular cement and lipid structures, protects the skin against solar UVB radiation and, thus, against redness and swelling.

    “It is thought that vitamin E, incorporated into the intercellular cement and lipid structures, protects the skin against solar UVB radiation and, thus, against redness and swelling.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [40] Bagatin, 2009, Cosmeceuticals vitamins, Clin. Dermatol. source

      Not checked in the free run.

    • cites [83] Dahiaya, 2006, Cosmeceuticals: A review of their use for aging and photoaged skin, Cosmet. Dermatol.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The available literature concerning the efficacy of the systemic and topical use of vitamin E is extensive, but the results are often contradictory and range from an improvement in skin appearance to no effect at all.

    “The available literature concerning the efficacy of the systemic and topical use of vitamin E is extensive, but the results are often contradictory and range from an improvement in skin appearance to no effect at all [40].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [40] Bagatin, 2009, Cosmeceuticals vitamins, Clin. Dermatol. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Selenium should be supplied to the human body with foods of plant and animal origin.

    “Selenium should be supplied to the human body with foods of plant and animal origin [26,88] (Table 1).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [26] Godswill, 2020, Health benefits of micronutrients (vitamins and minerals) and their associated deficiency diseases: A systematic review, Int. J. Food. Sci.

      Not checked in the free run.

    • cites [88] Bao, 2011, Selenium in human health and disease, Antioxid. Redox Signal. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Selenium is important for skin function, having a protective effect and the ability to scavenge free radicals.

    “The mineral is also important for skin function, having a protective effect and the ability to scavenge free radicals [89].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [89] Cai, 2019, Selenium, aging and aging-related diseases, Aging Clin. Exp. Res. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Zinc affects the immune function of the skin, modulating macrophage and neutrophil functions, phagocytic activity and various inflammatory cytokines.

    “Zinc also affects the immune function of the skin, modulating macrophage and neutrophil functions, phagocytic activity and various inflammatory cytokines [98,99].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [98] Gupta, M., Mahajan, V.K., Mehta, K.S., and Chauhan, P.S. Zinc therapy in dermatology: A review. Dermatol. Res. Pract., 2014. source

      Not checked in the free run.

    • cites [99] Ogawa, Y., Kinoshita, M., Shimada, S., and Kawamura, T. (2018). Zinc and skin disorders. Nutrients, 10. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Zinc stabilizes skin cell membranes and participates in basal cell mitosis and differentiation, while also playing crucial roles in the survival of keratinocytes.

    “It stabilizes skin cell membranes and participates in basal cell mitosis and differentiation [106], while also playing crucial roles in the survival of keratinocytes.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [106] Vollmer, D.L., West, V.A., and Lephart, E.D. (2018). Enhancing skin health: By oral administration of natural compounds and minerals with implications to the dermal microbiome. Int. J. Mol. Sci., 19. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Copper ions reduce the risk of fungal and bacterial infection of minor wounds and cuts, as well as enhancing wound healing.

    “Copper ions reduce the risk of the fungal and bacterial infection of minor wounds and cuts, as well as enhancing wound healing [118].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [118] Borkow, 2014, Using Copper to Improve the Well-Being of the Skin, Curr. Chem. Biol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Copper ions are commonly included in cosmetics, and copper is used as an active component of face creams, including those for the care of mature, tired, dull or oily skin.

    “Copper ions are commonly included in cosmetics. Cu is used as an active component of face creams, including those for the care of mature, tired, dull or oily skin [118,130].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [118] Borkow, 2014, Using Copper to Improve the Well-Being of the Skin, Curr. Chem. Biol. source

      Not checked in the free run.

    • cites [130] Pickart, L., and Margolina, A. (2018). Skin regenerative and anti-cancer actions of copper peptides. Cosmetics, 5. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Copper is a cofactor of superoxide dismutase, an enzyme involved in protecting the skin against the harmful effects of free radicals, and also prevents oxidative damage to cell membranes and lipid peroxidation.

    “It is a cofactor of superoxide dismutase (SOD), an enzyme involved in protecting the skin against the harmful effects of free radicals, and also prevents oxidative damage to cell membranes and lipid peroxidation [118,126].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [118] Borkow, 2014, Using Copper to Improve the Well-Being of the Skin, Curr. Chem. Biol. source

      Not checked in the free run.

    • cites [126] Philips, 2010, Stimulation of cell proliferation and expression of matrix metalloproteinase-1 and interluekin-8 genes in dermal fibroblasts by copper, Connect. Tissue Res. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A 25% zinc sulphate solution applied topically twice daily for 12 weeks was safe and effective for actinic keratoses, especially in patients with multiple actinic keratosis lesions.

