Cited by 685Organic Food and AgriculturePhytochemicals and Antioxidant ActivitiesFood and Agricultural Sciences

Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses

Open access
Barański, Marcin, Średnicka-Tober, Dominika, Volakakis, Nikolaos, Seal, Chris, Sanderson, Roy, Stewart, Gavin B., Benbrook, Charles, Biavati, Bruno +10 more·2014·British Journal of Nutrition

Abstract

Demand for organic foods is partially driven by consumers' perceptions that they are more nutritious. However, scientific opinion is divided on whether there are significant nutritional differences between organic and non-organic foods, and two recent reviews have concluded that there are no differences. In the present study, we carried out meta-analyses based on 343 peer-reviewed publications that indicate statistically significant and meaningful differences in composition between organic and non-organic crops/crop-based foods. Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI 5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17, 86) % higher, respectively. Many of these compounds have previously been linked to a reduced risk of chronic diseases, including CVD and neurodegenerative diseases and certain cancers, in dietary intervention and epidemiological studies. Additionally, the frequency of occurrence of pesticide residues was found to be four times higher in conventional crops, which also contained significantly higher concentrations of the toxic metal Cd. Significant differences were also detected for some other (e.g. minerals and vitamins) compounds. There is evidence that higher antioxidant concentrations and lower Cd concentrations are linked to specific agronomic practices (e.g. non-use of mineral N and P fertilisers, respectively) prescribed in organic farming systems. In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production seasons.

AI snapshot

Written from the paper’s full text.

TL;DR

This systematic review and meta-analysis of 343 peer-reviewed publications reports that organic crops/crop-based foods have higher antioxidant activity and higher concentrations of several antioxidants/(poly)phenolics, lower Cd concentrations, and a lower frequency of detectable pesticide residues than conventional comparators. The authors conclude these differences are statistically significant and potentially nutritionally meaningful, while noting high heterogeneity and uncertainty about human health impacts.

Key findings

  • Organic crops had substantially higher concentrations of several antioxidants/(poly)phenolics: phenolic acids 19 % (95 % CI 5, 33) %, flavanones 69 % (95 % CI 13, 125) %, stilbenes 28 % (95 % CI 12, 44) %, flavones 26 % (95 % CI 3, 48) %, flavonols 50 % (95 % CI 28, 72) %, and anthocyanins 51 % (95 % CI 17, 86) % higher; antioxidant activity was 17 % (95 % CI 3, 32) % higher in organic crops.
  • The frequency of detectable pesticide residues was four times higher in conventional crops: 46 % (95 % CI 38, 55) % of conventional samples vs 11 % (95 % CI 7, 14) % of organic samples.
  • Organic crops had lower Cd concentrations, with a mean percentage difference of −48 % (95 % CI −112, 16) %, and lower total N (−10 %, 95 % CI −15, −4), proteins (−15 %, 95 % CI −27, −3), amino acids (−11 %, 95 % CI −14, −8), and fibre (−8 %, 95 % CI −14, −2); they had higher total carbohydrates (25 %, 95 % CI 5, 45) and reducing sugars (7 %, 95 % CI 4, 11).
  • No significant differences were detected for As and Pb; for minerals, organic crops had lower Cr (−59 %, 95 % CI −147, 30) and Sr (−26 %, 95 % CI −45, −6) but higher Mo (65 %, 95 % CI 26, 105) and Rb (82 %, 95 % CI 6, 157). GRADE assessment indicated moderate or high reliability for most antioxidant/(poly)phenolic parameters with significant differences and moderate reliability for Cd.

Methods

  • Systematic literature review and meta-analyses based on 343 peer-reviewed publications; 156 publications met criteria for the standard weighted meta-analysis and 343 for the standard unweighted meta-analysis. Searches used Web of Knowledge for January 1992–December 2011, plus 208 additional publications, yielding 17 333 references; 448 suitable publications were identified and 105 rejected.
  • Data came from matched farm comparisons (116 papers), basket/retail surveys (55 papers), controlled field experiments (154 papers), or more than one study type (18 papers). Weighted random-effects meta-analyses used standardised mean differences; unweighted meta-analyses used ln-transformed organic:conventional mean ratios; pesticide residue frequency was analysed with ln OR; sensitivity analyses and an adapted GRADE assessment were performed.
  • Analyses covered 182 composition parameters from 907 reported parameters, including antioxidants/(poly)phenolics, vitamins, macronutrients, minerals, toxic metals, nitrate/nitrite, and pesticide residues.

Limitations

  • The paper states that heterogeneity was extremely high (I² > 75 %) for most composition parameters, publication bias was strongly suspected for approximately half of parameters, and many studies lacked standardised measurements, measures of variance/replication, or certified reference materials.
  • The paper states that pesticide residue comparisons were limited: only eleven studies compared frequencies, eight focused on one crop species, no comparative studies for cereals, oilseeds and pulses were identified, and available data did not allow robust comparisons of pesticide concentrations.
  • The paper states that human health impacts remain uncertain: there is a lack of knowledge about uptake, bioavailability and mechanisms of (poly)phenolics, only two human dietary intervention studies used conventional vs organic diets and were inconclusive, and potential health benefits of lower Cd or pesticide exposure are difficult to estimate. Evident from the text: the meta-analysis synthesises observational and field studies and cannot establish causality, and high variation by crop type, country, and agronomic/pedo-climatic background limits generalisability.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1017/s0007114514001366

Cites

67 of 67 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 114 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Anthocyanin concentrations are an estimated 51% higher in organic crops/crop-based foods (95% CI 17, 86).

    “Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI 5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17,”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • Findingown data

    Flavanone concentrations are an estimated 69% higher in organic crops/crop-based foods (95% CI 13, 125).

    “Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI 5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17,”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • Findingown data

    Conventional crops contain significantly higher concentrations of the toxic metal Cd than organic crops.

    “which also contained significantly higher concentrations of the toxic metal Cd”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • Findingown data

    Phenolic acid concentrations are an estimated 19% higher in organic crops/crop-based foods (95% CI 5, 33).

    “Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI 5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17,”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • Findingown data

    Flavonol concentrations are an estimated 50% higher in organic crops/crop-based foods (95% CI 28, 72).

    “Most importantly, the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI 5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17,”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • May combine two claims. 48
  • Classified as probably not a substantial claim. 32
  • May combine two claims.

    Findingown data

    Both weighted and unweighted meta-analyses detected significantly higher antioxidant activity in organic crops, with a mean percentage difference of 17% (95% CI 3, 32).

    “Both weighted and unweighted meta-analyses detected a significantly higher antioxidant activity in organic crops (Fig. 3) and the MPD was 17 (95 % CI 3, 32) % (Fig. 3).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • May combine two claims.

