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Effects of processed meat and drinking water nitrate on oral and fecal microbial populations in a controlled feeding study

Sinha, R., Zhao, N. ORCID:, Goedert, J. J., Byrd, D. A. ORCID:, Wan, Y., Hua, X., Hullings, A. G., Knight, R., Breda, S. v., Mathijs, K., de Kok, T. M. ORCID:, Ward, M. H., Pieters, H.-J., Sági-Kiss, V., Kuhnle, G. G. ORCID:, Georgiadis, P., Saccani, G., Parolari, G., Virgili, R., Hemke, G. , Hung, Y., Verbeke, W., Masclee, A. A., Vleugels-Simon, C. B., van Bodegraven, A. A., Dobbelaere, D., Vandewynkel, A., van der Kruijk, R., Egberts, F. and van Helvoirt, J.-H. (2021) Effects of processed meat and drinking water nitrate on oral and fecal microbial populations in a controlled feeding study. Environmental Research, 197. 111084. ISSN 0013-9351

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To link to this item DOI: 10.1016/j.envres.2021.111084


Background One mechanism that can explain the link between processed meat consumption and colorectal cancer (CRC) is the production of carcinogenic N-nitroso compounds (NOCs) in the gastrointestinal tract. Oral and gut microbes metabolize ingested proteins (a source of secondary and tertiary amines and amides) and can reduce nitrate to nitrite, generating potentially carcinogenic NOCs. Objective We evaluated whether nitrate/nitrite in processed meat or water influences the fecal or salivary microbiota. Design In this dietary intervention study, 63 volunteers consumed diets high in conventional processed meats for two weeks, switched to diets high in poultry for two weeks, and then consumed phytochemical-enriched conventional processed or low-nitrite processed meat diets for two weeks. During the intervention, they drank water with low nitrate concentrations and consumed a healthy diet with low antioxidants. Then the volunteers drank nitrate-enriched water for 1 week, in combination with one of the four different diets. We measured creatinine-adjusted urinary nitrate levels and characterized the oral and fecal microbiota using 16S rRNA amplicon sequencing. Results Using linear mixed models, we found that, compared to baseline, urinary nitrate levels were reduced during the phytochemical-enriched low-nitrite meat diet (p-value = 0.009) and modestly during the poultry diet (p-value = 0.048). In contrast, urinary nitrate increased after 1-week of drinking nitrate-enriched water (p-value<10−5). Nitrate-enriched water, but not processed meats with or without phytochemicals, altered the saliva microbial population (p-value ≤0.001), and significantly increased abundance of 8 bacterial taxa, especially genus Neisseria and other nitrate-reducing taxa. Meats, phytochemicals and nitrate-enriched water had no significant effects on saliva alpha diversity or any diversity parameter measured for the fecal microbiota. Conclusion These findings support the hypothesis that drinking high nitrate water increases oral nitrate-reducing bacteria, which likely results in increased NOC. However, meat nitrate/nitrite at the levels tested had no effect on either the gut or oral bacteria.

Item Type:Article
Divisions:Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Food Research Group
ID Code:98766

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