    “actinic keratoses (a 25% zinc sulphate solution applied topically twice daily for 12 weeks was safe and effective, especially in patients with multiple actinic keratosis lesions) [113]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [113] Sharquie, 2012, Topical zinc sulphate (25%) solution: A new therapy for actinic keratosis, J. Cutan. Aesthet. Surg. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Copper stimulates the proliferation of dermal fibroblasts and is involved in the synthesis and stabilization of extracellular matrix skin proteins and angiogenesis.

    “Cu stimulates the proliferation of dermal fibroblasts and is involved in the synthesis and stabilization of extracellular matrix skin proteins and angiogenesis.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [118] Borkow, 2014, Using Copper to Improve the Well-Being of the Skin, Curr. Chem. Biol. source

      Not checked in the free run.

    • cites [126] Philips, 2010, Stimulation of cell proliferation and expression of matrix metalloproteinase-1 and interluekin-8 genes in dermal fibroblasts by copper, Connect. Tissue Res. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Zinc preparations in the form of pastes or ointments cleanse the skin of excess sebum, restore its natural pH, and have astringent, anti-inflammatory and anti-acne effects.

    “Zinc preparations in the form of pastes or ointments cleanse the skin of excess sebum, restore its natural pH, and have astringent, anti-inflammatory and anti-acne effects.”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [97] Devi, 2014, Zinc in human health, IOSR-JDMS source

      Not checked in the free run.

    • cites [98] Gupta, M., Mahajan, V.K., Mehta, K.S., and Chauhan, P.S. Zinc therapy in dermatology: A review. Dermatol. Res. Pract., 2014. source

      Not checked in the free run.

    • cites [99] Ogawa, Y., Kinoshita, M., Shimada, S., and Kawamura, T. (2018). Zinc and skin disorders. Nutrients, 10. source

      Not checked in the free run.

    • cites [107] Nitzan, 2006, Zinc in skin pathology and care, J. Dermatolog. Treat. source

      Not checked in the free run.

    • cites [110] Kim, 2014, Hair zinc levels and the efficacy of oral zinc supplementation in patients with atopic dermatitis, Acta Derm. Venereol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Copper deficiency reduces the activity of the enzyme Cu/Zn-SOD and ceruloplasmin, as well as copper-independent enzymes, including catalase and glutathione peroxidase.

    “Copper deficiency reduces the activity of the enzyme Cu/Zn-SOD and ceruloplasmin, as well as copper-independent enzymes, including catalase and glutathione peroxidase.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [127] Milewska, 2016, Trace elements as an activator of antioxidant enzymes, Postepy. Hig. Med. Dosw. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A 20% topical application of a zinc sulphate solution for 4 months to 2 years improved all types of skin lesions, softened the skin, lightened the skin color, and cleared the skin of solar keratosis and small malignancies in xeroderma pigmentosum.

    “xeroderma pigmentosum (a 20% topical application of a zinc sulphate solution for 4 months to 2 years improved all types of skin lesions, softened the skin, lightened the skin color, and cleared the skin of solar keratosis and small malignancies) [114]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [114] Sharquie, 2008, Topical therapy of xeroderma pigmentosa with 20% zinc sulfate solution, IASJ

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Zinc plays an important role in preventing damage induced by UV radiation and influences collagen metabolism.

    “It plays an important role in preventing the damage induced by UV radiation, influences collagen metabolism, exhibits antiandrogen properties by modulating the activity of type 1 and 2 5α-reductase, and also promotes lipogenesis and glucose transport through insulin-like effects on 3T3-L1 fibroblasts and adipocytes [98,107,108].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [98] Gupta, M., Mahajan, V.K., Mehta, K.S., and Chauhan, P.S. Zinc therapy in dermatology: A review. Dermatol. Res. Pract., 2014. source

      Not checked in the free run.

    • cites [107] Nitzan, 2006, Zinc in skin pathology and care, J. Dermatolog. Treat. source

      Not checked in the free run.

    • cites [108] Tang, 2001, Zinc has an insulin-like effect on glucose transport mediated by phosphoinositol-3-kinaseand Akt in 3T3-L1 fibroblasts and adipocytes, J. Nutr. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Zinc oxide, due to its ability to reflect and disperse UV rays, is used as a physical filter in sunscreens.

    “Zinc oxide, due to its ability to reflect and disperse UV rays, is used as a physical filter in sunscreens [97,98,99,107,110].”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [97] Devi, 2014, Zinc in human health, IOSR-JDMS source

      Not checked in the free run.

    • cites [98] Gupta, M., Mahajan, V.K., Mehta, K.S., and Chauhan, P.S. Zinc therapy in dermatology: A review. Dermatol. Res. Pract., 2014. source

      Not checked in the free run.

    • cites [99] Ogawa, Y., Kinoshita, M., Shimada, S., and Kawamura, T. (2018). Zinc and skin disorders. Nutrients, 10. source

      Not checked in the free run.