    Findingown data

    Weighted meta-analysis detected lower Mn and higher Ga and Mg in organic crops; unweighted meta-analysis detected slightly higher Zn in organic crops.

    “Also, lower concentrations of Mn ( − 8 (95 % CI − 13, − 3) %) and higher concentrations of Ga and Mg in organic crops (57 (95 % CI − 122, 8) % and 4 (95 % CI − 5, 13) %, respectively) were detected only by the weighted meta-analysis, while slightly higher concentrations of Zn (5 (95 % CI − 6, 15) %) in organic crops were only detected by the unweighted meta-analysis (see online supplementary Table”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    MPD were 17% (95% CI 0, 34) for total carotenoids, 15% (95% CI -3, 32) for carotenoids, 12% (95% CI -4, 28) for xanthophylls, 5% (95% CI -3, 13) for lutein, 6% (95% CI -3, 15) for vitamin C, and -15% (95% CI -49, 19) for vitamin E.

    “The MPD were 17 (95 % CI 0, 34) % for total carotenoids, 15 (95 % CI − 3, 32) % for carotenoids (where data reported for all individual carotenoid compounds were included in the same analysis), 12 (95 % CI − 4, 28) % for xanthophylls, 5 (95 % CI − 3, 13) % for lutein, 6 (95 % CI − 3, 15) % for vitamin C and − 15 (95 % CI − 49, 19) % for vitamin E.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    When total carotenoids and xanthophylls were analysed separately by crop type, significantly higher concentrations in organic samples were detected only for fruits, with interactions for carotenoids but not xanthophylls.

    “When data reported for total carotenoids and xanthophylls in fruits, vegetables, cereals and processed crop-based compound foods were analysed separately, significantly higher concentrations in organic samples were detected only for fruits (Fig. 4), with evidence of interactions being detected for carotenoids, but not for xanthophylls.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    For the ferric reducing antioxidant power and oxygen radical absorbance capacity assays, similar results were obtained with only the standard unweighted meta-analysis.

    “for the ferric reducing antioxidant power and oxygen radical absorbance capacity assays with only the standard unweighted meta-analysis”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • May combine two claims.

    Findingown data

    Unweighted meta-analysis detected higher concentrations of total carotenoids, carotenoids, and lutein in organic crops.

    “Higher concentrations of total carotenoids, carotenoids (where data reported for all individual phenolic acid compounds were included in the same analysis) and lutein were also detected by the unweighted meta-analysis (Fig. 3).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Both weighted and unweighted meta-analyses detected significantly lower concentrations of Cr and Sr and significantly higher concentrations of Mo and Rb in organic crops.

    “However, for a small number of minerals, differences in composition were identified by both weighted and unweighted meta-analyses, which detected significantly lower concentrations of Cr and Sr ( − 59 (95 % CI − 147, 30) % and − 26 (95 % CI − 45, − 6) %, respectively), but significantly higher concentrations of Mo and Rb (65 (95 % CI 26, 105) % and 82 (95 % CI 6, 157) %, respectively) in organic”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    MPD were -48% (95% CI -112, 16) for Cd and -10% (95% CI -15, -4) for N.

    “The MPD were − 48 (95 % CI − 112, 16) % for Cd, − 10 (95 % CI − 15, − 4) % for N, − 30 (95 % CI − 144, 84) % for and − 87 (95 % CI − 225, 52) % for (Fig. 3).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    When analysed separately by crop type, significant differences for phenolic compounds and phenolic acids were detected only in fruits, and a trend for flavanones in fruits, with no evidence of interaction.

    “When data reported for phenolic compounds, phenolic acids and flavanones in fruits, vegetables, cereals and/or processed crop-based foods were analysed separately, significant differences were detected only for the concentrations of phenolic compounds and phenolic acids in fruits and a trend towards a significant difference (P= 0·09) was detected for the concentrations of flavanones in fruits (Fig”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    When flavones and flavonols were analysed separately by crop type, significant differences were detected for vegetables and cereals but not fruits, with evidence of interactions.

    “In contrast, when differences in the concentrations of flavones and flavonols were analysed separately for fruits, vegetables and cereals, significant differences were detected for vegetables and cereals, but not for fruits, with evidence of interactions (Fig. 4).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Inclusion of data without variance measures yielded similar MPD for phenolic compounds, phenolic acids, chlorogenic acid, flavones, quercetin, kaempferol and anthocyanins; higher for phenolic acids (total), stilbenes and quercetin-3-rutinoside; and lower for flavonoids, flavanones and flavonols.

    “Inclusion of data for which no measures of variance were reported in the calculation of MPD yielded similar values for phenolic compounds, phenolic acids, chlorogenic acid, flavones, quercetin, kaempferol and anthocyanins; higher values for phenolic acids (total), stilbenes and quercetin-3-rutinoside; and lower values for flavonoids, flavanones and flavonols (see Fig. 4 and online supplementary”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    MPD were 25% (95% CI 5, 45) for total carbohydrates, 11% (95% CI 2, 20) for carbohydrates, 7% (95% CI 4, 11) for reducing sugars, -15% (95% CI -27, -3) for proteins, -11% (95% CI -14, -8) for amino acids, 2% (95% CI -1, 6) for DM, and -8% (95% CI -14, -2) for fibre.

    “The MPD were 25 (95 % CI 5, 45) % for total carbohydrates, 11 (95 % CI 2, 20) % for carbohydrates (where data reported for all individual phenolic acid compounds were included in the same analysis), 7 (95 % CI 4, 11) % for reducing sugars, − 15 (95 % CI − 27, − 3) % for proteins, − 11 (95 % CI − 14, − 8) % for amino acids, 2 (95 % CI − 1, 6) % for DM and − 8 (95 % CI − 14, − 2) % for fibre.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Both unweighted and weighted meta-analyses detected significantly higher concentrations of xanthophylls and l-ascorbic acid and significantly lower concentrations of vitamin E in organic crops.

    “Both unweighted and weighted meta-analyses detected significantly higher concentrations of xanthophylls and l-ascorbic acid and significantly lower concentrations of vitamin E in organic crops.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Both weighted and unweighted meta-analyses detected significantly lower concentrations of Cd and total N in organic crops.

    “Both weighted and unweighted meta-analyses detected significantly lower concentrations of the toxic metal Cd and total N in organic crops, while lower concentrations of and in organic crops were detected only by the unweighted meta-analysis (Fig. 3).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    When proteins and amino acids were analysed separately by crop type, significant differences were detected for cereals and processed crop-based foods but not vegetables, with no evidence of interaction.

