Cited by 56Nutritional Studies and DietNitric Oxide and Endothelin EffectsOral microbiology and periodontitis research

Dietary intake of inorganic nitrate in vegetarians and omnivores and its impact on blood pressure, resting metabolic rate and the oral microbiome

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Ashworth, Ann, Clarke, Craig, Farnham, Garry, Liddle, Luke, Burleigh, Mia, Rodiles, Ana, Sillitti, Carla, Kiernan, Michele +4 more·2019·Free Radical Biology and Medicine

Abstract

Vegetarian diets are commonly associated with lower blood pressure levels. This has been related to greater consumption of inorganic nitrate, since vegetables are the main source of this anion. Dietary nitrate is reduced to nitrite by commensal bacteria in the mouth, which in turn leads to increased circulatory nitrite availability. Nitrite can form nitric oxide by several pathways promoting a reduction in the vascular tone and lower blood pressure. This study tested whether vegetarians have higher concentrations of nitrite in saliva and plasma, and lower blood pressure and resting metabolic rate (RMR), due to higher intakes of nitrate, compared to omnivores. Following a non-randomized, cross-over and single-blinded design we measured dietary nitrate intake, blood pressure and RMR in young and healthy vegetarians (n = 22) and omnivores (n = 19) with similar characteristics after using placebo or antibacterial mouthwash for a week to inhibit oral bacteria. Additionally, we analyzed salivary and plasma nitrate and nitrite concentrations, as well as the oral nitrate-reduction rate and oral microbiome in both groups. Dietary nitrate intake in vegetarians (97 ± 79 mg/day) was not statistically different (P > 0.05) to omnivores (78 ± 47 mg/day). Salivary and plasma nitrate and nitrite concentrations were similar after placebo mouthwash in both groups (P > 0.05). The oral nitrate-reducing capacity, abundance of oral bacterial species, blood pressure and RMR were also similar between vegetarians and omnivores (P > 0.05). Antibacterial mouthwash significantly decreased abundance of oral nitrate-reducing bacterial species in vegetarians (_ 16.9%; P < 0.001) and omnivores (_ 17.4%; P < 0.001), which in turn led to a significant reduction of the oral nitrate-reducing capacity in vegetarians (-78%; P < 0.001) and omnivores (-85%; P < 0.001). However, this did not lead to a significant increase in blood pressure and RMR in either groups (P > 0.05). These findings suggest that vegetarian diets may not alter nitrate and nitrite homeostasis, or the oral microbiome, compared to an omnivore diet. Additionally, inhibition of oral nitrite synthesis for a week with antibacterial mouthwash did not cause a significant raise in blood pressure and RMR in healthy, young individuals independent of diet.

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Crossref · 10.1016/j.freeradbiomed.2019.05.010

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Authors
Ashworth, A., Clarke, C., Farnham, G., Liddle, L., Burleigh, M., Rodiles, A., Sillitti, C., Kiernan, M., Moore, M., Hickson, M., Easton, C., & Bescos, R.
Affiliations
  • University of Plymouth (GB)
  • Bishop Grosseteste University (GB)
  • University of the West of Scotland (GB)
  • National Research Council (IT)
Venue
Free Radical Biology and Medicine
Publisher
Elsevier BV
Published
2019-07
Volume
138
Pages
63-72
ISSN
0891-5849 (ISSN-L)
OpenAlex
W2944126975
Cited by
56
References
61
Citations by year
2026: 7 · 2025: 7 · 2024: 11 · 2023: 6 · 2022: 7 · 2021: 5 · 2020: 10 · 2019: 3
FWCI
5.76
Type
journal article
Language
en
Locations
  • Free Radical Biology and Medicine (publishedVersion)
  • PubMed (publishedVersion)
  • The UWS Academic Portal (University of the West of Scotland) (publishedVersion, cc-by-nc-nd)
  • PEARL (University of Plymouth) (submittedVersion, cc-by-nc-nd)
  • PEARL (University of Plymouth) (submittedVersion, cc-by-nc-sa)
Funders
Plymouth University
Topics
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Nutritional Studies and Diet
  • Health Sciences › Medicine › Physiology › Nitric Oxide and Endothelin Effects
  • Health Sciences › Dentistry › Periodontics › Oral microbiology and periodontitis research
Keywords
inorganic nitrate, dietary nitrate intake, vegetarian diet, omnivorous diet, blood pressure, resting metabolic rate, oral microbiota, nitrite, nitric oxide, antibacterial mouthwash, salivary nitrate, plasma nitrate, nitrate supplementation, nitric oxide synthase inhibition
MeSH terms
Vegetarians, Adolescent, Adult, Basal Metabolism, Blood Pressure, Diet, Female, Humans, Male, Middle Aged, Mouth, Mouthwashes, Nitrates, Nitric Oxide, Nitrites, Oxidation-Reduction, Saliva, Vegetables, Cross-Over Studies, Microbiota, Healthy Volunteers

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