    • cites [107] Nitzan, 2006, Zinc in skin pathology and care, J. Dermatolog. Treat. source

      Not checked in the free run.

    • cites [110] Kim, 2014, Hair zinc levels and the efficacy of oral zinc supplementation in patients with atopic dermatitis, Acta Derm. Venereol. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Copper is a cofactor of tyrosinase, the main enzyme involved in synthesis of the skin pigment melanin.

    “Furthermore, Cu is a cofactor of tyrosinase, the main enzyme involved in synthesis of the skin pigment melanin [128].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [128] Olivares, 2009, New insights into the active site structure and catalytic mechanism of tyrosinase and its related proteins, Pigment Cell Melanoma Res. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Essential fatty acids have therapeutic properties (e.g., anti-inflammatory and anti-allergic) and exert protective effects.

    “EFAs have therapeutic properties (e.g., anti-inflammatory and anti-allergic) and exert protective effects.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [156] Michalak, 2018, Oils from fruit seeds and their dietetic and cosmetic significance, Herba Pol. source

      Not checked in the free run.

    • cites [157] Burris, 2013, Acne: The role of medical nutrition therapy, J. Acad. Nutr. Diet. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In comparison with other metal compounds, copper has a low allergenic potential, and the risk of adverse side effects due to skin contact with the metal is small.

    “In comparison with other metal compounds, copper has a low allergenic potential, and the risk of adverse side effects due to skin contact with the metal is small [132,133].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [132] Hostynek, 2003, Copper hypersensitivity: Dermatologic aspects-an overview, Rev. Environ. Health source

      Not checked in the free run.

    • cites [133] Fage, 2014, Copper hypersensitivity, Contact Dermat. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Silicone elastomeric particles can absorb various liquids, including emollients and sebum, and can thus be used as an agent to carry active ingredients to the skin or to control sebum deposition in the skin.

    “Silicone elastomeric particles can absorb various liquids, including emollients and sebum, and can thus be used as an agent to carry active ingredients to the skin or to control sebum deposition in the skin [136,142].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [136] Harlim, 2018, Silicon level in skin tissues of normal female individuals, J. Pakistan Assoc. Dermatologists.

      Not checked in the free run.

    • cites [142] Nair, 2013, Basic considerations in the dermatokinetics of topical formulations, Bras. J. Pharmaceut. Sci.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The symptoms of fatty acid deficiency include dryness of the epidermis, peeling, flabby skin, skin inflammation, an increased susceptibility to irritation and slower healing.

    “The symptoms of fatty acid deficiency include dryness of the epidermis, peeling, flabby skin, skin inflammation, an increased susceptibility to irritation and slower healing.”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [153] Correa, 2014, Molecular interactions of plant oil components with stratum corneum lipids correlate with clinical measures of skin barrier function, Exp. Dermatol. source

      Not checked in the free run.

    • cites [154] Feingold, 2014, Role of lipids in the formation and maintenance of the cutaneous permeability barier, Biochim. Biophys. Acta. source

      Not checked in the free run.

    • cites [158] Cakir, 2004, Essential oil and fatty acid composition of the fruits of Hippophae rhamnoides L. (Sea Buckthorn) and Myrtus communis L. from Turkey, Biochem. Syst. Ecol. source

      Not checked in the free run.

    • cites [159] Janssens, 2014, The important role of stratum corneum lipids for the cutaneous barrier function, Biochim. Biophys. Acta. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A deficiency of essential fatty acids can reduce the fluidity of sebum, which leads to the obstruction of the sebaceous glands and the appearance of blackheads and inflammation.

    “A deficiency of essential fatty acids can also reduce the fluidity of sebum, which leads to the obstruction of the sebaceous glands and the appearance of blackheads and inflammation [152,157].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [152] Michalak, 2018, Plant oils in cosmetology and dermatology, Pol. J. Cosmetol.

      Not checked in the free run.

    • cites [157] Burris, 2013, Acne: The role of medical nutrition therapy, J. Acad. Nutr. Diet. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Treatment with silicon may improve keratin structure in the hair and nails and reduce brittleness.

    “Treatment with silicon may also improve keratin structure in the hair and nails and reduce brittleness [138].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [138] Barel, 2005, Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin, Arch. Dermatol. Res. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    GLA applied topically as a cream penetrates to the stratum corneum, while taken orally, it reaches the dermis, enhancing its cohesiveness and preventing excessive TEWL.

    “GLA applied topically as a cream penetrates to the stratum corneum, while taken orally, it reaches the dermis, enhancing its cohesiveness and preventing excessive TEWL [156,157].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [156] Michalak, 2018, Oils from fruit seeds and their dietetic and cosmetic significance, Herba Pol. source

      Not checked in the free run.