    “When data reported for proteins and amino acids in vegetables, cereals and/or processed crop-based foods were analysed separately, significant differences were detected for cereals and processed crop-based foods, but not for vegetables (Fig. 4), although there was no evidence of an interaction.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Conventional fruits had higher frequency of pesticide residues (75%, 95% CI 65, 85) than vegetables (32%, 95% CI 22, 43) and crop-based compound foods (45%, 95% CI 25, 65), while contamination rates were very similar in different organic crop types, resulting in significant differences in OR for different crop types.

    “Conventional fruits had a higher frequency (75 (95 % CI 65, 85) %) of occurrence of pesticide residues than vegetables (32 (95 % CI 22, 43) %) and crop-based compound foods (45 (95 % CI 25, 65) %), while contamination rates were very similar in the different organic crop types. This resulted in significant differences in the OR for different crop types (Fig. 5).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    When N and Cd concentrations were analysed separately by crop type, significant differences were detected for cereals but not vegetables and/or fruits, with no evidence of interaction.

    “When data reported for N and Cd concentrations in fruits, vegetables and cereals were analysed separately, significant differences were detected for cereals, but not for vegetables and/or fruits (Fig. 4), although there was no evidence of an interaction.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Both unweighted and weighted meta-analyses detected significantly higher concentrations of total carbohydrates and significantly lower concentrations of proteins, amino acids and fibre in organic crops/crop-based compound foods.

    “Both unweighted and weighted meta-analyses detected significantly higher concentrations of total carbohydrates and significantly lower concentrations of proteins, amino acids and fibre in organic crops/crop-based compound foods (Fig. 3).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Unweighted meta-analysis yielded similar results to standard weighted meta-analysis for antioxidant/(poly)phenolics, except no significant difference for total flavonoids and only trends for flavanones and flavones.

    “The unweighted meta-analysis yielded similar results, except for (1) total flavonoids, for which no significant difference was detected, and (2) flavanones and flavones, for which only trends towards higher concentrations in organic crops were detected (Fig. 3).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    For the Trolox equivalent antioxidant capacity assay, similar results were obtained with both the standard weighted and unweighted meta-analyses.

    “similar results were obtained for the Trolox equivalent antioxidant capacity assay with both the standard weighted and unweighted meta-analyses”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • Classified as probably not a substantial claim. May combine two claims.

    Findingreasoning

    In contrast to previous literature reviews, the larger number of studies now available allowed separate meta-analyses to be carried out for different crop types (e.g. fruits, vegetables and cereals), but only for a limited number of composition parameters.

    “In contrast to previous literature reviews( 19 – 21 ), the larger number of studies now available allowed separate meta-analyses to be carried out for different crop types (e.g. fruits, vegetables and cereals), but only for a limited number of composition parameters.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

      Not checked in the free run.

    • cites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source

      Not checked in the free run.

    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

  • May combine two claims.

    Findingreasoning

    Overall assessment of the strength of evidence for antioxidant/(poly)phenolic parameters indicated high or moderate reliability for thirteen of the nineteen parameters and moderate reliability for Cd.

    “Overall assessment of the strength of evidence for antioxidant/(poly)phenolic parameters indicated high or moderate reliability for thirteen of the nineteen parameters and moderate reliability for Cd.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    There is a lack of studies comparing pesticide residue levels in organic and conventional crops, and there has been very little effort taken to re-analyse and then publish available comparative data from food surveillance surveys.

    “Particularly, there is a lack of studies comparing pesticide residue levels in organic and conventional crops, and there has been very little effort taken to re-analyse and then publish available comparative data from food surveillance surveys (e.g. the regular pesticide residue and food composition surveys carried out by the European Food Safety Authority and national agencies in Europe and”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    The present study identified deficiencies in a large proportion of the published studies, including a lack of standardised measurements and a lack of reporting (particularly non-reporting of measures of variability and/or replication) for many composition parameters, and evidence of duplicate or selective reporting of data collected in experiments, which may lead to publication bias.

    “The present study identified deficiencies in a large proportion of the published studies. These included a lack of standardised measurements and a lack of reporting (and, in particular, the non-reporting of measures of variability and/or replication) for many composition parameters, and there was evidence of duplicate or selective reporting of data collected in experiments, which may lead to”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Premisecitation

    Several systematic literature reviews have recently analysed available published information, using both qualitative and quantitative methods, with the aim of identifying potential effects of organic and conventional production protocols on the nutritional quality of crops.

    “Several systematic literature reviews have recently analysed the available published information, using both qualitative and quantitative methods, with the aim of identifying the potential effects of organic and conventional production protocols on the nutritional quality of crops( 19 – 21 ).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

      Not checked in the free run.

    • cites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source

      Not checked in the free run.

    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Organic and conventional crop production may differ significantly in crop rotation designs and fertilisation and crop protection protocols as well as in the type of crop varieties used.

    “As a result, organic and conventional crop production may differ significantly in crop rotation designs and fertilisation and crop protection protocols as well as in the type of crop varieties used( 6 – 10 ).”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [6] Hansen AL (2010) The Organic Farming Manual: A Comprehensive Guide to Starting and Running a Certified Organic Farm. North Adams, MA: Storey Books

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source

      Not checked in the free run.

    • cites [8] van Bueren ETL, Jones SS, Tamm L, et al. (2011) The need to breed crop varieties suitable for organic farming, using wheat, tomato and broccoli as examples: a review. NJAS Wageningen J Life Sci 58, 193– 205

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [9] Tetard-Jones C, Edwards M, Rempelos L, et al. (2013) Effects of previous crop management, fertilization regime and water supply on potato tuber proteome and yield. Agronomy 3, 59– 85 source

      Not checked in the free run.

    • cites [10] Rempelos L, Cooper J, Wilcockson S, et al. (2013) Quantitative proteomics to study the response of potato to contrasting fertilisation regimes. Mol Breed 31, 363– 378 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than non-organic comparators across regions and production seasons.

    “In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production seasons.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
    • Rests on an assumption: The included studies are representative of organic and conventional crop production across regions and production seasons.
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    An overall assessment of the strength of evidence was made using an adaptation of the GRADE system.

    “An overall assessment of the strength of evidence was made using an adaptation of the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system( 41 ).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] Guyatt GH, Oxman AD, Vist GE, et al. (2008) GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ 336, 924– 926 18436948 PMC2335261

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Premisecitation

    Weighted meta-analyses are widely regarded as the most appropriate statistical approach for comparing data sets from studies with variable experimental designs.

    “Weighted meta-analyses are widely regarded as the most appropriate statistical approach for comparing data sets from studies with variable experimental designs( 25 , 26 ).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [25] Stewart G (2010) Meta-analysis in applied ecology. Biol Lett 6, 78– 81 19776064 PMC2817246 source

      Not checked in the free run.

