Impact of Mouthwash-Induced Oral Microbiome Disruption on Alzheimer's Disease Risk: A Perspective Review
Open accessAbstract
The widespread use of mouthwashes, particularly those containing chlorhexidine (CHX), has raised concerns about their impact on the oral microbiome and potential systemic health effects. This perspective review examines the current evidence linking CHX mouthwash use to disruptions in the oral microbiome and explores the potential indirect implications for Alzheimer's disease (AD) risk. CHX mouthwash is effective in reducing dental plaque and gingival inflammation, but it also significantly alters the composition of the oral microbiome, decreasing the abundance of nitrate-reducing bacteria critical for nitric oxide (NO) production. This disruption can lead to increased blood pressure, a major risk factor for AD. Given the established connection between hypertension and AD, the long-term use of CHX mouthwash may indirectly contribute to the onset of AD. However, the relationship between CHX mouthwash use and AD remains largely indirect, necessitating further longitudinal and cohort studies to investigate whether a direct causal link exists. The review aims to highlight the importance of maintaining a balanced oral microbiome for both oral and systemic health and calls for more research into safer oral hygiene practices and their potential impacts on neurodegenerative disease risk.
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Broad-spectrum antibacterial mouthwashes markedly reduce the abundance and activity of oral nitrate-reducing bacteria, leading to lower salivary nitrite formation and diminished NO bioavailability.
“Recent evidence further reinforces this concept by showing that broad-spectrum antibacterial mouthwashes markedly reduce the abundance and activity of these bacteria. This leads to lower salivary nitrite formation and diminished NO bioavailability.”
From Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations (2026) · cites this paper as [108]
The “Effects of chlorhexidine mouthwash on the oral microbiome” section reports that chlorhexidine (CHX) reduces nitrate-reducing bacteria by about 80% and virtually abolishes oral nitrate-reducing capacity. It also links CHX use to lower nitrite availability and reduced nitrate-to-nitrite conversion needed to maintain NO levels. The claim extends these findings to broad-spectrum antibacterial mouthwashes generally, whereas the review says effects vary by formulation and focuses its evidence on CHX. Page numbers were not available in our copy. (LLM, conf=0.82)
Experimental — accuracy not yet measuredProton pump inhibitors and antibacterial mouthwashes may reduce nitrate-nitrite-NO conversion.
“However, proton pump inhibitors and antibacterial mouthwashes may reduce nitrate-nitrite-NO conversion [102,108].”
From Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations (2026) · cites this paper as [108]
The section “Effects of chlorhexidine mouthwash on the oral microbiome” states that CHX mouthwash reduces oral nitrate-to-nitrite conversion, supporting the mouthwash part of the claim. Our copy does not address proton pump inhibitors; searches for that term and “PPI” found no supporting passage. Page numbers were not available in the indexed copy. (LLM, conf=0.88)
Experimental — accuracy not yet measuredAvoiding antibacterial mouthwashes around consumption, ensuring adequate salivary flow, and consuming nitrate-rich beetroot products 1-2 h prior to desired effect can enhance nitrate reduction and NO bioavailability.
“These include avoiding antibacterial mouthwashes around the time of consumption, ensuring adequate salivary flow and consuming nitrate-rich beetroot products 1–2 h prior to the desired physiological effect.”
From Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations (2026) · cites this paper as [108]
The sections on oral microbiome effects and chlorhexidine mouthwash (page numbers unavailable) support consuming nitrate-rich beetroot and avoiding antibacterial mouthwash to preserve oral nitrate reduction. The paper does not recommend ensuring adequate salivary flow or specify consuming beetroot products 1–2 hours before a desired effect. (LLM, conf=0.86)
Experimental — accuracy not yet measuredDietary nitrate can theoretically enhance the vasodilatory effects of pharmacological NO donors by providing additional nitrite-derived NO.
“dietary nitrate can theoretically enhance the vasodilatory effects of pharmacological NO donors by providing additional nitrite-derived NO [29,31,33,108].”
From Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations (2026) · cites this paper as [108]
The section 'Effects of the oral microbiome on nitric oxide production and vascular health' (page not provided) describes dietary nitrate being converted to nitrite and then NO, and explains NO's role in vasodilation. It does not discuss pharmacological NO donors or say that dietary nitrate enhances their vasodilatory effects. (LLM, conf=0.84)
Experimental — accuracy not yet measuredMouthwash-induced oral dysbiosis has been linked to broader systemic effects, including potential neurocognitive consequences.
“Beyond its cardiovascular implications, mouthwash-induced oral dysbiosis has also been linked to broader systemic effects, including potential neurocognitive consequences, as suggested by Boulares et al. [108].”
From Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations (2026) · cites this paper as [108]
Several practical guidelines can enhance nitrate reduction and NO bioavailability.
“there are several practical guidelines that can enhance nitrate reduction and NO bioavailability [29,31,33,108].”
From Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations (2026) · cites this paper as [108]
There is no formal protocol for dietary nitrate intake.
“Although there is no formal protocol for dietary nitrate intake”
From Dietary Nitrate-Rich Vegetables as Natural Modulators of Health: Mechanisms and Benefits in Ageing Populations (2026) · cites this paper as [108]
The section ‘Effects of the oral microbiome on nitric oxide production and vascular health’ describes dietary nitrate sources and recommends a nitrate-rich diet, but does not address whether a formal intake protocol exists. Searches for a formal protocol and for recommended intake guidelines found no passage that settles the claim; page numbers were not provided in our copy. (LLM, conf=0.72)
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- Authors
- Boulares, A., Jdidi, H., & Bragazzi, N. L.
- Affiliations
- Université de Poitiers (FR)
- University of Parma (IT)
- Corresponding author
- Bragazzi, Nicola Luigi
- Venue
- International Dental Journal
- Publisher
- Elsevier BV
- Published
- 2025-02
- Volume
- 75
- Issue
- 1
- Pages
- 45-50
- ISSN
- 0020-6539 (ISSN-L)
- PMC
- PMC11806309
- OpenAlex
- W4403234082
- Cited by
- 11
- References
- 42
- Citations by year
- 2026: 5 · 2025: 6
- FWCI
- 0.89
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- International Dental Journal (publishedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion, cc-by-nc-nd)
- PubMed (publishedVersion)
- HAL (submittedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Topics
- Health Sciences › Dentistry › Periodontics › Oral microbiology and periodontitis research
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gut microbiota and health
- Health Sciences › Dentistry › Periodontics › Dental Health and Care Utilization
- Keywords
- mouthwash, chlorhexidine, oral microbiota, Alzheimer's disease risk, hypertension, nitric oxide, nitrate-reducing bacteria, oral hygiene, neurodegenerative diseases, blood pressure
- MeSH terms
- Alzheimer Disease, Chlorhexidine, Dental Plaque, Humans, Mouth, Mouthwashes, Oral Hygiene, Risk Factors, Microbiota
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