    • cites [157] Burris, 2013, Acne: The role of medical nutrition therapy, J. Acad. Nutr. Diet. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Oral intake of maltodextrin-stabilized orthosilicic acid and monomethylsilanetriol improves skin parameters, increases eyelash length, reduces facial wrinkles and UV spots, and acts as aluminum detoxification agents.

    “Ferreira et al. investigated the oral intake of two forms of Si—maltodextrin-stabilized orthosilicic acid (M-OSA) and monomethylsilanetriol (MMST)—and their effects on the nails, skin and hair. They were found to improve skin parameters, increase eyelash length, reduce facial wrinkles and UV spots, and act as aluminum detoxification agents [135].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [135] Ferreira, A.O., Freire, É.S., Polonini, H.C., da Silva, P.J.L.C., Brandão, M.A.F., and Raposo, N.R.B. (2018). Anti-aging effects of monomethylsilanetriol and maltodextrin-stabilized orthosilicic acid on nails, skin and hair. Cosmetics, 5. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The copper tripeptide complex (GHK-Cu and GSH-Cu) plays an important role in the protection and regeneration of skin tissue, increases the synthesis of collagen and elastin, and improves the condition of ageing skin.

    “The copper tripeptide complex (GHK-Cu and GSH-Cu) plays an important role in the protection and regeneration of skin tissue, increases the synthesis of collagen and elastin, and improves the condition of ageing skin.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [130] Pickart, L., and Margolina, A. (2018). Skin regenerative and anti-cancer actions of copper peptides. Cosmetics, 5. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Owing to unsaturated fatty acids, which, alongside ceramides and cholesterol, are components of the intracellular cement, the skin can act as an effective barrier limiting TEWL, thus ensuring adequate hydration and protecting against external factors.

    “Owing to unsaturated fatty acids, which, alongside ceramides and cholesterol, are components of the intracellular cement, the skin can act as an effective barrier limiting TEWL, thus ensuring adequate hydration and protecting against external factors [153,154,156].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [153] Correa, 2014, Molecular interactions of plant oil components with stratum corneum lipids correlate with clinical measures of skin barrier function, Exp. Dermatol. source

      Not checked in the free run.

    • cites [154] Feingold, 2014, Role of lipids in the formation and maintenance of the cutaneous permeability barier, Biochim. Biophys. Acta. source

      Not checked in the free run.

    • cites [156] Michalak, 2018, Oils from fruit seeds and their dietetic and cosmetic significance, Herba Pol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Silicon promotes the synthesis of elastin and GAGs, helps to preserve blood vessel elasticity, and increases the resistance and thickness of nail and hair fibers.

    “Si also promotes the synthesis of elastin and GAGs, helps to preserve blood vessel elasticity, and increases the resistance and thickness of nail and hair fibers [135].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [135] Ferreira, A.O., Freire, É.S., Polonini, H.C., da Silva, P.J.L.C., Brandão, M.A.F., and Raposo, N.R.B. (2018). Anti-aging effects of monomethylsilanetriol and maltodextrin-stabilized orthosilicic acid on nails, skin and hair. Cosmetics, 5. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In a group of 50 women with photodamaged facial skin taking 10 mg of silicon/day orally for 20 weeks, significant improvements were observed in the surface characteristics and mechanical properties of the skin, as was a positive effect on the brittleness of the hair and nails.

    “In a group of 50 women with photodamaged facial skin taking 10 mg of Si/day orally for 20 weeks, significant improvements were observed in the surface characteristics and mechanical properties of the skin, as was a positive effect on the brittleness of the hair and nails [138].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [138] Barel, 2005, Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin, Arch. Dermatol. Res. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Silicones are included in cosmetic formulations such as hair conditioners and shampoos, as well as in facial creams to protect and improve the skin's strength and elasticity.

    “Silicones are included in cosmetic formulations such as hair conditioners and shampoos to give hair a silky appearance and shine, as well as in facial creams to protect and improve the skin’s strength and elasticity [134,136].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [134] Addor, 2016, Use of silicon for skin and hair care: An approach of chemical forms available and efficacy, An. Bras. Dermatol. source

      Not checked in the free run.

    • cites [136] Harlim, 2018, Silicon level in skin tissues of normal female individuals, J. Pakistan Assoc. Dermatologists.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Organic silicon plays an important role in skin structure, promotes neocollagenesis, strengthens connective tissue, and reduces the risk of alopecia.

    “Organic silicon plays an important role in skin structure, promotes neocollagenesis, strengthens connective tissue, and reduces the risk of alopecia [139].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [139] Mancinella, 1991, Silicon, a trace element essential for living organisms. Recent knowledge on its preventive role in atherosclerotic process, aging and neoplasms, Clin. Ter.

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Supplementation of diets with vegetable or fish oils may generate local cutaneous anti-inflammatory metabolites, which could serve as adjuncts in the management of skin inflammatory disorders.