    • cites [26] Koricheva J & Gurevitch J (2013) Place of meta-analysis among other methods of research synthesis. In Handbook of Meta-Analysis in Ecology and Evolution, [ Koricheva J, Gurevitch J and Mengersen K, editors]. Princeton, NJ: Princeton University Press source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The switch from mineral to organic fertilisers results in significant differences in gene and protein expression patterns and, as a result, in secondary metabolite profiles; approximately 10% of proteins have been found to be either up- or down-regulated in response to contrasting fertiliser inputs in potato and wheat.

    “Recent studies have shown that the switch from mineral to organic fertilisers results in significant differences in gene and protein expression patterns and, as a result, in secondary metabolite profiles; for example, approximately 10 % of proteins have been found to be either up- or down-regulated in response to contrasting fertiliser inputs in potato and wheat( 10 – 15 ).”
    Quote in the paperNot a substantial claim0 of 6 sources checked
    • cites [10] Rempelos L, Cooper J, Wilcockson S, et al. (2013) Quantitative proteomics to study the response of potato to contrasting fertilisation regimes. Mol Breed 31, 363– 378 source

      Not checked in the free run.

    • cites [11] Lehesranta SJ, Koistinen KM, Massat N, et al. (2007) Effects of agricultural production systems and their components on protein profiles of potato tubers. Proteomics 7, 597– 604 17309105 source

      Not checked in the free run.

    • cites [12] Tetard-Jones C, Shotton PN, Rempelos L, et al. (2013) Quantitative proteomics to study the response of wheat to contrasting fertilisation regimes. Mol Breed 31, 379– 393 source

      Not checked in the free run.

    • cites [13] van Dijk JP, Cankar K, Scheffer SJ, et al. (2009) Transcriptome analysis of potato tubers – effects of different agricultural practices. J Agric Food Chem 57, 1612– 1623 19173602 source

      Not checked in the free run.

    • cites [14] van Dijk JP, Leifert C, Barros E, et al. (2010) Gene expression profiling for food safety assessment: examples in potato and maize. Regul Toxicol Pharmacol 58, Suppl. 3, S21– S25 20600454 source

      Not checked in the free run.

    • cites [15] van Dijk JP, Cankar K, Hendriksen PJM, et al. (2012) The identification and interpretation of differences in the transcriptomes of organically and conventionally grown potato tubers. J Agric Food Chem 60, 2090– 2101 22300527 source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Previous systematic reviews had methodological limitations: they used different methodologies and inclusion criteria, did not cover most of the large amount of information published in the last 4-5 years, provided no structured assessment of the strength of the evidence presented, and came to contrasting conclusions.

    “However, these systematic reviews (1) used different methodologies (e.g. weighted and unweighted meta-analyses) and inclusion criteria, (2) did not cover most of the large amount of information published in the last 4–5 years, (3) provided no structured assessment of the strength of the evidence presented, and (4) came to contrasting conclusions.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

      Not checked in the free run.

    • cites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source

      Not checked in the free run.

    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

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

    Study design and conductown data

    Data extracted by the two reviewers were compared; discrepancies were detected for approximately 2% of the data extracted and corrected by repeating data extraction.

    “Data extracted by the two reviewers were then compared. Discrepancies were detected for approximately 2 % of the data extracted, and in these cases, data extraction was repeated to correct mistakes.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given

    Publications were assessed for eligibility and data were independently extracted from them by two reviewers.

    “Publications were assessed for eligibility and data were independently extracted from them by two reviewers.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Premisereasoning

    There is still considerable controversy as to whether the use of organic production standards results in significant and consistent changes in the concentrations of potentially health-promoting and potentially harmful compounds in crops and crop-based foods.

    “As a result, there is still considerable controversy as to whether the use of organic production standards results in significant and consistent changes in the concentrations of potentially health-promoting (e.g. antioxidants, (poly)phenolics, vitamins and certain minerals) and potentially harmful (e.g. Cd and Pb) compounds in crops and crop-based foods( 7 , 19 – 22 ).”
    Quote in the paperSubstantial claim0 of 5 sources checked
    • cites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source

      Not checked in the free run.

    • cites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

      Not checked in the free run.

    • cites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source

      Not checked in the free run.

    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

    • cites [22] Benbrook C, Zhao X, Davies N, et al. (2008) New evidence confirms the nutritional superiority of plant-based organic foods. http://organic-center.org/reportfiles/NutrientContentReport.pdf (accessed June 2014)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

    Premisecitation

    Some studies have used unweighted analytical methods to avoid the loss of information associated with conducting weighted meta-analyses on a subset of the available information.

    “However, some studies have used unweighted analytical methods( 19 ) to avoid the loss of information associated with conducting weighted meta-analyses on a subset of the available information.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

      Not checked in the free run.

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

    Study design and conductcitation

    Funnel plots, Egger tests of funnel plot asymmetry and fail-safe number tests were used to assess publication bias.

    “Funnel plots, Egger tests of funnel plot asymmetry and fail-safe number tests were used to assess publication bias( 37 )”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] Rothstein HR, Sutton AJ & Borenstein M (2006) Publication Bias in Meta-Analysis. Chichester, UK: John Wiley & Sons Ltd source

      Not checked in the free run.

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

    Study design and conductnone given

    Tests of homogeneity (Q statistics and I2 statistics) were carried out on all summary effect sizes.

    “We carried out tests of homogeneity (Q statistics and I 2 statistics) on all the summary effect sizes.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Higher antioxidant concentrations and lower Cd concentrations are linked to specific agronomic practices (e.g. non-use of mineral N and P fertilisers, respectively) prescribed in organic farming systems.

    “There is evidence that higher antioxidant concentrations and lower Cd concentrations are linked to specific agronomic practices (e.g. non-use of mineral N and P fertilisers, respectively) prescribed in organic farming systems.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.
  • May combine two claims.

    Interpretationreasoning

    A switch from conventional to organic crop consumption would result in a 20-40% (and for some compounds more than 60%) increase in crop-based antioxidant/(poly)phenolic intake levels without a simultaneous increase in energy.

    “Based on the differences reported, results indicate that a switch from conventional to organic crop consumption would result in a 20–40 % (and for some compounds more than 60 %) increase in crop-based antioxidant/(poly)phenolic intake levels without a simultaneous increase in energy, which would be in line with the dietary recommendations( 16 , 17 ).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [16] Del Rio D, Rodriguez-Mateos A, Spencer JPE, et al. (2013) Dietary (poly)phenolics in human health: structures, bioavailability, and evidence of protective effects against chronic diseases. Antioxid Redox Signal 18, 1818– 1892 22794138 PMC3619154 source

      Not checked in the free run.

    • cites [17] Wahlqvist ML (2013) Antioxidant relevance to human health. Asia Pac J Clin Nutr 22, 171– 176 23635359 source

      Not checked in the free run.

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

    Premisenone given

    Most previous studies did not use weighted meta-analyses based on SMD.

    “In addition, most of the previous studies did not use weighted meta-analyses based on SMD.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The factorial animal study demonstrated that composition differences were mainly linked to contrasting fertilisation regimens.

    “The study also demonstrated that composition differences were mainly linked to contrasting fertilisation regimens (green and animal manures v. mineral fertiliser inputs).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [46] Srednicka-Tober D, Baranski M, Gromadzka-Ostrowska J, et al. (2013) Effect of crop protection and fertilization regimes used in organic and conventional production systems on feed composition and physiological parameters in rats. J Agric Food Chem 61, 1017– 1029 23323826 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A recent factorial animal study yielded composition results similar to the present meta-analyses: rat feeds from organic crops had lower proteins and Cd, higher polyphenols and lutein.

    “With respect to composition differences, the study yielded results similar to those of the meta-analyses carried out in the present study. For example, rat feeds produced from organic crops had lower concentrations of proteins and Cd, but higher concentrations of polyphenols and the carotenoid lutein.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [46] Srednicka-Tober D, Baranski M, Gromadzka-Ostrowska J, et al. (2013) Effect of crop protection and fertilization regimes used in organic and conventional production systems on feed composition and physiological parameters in rats. J Agric Food Chem 61, 1017– 1029 23323826 source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    Overall assessment using adapted GRADE highlighted uncertainties but overall strength of evidence was moderate or high for majority of parameters for which significant differences were detected.

    “The overall assessment of the strength of evidence using an adapted GRADE( 41 ) approach highlighted uncertainties in the evidence base, but the overall strength of evidence was moderate or high for the majority of parameters for which significant differences were detected (see Table 1 and online supplementary Table S13).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [41] Guyatt GH, Oxman AD, Vist GE, et al. (2008) GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ 336, 924– 926 18436948 PMC2335261

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    It is not possible to definitively attribute discrepancies between large precise studies and small imprecise studies to publication bias, which remains strongly suspected rather than detected where asymmetry is severe.

    “However, it is not possible to definitively attribute discrepancies between large precise studies and small imprecise studies to publication bias, which remains strongly suspected rather than detected where asymmetry is severe (see Table 1 and online supplementary Table S13).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationown data

    Results indicated that organic crops and processed crop-based foods have higher antioxidant activity and contain higher concentrations of a wide range of nutritionally desirable antioxidants/(poly)phenolics, but lower concentrations of Cd.

    “The results of meta-analyses of the extensive data set of 343 peer-reviewed publications indicated that organic crops and processed crop-based foods have a higher antioxidant activity and contain higher concentrations of a wide range of nutritionally desirable antioxidants/(poly)phenolics, but lower concentrations of the potentially harmful, toxic metal Cd.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Crop management practices rather than the certification process affect crop performance and composition.
    • Rests on an assumption: Biodynamic standards comply with the legal European Union organic farming standards.
  • May combine two claims.

    Premisecitation

    There are only two human dietary intervention studies in which contrasting antioxidant/(poly)phenolic intake levels were generated by conventional and organic diets; both were inconclusive regarding health impacts.

    “There are, to our knowledge, only two human dietary intervention studies in which contrasting antioxidant/(poly)phenolic intake levels were generated by providing diets based on conventional and organic crops; both studies focused on assessing antioxidant status in humans and were inconclusive with respect to the identification of potential health impacts of organic food consumption( 21 , 42 , 43”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

    • cites [42] Grinder-Pedersen L, Rasmussen SE, Bügel S, et al. (2003) Effect of diets based on foods from conventional versus organic production on intake and excretion of flavonoids and markers of antioxidative defense in humans. J Agric Food Chem 51, 5671– 5676 12952417 source

      Not checked in the free run.

    • cites [43] Søltoft M, Bysted A, Madsen KH, et al. (2011) Effects of organic and conventional growth systems on the content of carotenoids in carrot roots, and on intake and plasma status of carotenoids in humans. J Sci Food Agric 91, 767– 775 21213256 source

      Not checked in the free run.

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

    Interpretationreasoning

    Higher concentrations of (poly)phenolics in organic crops may be due to higher incidence/severity of pest and disease damage, causing enhanced production as part of inducible resistance.

    “Therefore, higher concentrations of (poly)phenolics in organic crops may be due to higher incidence/severity of pest and disease damage, causing enhanced (poly)phenolic production as part of the inducible plant resistance response.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    In Dangour et al. (19), published data from surveys and field experiments were not included in meta-analyses, reducing number of data sets and sensitivity.

    “In the study carried out by Dangour et al. ( 19 ), published data from (1) surveys in which the organic samples were produced to ‘biodynamic-organic’ standards and (2) field experiments investigating associations between organic and conventional production protocols and crop composition were not included in the meta-analyses. This would have further reduced the number of data sets and sensitivity”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [19] Dangour AD, Dodhia SK, Hayter A, et al. (2009) Nutritional quality of organic foods: a systematic review. Am J Clin Nutr 90, 680– 685 19640946 source

      Not checked in the free run.

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

    Interpretationreasoning

    There is still a lack of knowledge about potential human health impacts of increasing antioxidant/(poly)phenolic intake levels and switching to organic food consumption.

    “However, it is important to point out that there is still a lack of knowledge about the potential human health impacts of increasing antioxidant/(poly)phenolic intake levels and switching to organic food consumption.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    Smith-Spangler et al. (21) reported that of 77 comparative data sets (from 15 publications), 21 indicated significantly lower and only 1 significantly higher Cd concentrations in organic foods.

    “Similar to the results of the present study, a recent literature review by Smith-Spangler et al. ( 21 ) has also reported that of the seventy-seven comparative data sets (extracted from fifteen publications), twenty-one indicated significantly lower and only one significantly higher Cd concentrations in organic foods.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Differences in Cd contamination levels between organic and conventional winter wheat are mainly linked to differences in fertilisation regimens (especially high mineral P inputs in conventional systems), although contrasting rotation designs also contributed.

    “Differences in Cd contamination levels between organic and conventional winter wheat have recently been shown to be mainly linked to differences in fertilisation regimens (especially the high mineral P inputs used in conventional farming systems), although contrasting rotation designs also contributed to differences in Cd concentrations between organic and conventional wheat( 7 ).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The higher [nitrate/nitrite] concentrations in conventional crops are thought to be linked to high mineral N inputs, as both [nitrate/nitrite] are known to accumulate in plants under high-mineral N input regimens.

    “The higher and concentrations in conventional crops are also thought to be linked to high mineral N inputs, as both and are known to accumulate in plants under high-mineral N input regimens( 65 ).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [65] McKnight GM, Duncan CW, Leifert C, et al. (1999) Dietary nitrate in man: friend or foe? Br J Nutr 81, 349– 358 10615207 source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Cd accumulates in the human body, especially in the liver and kidneys.