    “Furthermore, the supplementation of diets with vegetable or fish oils may generate local cutaneous anti-inflammatory metabolites, which could serve as adjuncts in the management of skin inflammatory disorders [185].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [185] Ziboh, 1996, The significance of polyunsaturated fatty acids in cutaneous biology, Lipids source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A 10-week administration of an antioxidant mixture of pycnogenol, evening primrose oil, vitamin C and vitamin E to hairless mice irradiated three times a week with UVB radiation significantly prevented the UVB-induced expression of MMPs and mitogen-activated protein kinase, as well as the activation of the transcription factor AP-1.

    “The study showed that a 10-week administration of the antioxidants to hairless mice irradiated three times a week with UVB radiation significantly prevented the UVB-induced expression of MMPs and mitogen-activated protein (MAP) kinase, as well as the activation of the transcription factor AP-1.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [203] Cho, 2007, Anti-wrinkling effects of the mixture of vitamin C, vitamin E, pycnogenol and evening primrose oil, and molecular mechanisms on hairless mouse skin caused by chronic ultraviolet B irradiation, Photodermatol. Photoimmunol. Photomed source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Polyphenols exhibit anti-inflammatory, antibacterial, antifungal, antiviral, antiallergic, anticancer and anticoagulant properties.

    “They exhibit anti-inflammatory, antibacterial, antifungal, antiviral, antiallergic, anticancer and anticoagulant properties [190,191,192,193,197].”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [190] Han, 2007, Dietary polyphenols and their biological significance, Int. J. Mol. Sci. source

      Not checked in the free run.

    • cites [191] Tsao, 2010, Chemistry and biochemistry of dietary polyphenols, Nutrients source

      Not checked in the free run.

    • cites [192] Shahidi, 2015, Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects –A review, J. Funct. Foods source

      Not checked in the free run.

    • cites [193] Jain, 2010, Flavonoids as nutraceuticals. A review, Herba Pol.

      Not checked in the free run.

    • cites [197] Nichols, 2010, Skin photoprotection by natural polyphenols: Anti-inflammatory, antioxidant and DNA repair mechanisms, Arch. Dermatol. Res. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Fish oils have a protective role and can reduce the severity of erythema.

    “There are studies indicating that fish oils have a protective role and can reduce the severity of erythema.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [186] Rhodes, 1994, Dietary fish-oil supplementation in humans reduces UVB-erythemal sensitivity but increases epidermal lipid peroxidation, J. Investig. Derm. source

      Not checked in the free run.

    • cites [187] Rhodes, 2003, Effect of eicosapentaenoic acid, an omega-3 polyunsaturated fatty acid, on UVR-related cancer risk in humans. An assessment of early genotoxic markers, Carcinogenesis source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Pomegranate extract has photochemoprotective, antioxidant, anti-inflammatory and antiproliferative properties.

    “Research has confirmed the photochemoprotective, antioxidant, anti-inflammatory and antiproliferative properties of pomegranate extract.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [208] Afaq, 2005, Anthocyanin- and hydrolyzable tannin-rich pomegranate fruit extract modulates MAPK and NF-kappa B pathways and inhibits skin tumorigenesis in CD-1 mice, Int. J. Cancer source

      Not checked in the free run.

    • cites [209] Khan, 2012, Pomegranate fruit extract inhibits UVB-induced inflammation and proliferation by modulating NF-κB and MAPK signaling pathways in mouse skin, Photochem. Photobiol. source

      Not checked in the free run.

    • cites [210] Kasai, 2006, Effects of oral administration of ellagic acid-rich pomegranate extract on ultraviolet-induced pigmentation in the human skin, J. Nutr. Sci. Vitaminol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Polyphenols soothe irritation and reduce the redness of skin, accelerate the natural regeneration of the epidermis, stabilize the capillaries, improve microcirculation and elasticity in the skin, and protect against harmful external factors, including UV radiation.

    “Furthermore, they soothe irritation and reduce the redness of skin, accelerating the natural regeneration of the epidermis, stabilizing the capillaries, improving microcirculation and elasticity in the skin, and protecting against harmful external factors, including UV radiation [188,197,198,200].”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [188] Michalak, 2017, Sources of vegetable dyes and their use in cosmetology, Pol. J. Cosmetol.

      Not checked in the free run.

    • cites [197] Nichols, 2010, Skin photoprotection by natural polyphenols: Anti-inflammatory, antioxidant and DNA repair mechanisms, Arch. Dermatol. Res. source

      Not checked in the free run.

    • cites [198] Zillich, 2015, Polyphenols as active ingredients for cosmetic products, Int. J. Cosmet. Sci. source

      Not checked in the free run.

    • cites [200] Chen, 2012, The role of antioxidants in photoprotection: A critical review, J. Am. Acad. Dermatol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In a randomized double-blind trial in 42 healthy patients taking 4 g/day of EPA or monounsaturated oleic acid for three months, an increase in the UV-induced erythematous threshold was observed, as was a decrease in the expression of the protein p53, a marker of DNA damage induced by UV radiation.