    “Cd accumulates in the human body (especially in the liver and kidneys) and therefore dietary Cd intake levels should be kept as low as possible( 53 ).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [53] European Commission (2008) Commission Regulation (EC) No. 629/2008 of 2 July 2008 amending Regulation (EC) No. 1881/2006 setting maximum levels for certain contaminants in foodstuffs. Off J Eur Union L 173, 6– 9

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    There is variation between crop types with respect to whether the production system has a significant effect and/or the magnitude of difference between organic and conventional crops, although sample sizes remain insufficient to detect interactions between crop types in many cases.

    “This demonstrates that there is variation between crop types with respect to (1) whether the production system has a significant effect and/or (2) the magnitude of difference between organic and conventional crops, although sample sizes remain insufficient to detect interactions between crop types in many cases.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    Higher [nitrate/nitrite] concentrations in conventional crops/crop-based foods are risk factors for stomach cancer and methaemoglobinaemia in humans.

    “The higher concentrations in conventional crops/crop-based foods are nutritionally undesirable, as they have been described to be risk factors for stomach cancer and methaemoglobinaemia in humans( 65 ).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [65] McKnight GM, Duncan CW, Leifert C, et al. (1999) Dietary nitrate in man: friend or foe? Br J Nutr 81, 349– 358 10615207 source

      Not checked in the free run.

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

    Study design and conductcitation

    Care should be taken when interpreting MPD values, as they do not take variability in the precision of individual studies into account and provide less precise estimates of effect than weighted estimates.

    “However, care should be taken when interpreting MPD values, as they do not take variability in the precision of individual studies into account( 25 ) and provide less precise estimates of effect than weighted estimates.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [25] Stewart G (2010) Meta-analysis in applied ecology. Biol Lett 6, 78– 81 19776064 PMC2817246 source

      Not checked in the free run.

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

    Premisecitation

    There is still controversy about the potential health impacts of crop-based [nitrate/nitrite] dietary intake.

    “However, while increasing dietary intake levels is widely considered to be potentially harmful for human health, there is still controversy about the potential health impacts of crop-based dietary intake( 65 – 67 ).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [65] McKnight GM, Duncan CW, Leifert C, et al. (1999) Dietary nitrate in man: friend or foe? Br J Nutr 81, 349– 358 10615207 source

      Not checked in the free run.

    • cites [66] Lundberg JO, Weitzberg E & Gladwin MT (2008) The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics. Nat Rev Drug Discov 7, 156– 167 18167491 source

      Not checked in the free run.

    • cites [67] Machha A & Schechter AN (2012) Inorganic nitrate: a major player in the cardiovascular health benefits of vegetables? Nutr Rev 70, 367– 372 22646129 PMC3367800 source

      Not checked in the free run.

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

    Premisecitation

    Both genetic and environmental/agronomic factors are known to affect the concentrations of N, [nitrate/nitrite], proteins, sugars, antioxidants/(poly)phenolics, Cd and pesticides in crops.

    “This is not surprising as both genetic and environmental/agronomic factors are known to affect the concentrations of N, , , proteins, sugars, antioxidants/(poly)phenolics, Cd and pesticides in crops( 7 , 9 – 12 , 20 , 47 – 52 , 62 ).”
    Quote in the paperNot a substantial claim0 of 10 sources checked
    • cites [7] Cooper J, Sanderson R, Cakmak I, et al. (2011) Effect of organic and conventional crop rotation, fertilization, and crop protection practices on metal contents in wheat (Triticum aestivum). J Agric Food Chem 59, 4715– 4724 21495704 source

      Not checked in the free run.

    • cites [9] Tetard-Jones C, Edwards M, Rempelos L, et al. (2013) Effects of previous crop management, fertilization regime and water supply on potato tuber proteome and yield. Agronomy 3, 59– 85 source

      Not checked in the free run.

    • cites [10] Rempelos L, Cooper J, Wilcockson S, et al. (2013) Quantitative proteomics to study the response of potato to contrasting fertilisation regimes. Mol Breed 31, 363– 378 source

      Not checked in the free run.

    • cites [11] Lehesranta SJ, Koistinen KM, Massat N, et al. (2007) Effects of agricultural production systems and their components on protein profiles of potato tubers. Proteomics 7, 597– 604 17309105 source

      Not checked in the free run.

    • cites [12] Tetard-Jones C, Shotton PN, Rempelos L, et al. (2013) Quantitative proteomics to study the response of wheat to contrasting fertilisation regimes. Mol Breed 31, 379– 393 source

      Not checked in the free run.

    • cites [20] Brandt K, Leifert C, Sanderson R, et al. (2011) Agroecosystem management and nutritional quality of plant foods: the case of organic fruits and vegetables. Crit Rev Plant Sci 30, 177– 197 source

      Not checked in the free run.

    • cites [47] Nicholson RL & Hammerschmidt R (1992) Phenolic compounds and their role in disease resistance. Annu Rev Phytopathol 30, 369– 389 source

      Not checked in the free run.

    • cites [48] Bennett RN & Wallsgrove RM (1994) Secondary metabolites in plant defense mechanisms. New Phytol 127, 617– 633 33874382 source

      Not checked in the free run.

    • cites [49] Almuayrifi M (2013) Effect of fertilisation, crop protection, pre-crop and variety choice on yield of phenols content diseases severity and yield of winter wheat. PhD Thesis, Newcastle University.

      Not checked in the free run.

    • cites [50] Sander JF & Heitefuss R (1998) Susceptibility to Erysiphe graminis f. sp. tritici and phenolic acid content of wheat as influenced by different levels of nitrogen fertilization. J Phytopathol 146, 495– 507 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    There is still scientific controversy about the safety of some currently permitted pesticides (e.g. organophosphorus compounds) even at levels below the MRL and complex mixtures of pesticides, as additive/synergistic effects of pesticide mixtures have been documented and safety testing of pesticide mixtures is currently not required.

    “There is still scientific controversy about the safety of some currently permitted pesticides (e.g. organophosphorus compounds) even at levels below the MRL and complex mixtures of pesticides, as additive/synergistic effects of pesticide mixtures have been documented and safety testing of pesticide mixtures is currently not required as part of the regulatory pesticide approval process( 58 – 60 ).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [58] Marinovich M, Ghilardi F & Galli CL (1996) Effect of pesticide mixtures on in vitro nervous cells: comparison with single pesticides. Toxicology 108, 201– 206 8658539 source

      Not checked in the free run.

    • cites [59] Pape-Lindstrom PA & Lydy MJ (1997) Synergistic toxicity of atrazine and organophosphate insecticides contravenes the response addition mixture model. Environ Toxicol Chem 16, 2415– 2420 source

      Not checked in the free run.

    • cites [60] Axelrad JC, Howard CV & McLean WG (2002) Interactions between pesticides and components of pesticide formulations in an in vitro neurotoxicity test. Toxicology 173, 259– 268 11960678 source

      Not checked in the free run.

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

    Premisecitation

    Pesticide residues below the MRL set by the European Commission are considered by regulators not to pose risk to consumers or the environment, as they are significantly lower than concentrations for which negative health or environmental impacts can be detected in regulatory safety testing.

    “Pesticide residues that are below the MRL set by the European Commission( 55 , 56 ) are considered by regulators not to pose risk to consumers or the environment, as they are significantly lower than concentrations for which negative health or environmental impacts can be detected in the regulatory pesticide safety testing carried out as part of the pesticide approval process( 55 ).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [55] European Commission (2005) Commission Regulation (EC) No. 396/2005 of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC. Off J Eur Union L 70, 1– 16

      Not checked in the free run.

    • cites [56] European Food Safety Authority (2013) Maximum Residue Levels http://www.efsa.europa.eu/en/pesticides/mrls.htm (accessed accessed September 2013).

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The nutritional significance/relevance of slightly lower protein and amino acid concentrations in organic crops to human health is likely to be low, and the lower protein and amino acid concentrations found in organic foods are unlikely to have a significant nutritional or health impact.

    “The nutritional significance/relevance of slightly lower protein and amino acid concentrations in organic crops to human health is likely to be low, as European and North American diets typically provide sufficient or even excessive amounts of proteins and essential amino acids.”
    • Also stated in: § Proteins, amino acids, nitrogen and nitrate/nitrite · hedged
      “Therefore, the lower protein and amino acid concentrations found in organic foods are unlikely to have a significant nutritional or health impact.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: European and North American diets typically provide sufficient or even excessive amounts of proteins and essential amino acids.
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Previous studies have linked lower protein concentrations to lower N inputs and N availability in organic crop production systems.

    “The concentrations of proteins, amino acids and N (which are known to be positively correlated in plants) were found to be lower in organic crops, and this is consistent with the results of previous studies that have linked lower protein concentrations to lower N inputs and N availability in organic crop production systems( 61 , 62 ).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [61] Lueck L, Schmidt C, Cooper J, et al. (2006) Effect of organic, low-input and conventional production systems on yield and quality of winter wheat. Aspects Appl Biol 80, 135– 140 source

      Not checked in the free run.

    • cites [62] Bilsborrow P, Cooper J, Tetard-Jones C, et al. (2013) The effect of organic and conventional crop production systems on the yield and quality of wheat (Triticum aestivum) grown in a long-term field trial. Eur J Agron 51, 71– 80 source

      Not checked in the free run.

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

    Interpretationreasoning

    The higher frequency of detectable residues in conventional fruits than vegetables may indicate higher levels of crop protection inputs in fruit crops, but could also be due to more persistent chemicals, different sprayer technologies, and/or applications closer to harvest.

    “The considerably higher frequency of occurrence of detectable residues in conventional fruits (75 %) than in vegetables (32 %) may indicate higher levels of crop protection inputs being used in fruit crops, but could also have been due to the use of more persistent chemicals, different sprayer technologies used and/or pesticide applications being made closer to harvest.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Previous studies concluded that organic food consumption can reduce exposure to pesticide residues.

    “This supports previous studies that have concluded that organic food consumption can reduce exposure to pesticide residues( 21 – 23 ).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

    • cites [22] Benbrook C, Zhao X, Davies N, et al. (2008) New evidence confirms the nutritional superiority of plant-based organic foods. http://organic-center.org/reportfiles/NutrientContentReport.pdf (accessed June 2014)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [23] Curl C, Fenske RA & Elgethun K (2003) Organophosphorus pesticide exposure of urban and suburban preschool children with organic and conventional diets. Environ Health Perspect 111, 377– 382 12611667 PMC1241395 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In recent EFSA surveys, pesticide residues above the MRL were found in 6.2% of spinach, 3.8% of oat, 3.4% of peach, 3.0% of orange, 2.9% of strawberry and lettuce, 2.8% of table grape, and 2.7% of apple samples analysed.

    “For example, in recent European Food Safety Authority surveys, pesticide residues above the MRL have been found in 6·2 % of spinach, 3·8 % of oat, 3·4 % of peach, 3·0 % of orange, 2·9 % of strawberry and lettuce, 2·8 % of table grape and 2·7 % of apple samples analysed( 57 ).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [57] European Food Safety Authority (2011) The 2009 European Union report on pesticide residues in food. EFSA 9, 2430 source

      Not checked in the free run.

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

    Premisecitation

    A range of soil (e.g. pH) and agronomic (e.g. liming) factors affect Cd concentrations in crops.

    “A range of other soil (e.g. pH) and agronomic (e.g. liming) factors are known to affect Cd concentrations in crops( 54 ), and these may explain the variability in results between individual comparative studies, crop species and crop types (see Fig. 4 and online supplementary Figs. S4 and S22).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] Bešter PK, Lobnik F, Eržen I, et al. (2013) Prediction of cadmium concentration in selected home-produced vegetables. Ecotoxicol Environ Saf 96, 182– 190 23886800 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    This supports the conclusion that future research would likely be confirmatory.

    “This supports the conclusion that future research would likely be confirmatory.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Cd is a highly toxic metal and one of only three toxic metal contaminants (Pb, Hg) for which the European Commission has set maximum residue levels in foods.

    “Cd is a highly toxic metal and one of the only three toxic metal contaminants (the other two being Pb and Hg) for which the European Commission has set maximum residue levels (MRL) in foods( 53 ).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [53] European Commission (2008) Commission Regulation (EC) No. 629/2008 of 2 July 2008 amending Regulation (EC) No. 1881/2006 setting maximum levels for certain contaminants in foodstuffs. Off J Eur Union L 173, 6– 9

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation

    Smith-Spangler et al. (21) concluded that the currently available data do not allow clear trends with respect to health markers and outcomes to be identified.

    “However, they concluded that the currently available data do not allow clear trends with respect to health markers and outcomes to be identified.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

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

    Interpretationreasoning

    Diet composition may have an effect on the relative impact of switching from conventional to organic food consumption.

    “Diet composition may have an effect on the relative impact of switching from conventional to organic food consumption, and this should be considered in the design of such studies.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A recent review by Smith-Spangler et al. (21) analysed the results of fourteen studies in which the effects of organic and conventional food consumption on clinical outcomes and health markers were studied.