    “In a randomized double-blind trial in 42 healthy patients taking 4 g/day of EPA or monounsaturated oleic acid for three months, an increase in the UV-induced erythematous threshold was observed, as was a decrease in the expression of the protein p53, a marker of DNA damage induced by UV radiation.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [187] Rhodes, 2003, Effect of eicosapentaenoic acid, an omega-3 polyunsaturated fatty acid, on UVR-related cancer risk in humans. An assessment of early genotoxic markers, Carcinogenesis source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Pomegranate fruit extract has been shown to reduce UVB-induced oxidative stress and the oxidation of skin proteins.

    “Pomegranate fruit extract has been shown to reduce UVB-induced oxidative stress and the oxidation of skin proteins [209]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [209] Khan, 2012, Pomegranate fruit extract inhibits UVB-induced inflammation and proliferation by modulating NF-κB and MAPK signaling pathways in mouse skin, Photochem. Photobiol. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Oils rich in essential fatty acids improve skin hydration, have a regenerative effect on the damaged epidermal lipid barrier, and regulate skin metabolism.

    “Oils rich in EFAs improve skin hydration, have a regenerative effect on the damaged epidermal lipid barrier, and regulate skin metabolism.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [152] Michalak, 2018, Plant oils in cosmetology and dermatology, Pol. J. Cosmetol.

      Not checked in the free run.

    • cites [157] Burris, 2013, Acne: The role of medical nutrition therapy, J. Acad. Nutr. Diet. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    EPAs have a UV-filtering effect and longer-term supplementation may reduce the risk of skin cancer in humans.

    “The results indicate that EPAs have a UV-filtering effect and suggest that longer-term supplementation may reduce the risk of skin cancer in humans [187].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [187] Rhodes, 2003, Effect of eicosapentaenoic acid, an omega-3 polyunsaturated fatty acid, on UVR-related cancer risk in humans. An assessment of early genotoxic markers, Carcinogenesis source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Polyphenols can chelate transition metal cations (e.g., Cu2+ and Fe2+), thus preventing Haber-Weiss and Fenton reactions and inhibiting the activity of many enzymes involved in free radical generation.

    “Polyphenols can also chelate transition metal cations (e.g., Cu2+ and Fe2+), thus preventing Haber–Weiss and Fenton reactions (which lead to the generation of the extremely reactive hydroxyl radical •OH) and also inhibiting the activity of many enzymes involved in free radical generation (e.g., xanthine oxidase, protein kinase and lipoxygenase).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [194] Miller, 1996, Structure-antioxidant activity relationships of flavonoids and phenolic acids, Free Radic. Biol. Med. source

      Not checked in the free run.

    • cites [195] Bravo, 1998, Polyphenols: Chemistry, dietary sources, metabolism, and nutritional significance, Nutr. Rev. source

      Not checked in the free run.

    • cites [202] Gupta, 2010, Recent updates on free radicals scavenging flavonoids: An overview, Asian. J. Plant Sci. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Plant polyphenols are considered important substances for skin function, with hydrating, smoothing, softening, soothing and astringent effects.

    “Plant polyphenols are considered important substances for skin function, with hydrating, smoothing, softening, soothing and astringent effects [25,190,193,197,198,199].”
    Quote in the paperNot a substantial claim0 of 6 sources checked
    • cites [25] Anunciato, 2012, Carotenoids and polyphenols in nutricosmetics, nutraceuticals, and cosmeceuticals, J. Cosmet. Dermatol. source

      Not checked in the free run.

    • cites [190] Han, 2007, Dietary polyphenols and their biological significance, Int. J. Mol. Sci. source

      Not checked in the free run.

    • cites [193] Jain, 2010, Flavonoids as nutraceuticals. A review, Herba Pol.

      Not checked in the free run.

    • cites [197] Nichols, 2010, Skin photoprotection by natural polyphenols: Anti-inflammatory, antioxidant and DNA repair mechanisms, Arch. Dermatol. Res. source

      Not checked in the free run.

    • cites [198] Zillich, 2015, Polyphenols as active ingredients for cosmetic products, Int. J. Cosmet. Sci. source

      Not checked in the free run.

    • cites [199] Chuarienthong, 2010, Clinical efficacy comparison of anti-wrinkle cosmetics containing herbal flavonoids, Int. J. Cosmet. Sci. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The oral administration of the antioxidant mixture can inhibit wrinkle formation by preventing the expression of MMPs and increasing collagen synthesis.

    “The results indicate that the oral administration of the antioxidant mixture can inhibit wrinkle formation by preventing the expression of MMPs and increasing collagen synthesis [203].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [203] Cho, 2007, Anti-wrinkling effects of the mixture of vitamin C, vitamin E, pycnogenol and evening primrose oil, and molecular mechanisms on hairless mouse skin caused by chronic ultraviolet B irradiation, Photodermatol. Photoimmunol. Photomed source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Polyphenols used topically and orally may be effective in treating certain dermatological conditions, including anogenital warts, alopecia, acne vulgaris, fungal infections, hyperpigmentation and photoaged skin.

    “Polyphenols used topically and orally may be effective in treating certain dermatological conditions, including anogenital warts, alopecia, acne vulgaris, fungal infections, hyperpigmentation and photoaged skin [217].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [217] Tuong, 2015, Polyphenols as novel treatment options for dermatological diseases: A systematic review of clinical trials, J. Dermatolog. Treat. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The content of carotenoids in human skin varies, with the highest levels observed in parts of the body with high concentrations of sweat and sebaceous glands (e.g., the forehead and hands).

    “The content of carotenoids in human skin varies, with the highest levels observed in parts of the body with high concentrations of sweat and sebaceous glands (e.g., the forehead and hands).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [220] Balić, A., and Mokos, M. (2019). Do we utilize our knowledge of the skin protective effects of carotenoids enough?. Antioxidants, 8. source

      Not checked in the free run.

    • cites [229] Darvin, 2011, The role of carotenoids in human skin, Molecules source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In a double-blind placebo trial in 40 women, a 10-percent green tea cream applied together with 300 mg twice-daily green tea oral supplementation showed significant improvements in elastic tissue content, but no significant clinical changes.

    “Histological examination showed significant improvements in elastic tissue content, but no significant changes were demonstrated clinically.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [214] Chiu, 2005, Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin, Dermatol. Surg. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Bakuchiol can prevent wrinkles; improve pigmentation, elasticity and firmness; and reduce overall photodamage.

    “Chaudhuri and Bojanowski showed that bakuchiol can prevent wrinkles; improve pigmentation, elasticity and firmness; and reduce overall photodamage.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] Chaudhuri, 2014, Bakuchiol: A retinol-like functional compound revealed by gene expression profiling and clinically proven to have anti-aging effects, Int. J. Cosmet. Sci. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Pomegranate fruit extract improves the color of the skin and restores the glow of skin exposed to UV radiation.

    “and also to improve the color of the skin and restore the glow of skin exposed to UV radiation [210].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [210] Kasai, 2006, Effects of oral administration of ellagic acid-rich pomegranate extract on ultraviolet-induced pigmentation in the human skin, J. Nutr. Sci. Vitaminol. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Carotenoids are present in the horny layer of the epidermis, as confirmed by Raman spectroscopy.

    “They are also present in the horny layer of the epidermis, as confirmed by Raman spectroscopy.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [220] Balić, A., and Mokos, M. (2019). Do we utilize our knowledge of the skin protective effects of carotenoids enough?. Antioxidants, 8. source

      Not checked in the free run.

    • cites [229] Darvin, 2011, The role of carotenoids in human skin, Molecules source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In the human body, carotenoids mainly accumulate in lipid tissue cells and the liver.

    “In the human body, carotenoids mainly accumulate in lipid tissue cells and the liver.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [220] Balić, A., and Mokos, M. (2019). Do we utilize our knowledge of the skin protective effects of carotenoids enough?. Antioxidants, 8. source

      Not checked in the free run.

    • cites [229] Darvin, 2011, The role of carotenoids in human skin, Molecules source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Interpretationcitation

    A clinically perceptible improvement might require a longer period of green tea polyphenol administration.

    “The authors concluded that a clinically perceptible improvement might require a longer period of GTP administration.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [214] Chiu, 2005, Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin, Dermatol. Surg. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Green tea polyphenols exhibit anti-inflammatory and antioxidant properties and the ability to scavenge free radicals.

    “GTPs also exhibit anti-inflammatory and antioxidant properties and the ability to scavenge free radicals [214].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [214] Chiu, 2005, Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin, Dermatol. Surg. source

      Not checked in the free run.

  • The quote only partly states this claim.

    Premisecitation

    In the Yoon et al. study, astaxanthin (2 mg/day) combined with collagen hydrolysate (3 g/day) supplementation increased the expression of procollagen type I mRNA in moderately photoaged human skin.

    “Yoon et al. investigated the effect of astaxanthin (2 mg/day) and collagen hydrolysate (3 g/day) supplementation on moderately photoaged skin in humans.”
    • Also stated in: § 2.5. Carotenoids · plain
      “The bioactives significantly improved barrier integrity, reduced TEWL, and increased the expression of procollagen type I mRNA.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [234] Juturu, 2016, Overall skin tone and skin-lightening-improving effects with oral supplementation of lutein and zeaxanthin isomers: A double-blind, placebo-controlled clinical trial, Clin. Cosmet. Investig. Dermatol. source

      Not checked in the free run.