    “A recent review by Smith-Spangler et al. ( 21 ) has analysed the results of fourteen studies in which the effects of organic and conventional food (both crop and livestock product) consumption on clinical outcomes (e.g. allergic symptoms and Campylobacter infections) and health markers (e.g. serum lipid and vitamin concentrations) were studied.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] Smith-Spangler C, Brandeau ML, Hunter GE, et al. (2012) Are organic foods safer or healthier than conventional alternatives? A systematic review. Ann Intern Med 157, 348– 366 22944875 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    The relative impact of switching from conventional to organic food consumption could be expected to be smaller for diets with high amounts of (poly)phenolic-rich foods.

    “For example, the relative impact of switching from conventional to organic food consumption could be expected to be smaller for diets with high amounts of (poly)phenolic-rich foods.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationown data

    There is now evidence from a large number of quality studies that consistently show that organic production systems result in crops/crop-based compound foods with higher concentrations of antioxidants/(poly)phenolics and lower concentrations of Cd and pesticide residues compared with conventional production systems.

    “However, there is now evidence from a large number of quality studies that consistently show that organic production systems result in crops/crop-based compound foods with higher concentrations of antioxidants/(poly)phenolics and lower concentrations of Cd and pesticide residues compared with conventional production systems.”
    Quote in the paperSubstantial claim
73 of 73
  • The paper relies on this without support.

    The organic status of crops in the included studies (as reported by authors or labels) accurately reflects organic production standards.

    “Data from all the three types of studies were deemed relevant for the meta-analyses if the authors stated that (1) organic farms included in farm surveys were using organic farming methods, (2) organic products collected in retail surveys were labelled as organic, and (3) organic plots used in EX were managed according to organic farming standards.”
  • The paper relies on this without support.

    The included studies are representative of organic and conventional crop production across regions and production seasons.

    “Approximately 70 % of all the studies included in the meta-analyses were carried out in Europe, mainly in Italy, Spain, Poland, Sweden, the Czech Republic, Switzerland, Turkey, Denmark, Finland and Germany, with most of the remaining studies being carried out in the USA, Brazil, Canada and Japan”
  • The paper relies on this without support.

    Peer review is a valid quality selection criterion for included studies.

    “Only four non-peer-reviewed papers with suitable data sets were identified but subsequently rejected, as the small number minimised any potential bias( 28 ) from using peer review as a ‘quality’ selection criterion.”
  • The authors state this as an assumption.

    Crop management practices rather than the certification process affect crop performance and composition.

    “the crop management practices rather than the certification process were assumed to affect crop performance and composition.”
  • The paper relies on this without support.

    Biodynamic standards comply with the legal European Union organic farming standards.

    “as biodynamic standards comply with the legal European Union organic farming standards.”
  • The paper relies on this without support.

    European and North American diets typically provide sufficient or even excessive amounts of proteins and essential amino acids.

    “as European and North American diets typically provide sufficient or even excessive amounts of proteins and essential amino acids.”
6 of 6

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?

  • Compared with conventionally grown foods, organically grown foods can contain higher concentrations of phenolic compounds and fewer pesticide residues, but have similar nutrient profiles in many other respects.

    “Compared with conventionally grown foods, organically grown foods can contain higher concentrations of phenolic compounds and fewer pesticide residues; yet, they also have similar nutrient profiles in many other respects.124-126”

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.

  • Conflicting significance results for chlorogenic acid

    Minor

    The paper identifies chlorogenic acid as 5-O-caffeoylquinic acid and says the unweighted meta-analysis found a significant difference. It later lists 5-O-caffeoylquinic acid among compounds for which the meta-analyses found no significant difference.

1 of 1

Cites

Flagged first, then by citations

4 of the 71 references couldn’t be matched to a known paper.

Research works printed but not linked: 3

  1. Lampkin, 2002, Organic Farming
  2. 2005, Commission Regulation (EC) No. 396/2005 of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC, Off J Eur Union, 70, 1
  3. 2008, Commission Regulation (EC) No. 629/2008 of 2 July 2008 amending Regulation (EC) No. 1881/2006 setting maximum levels for certain contaminants in foodstuffs, Off J Eur Union, 173, 6

Cited by

Sorted by citations

Authors
Barański, M., Średnicka-Tober, D., Volakakis, N., Seal, C., Sanderson, R., Stewart, G. B., Benbrook, C., Biavati, B., Markellou, E., Giotis, C., Gromadzka-Ostrowska, J., Rembiałkowska, E., Skwarło-Sońta, K., Tahvonen, R., Janovská, D., Niggli, U., Nicot, P., & Leifert, C.
Affiliations
  • Newcastle University (GB)
  • University of Newcastle Australia (AU)
  • Washington State University (US)
  • University of Bologna (IT)
  • Benaki Phytopathological Institute (GR)
  • Technological Educational Institute of the Ionian Islands (GR)
  • Warsaw University of Life Sciences (PL)
  • Agrifood Research Finland (FI)
  • Czech Agrifood Research Center (CZ)
  • Forschungsinstitut für biologischen Landbau (DE)
  • Pathologie végétale (FR)
Corresponding author
Leifert, Carlo
Venue
British Journal of Nutrition
Published
2014-07-15
Volume
112
Issue
5
Pages
794-811
ISSN
  • 0007-1145 (ISSN-L)
  • 1475-2662
OpenAlex
W2119995313
Cited by
684
References
71
Citations by year
2026: 33 · 2025: 56 · 2024: 75 · 2023: 55 · 2022: 72 · 2021: 57 · 2020: 61 · 2019: 38 · 2018: 53 · 2017: 63 · 2016: 64 · 2015: 45 · 2014: 9 · 2012: 2
FWCI
6.91
Type
journal article
Language
en
Open access
Locations
  • British Journal Of Nutrition (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • HAL (acceptedVersion, other-oa)
  • Organic Eprints (International Centre for Research in Organic Food Systems, and Research Institute of Organic Agriculture) (acceptedVersion)
  • Jukuri (Natural Resources Institute Finland (Luke)) (submittedVersion)
  • Archivio istituzionale della ricerca (Alma Mater Studiorum Università di Bologna) (submittedVersion)
  • Newcastle University ePrints (Newcastle Univesity) (cc-by)
Funders
  • Helsingin Yliopisto
  • Newcastle University
Topics
  • Life Sciences › Agricultural and Biological Sciences › Plant Science › Organic Food and Agriculture
  • Health Sciences › Medicine › Biochemistry › Phytochemicals and Antioxidant Activities
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Food and Agricultural Sciences
Keywords
organic farming, antioxidants, polyphenols, cadmium, pesticide residues, flavonoids, anthocyanins, stilbenes, flavonols, flavanones, phenolic acids, nutritional composition, vitamin and mineral content, fertilizer use
MeSH terms
Antioxidants, Cadmium, Flavonoids, Humans, Nutritive Value, Pesticide Residues, Crops, Agricultural, Food, Organic, Organic Agriculture, Polyphenols, Hydroxybenzoates

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.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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