  • The quote only partly states this claim.

    Premisecitation

    In the Yoon et al. study, astaxanthin (2 mg/day) combined with collagen hydrolysate (3 g/day) supplementation reduced TEWL in moderately photoaged human skin.

    “Yoon et al. investigated the effect of astaxanthin (2 mg/day) and collagen hydrolysate (3 g/day) supplementation on moderately photoaged skin in humans.”
    • Also stated in: § 2.5. Carotenoids · plain
      “The bioactives significantly improved barrier integrity, reduced TEWL, and increased the expression of procollagen type I mRNA.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [234] Juturu, 2016, Overall skin tone and skin-lightening-improving effects with oral supplementation of lutein and zeaxanthin isomers: A double-blind, placebo-controlled clinical trial, Clin. Cosmet. Investig. Dermatol. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    A photoprotective effect and reduction in the severity of UV-induced erythema can be ascribed to the entire family of carotenoids.

    “These studies indicate that a photoprotective effect and reduction in the severity of UV-induced erythema can be ascribed to the entire family of carotenoids.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationnone given

    Substances that protect and restore the epidermal barrier, such as omega-3 and omega-6 fatty acids, reduce TEWL, ensure an appropriate level of skin hydration, and protect against external factors and inflammation-induced damage.

    “It is worth noting the substances that protect and restore the epidermal barrier, which reduces TEWL, ensuring an appropriate level of skin hydration and protecting against external factors and the damage induced by inflammation (e.g., omega-3 and omega-6 fatty acids).”
    Quote in the paperNot a substantial claim
96 of 96

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Juturu study is assigned the Yoon reference

    Minor

    The text cites reference [233] for a study by Juturu et al., but reference [233] is a study by Yoon et al. The Juturu study appears as reference [234].

  • Yoon study is assigned the Juturu reference

    Minor

    The text cites reference [234] for a study by Yoon et al., but reference [234] is a study by Juturu et al. The Yoon study appears as reference [233].

  • The review says unsaturated fatty acids are both synthesized and not synthesized in the body

    Minor

    The review states that unsaturated fatty acids are not synthesized in the human body, but elsewhere says that the unsaturated fatty acid GLA is formed from LA by an enzymatic reaction.

3 of 3

Cites

Flagged first, then by citations

Research works printed but not linked: 7

  1. Janda, 2015, Vitamin C – structure, properties, occurrence and functions, Pom. J. Life Sci., 61, 419
  2. Zervoudis, 2010, Complementary treatment with oralpidotimod plus vitamin C after laser vaporization for female genital warts: Aprospective study, J. Med. Life, 3, 286
  3. Dahiaya, 2006, Cosmeceuticals: A review of their use for aging and photoaged skin, Cosmet. Dermatol., 19, 479
  4. Michalak, 2018, Plant oils in cosmetology and dermatology, Pol. J. Cosmetol., 21, 2
  5. Michalak, 2017, Sources of vegetable dyes and their use in cosmetology, Pol. J. Cosmetol., 20, 196
  6. Eldahshan, 2013, Carotenoids, J. Pharmacogn. Phytochem., 2, 225
  7. Yamashita, 2002, Cosmetic benefit of dietary supplements including astaxanthin and tocotrienol on human skin, Food Style, 216, 112

Cited by

Sorted by citations

Related

Authors
Michalak, M., Pierzak, M., Kręcisz, B., & Suliga, E.
Affiliations
Jan Kochanowski University (PL)
Corresponding author
Michalak, Monika
ORCID
Venue
Nutrients
Publisher
MDPI AG
Published
2021-01-12
Volume
13
Issue
1
Pages
203
ISSN
2072-6643 (ISSN-L)
DOI
10.3390/nu13010203
PMC
PMC7827176
OpenAlex
W3118502052
Semantic Scholar
188c774000fdae94a0c23e9503dd50a233b3c1c6
Cited by
345
References
238
Citations by year
2026: 42 · 2025: 75 · 2024: 106 · 2023: 71 · 2022: 31 · 2021: 20
FWCI
10.08
Type
journal article
Language
en
Open access
Licence
Locations
  • Nutrients (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, other-oa)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
Regional Initiative of Excellence in 2019–2022 (024/RID/2018/19)
Topics
  • Health Sciences › Medicine › Dermatology › Skin Protection and Aging
  • Health Sciences › Medicine › Biochemistry › Phytochemicals and Antioxidant Activities
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › melanin and skin pigmentation
Keywords
bioactive compounds, skin health, vitamins, minerals, fatty acids, polyphenols, carotenoids, skin aging, skin elasticity, skin firmness, wrinkles, skin hydration, skin color
MeSH terms
Antioxidants, Carotenoids, Humans, Minerals, Skin, Vitamins, Skin Aging

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

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