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Vanhaecke T. et al. 2021

Drinking water source and intake are associated with distinct gut microbiota signatures in US and UK populations

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The microbiome of the digestive tract exerts fundamental roles in host physiology. Extrinsic factors including lifestyle and diet are widely recognized as key drivers of gut and oral microbiome compositions. While drinking water is among the food items consumed in the largest amount, little is known about its potential impact on the microbiome.


We explored the associations between plain drinking water source and intake, and gut and oral microbiota compositions in a population-based cohort.


Microbiota, health, lifestyle and food intake data were extracted from the American Gut Project public database. Associations between drinking water source (bottled, tap, filtered, or well water) and intake, and global microbiota composition were evaluated using linear and logistic models adjusted for anthropometric, diet and lifestyle factors in 3413 and 3794 individuals, respectively (fecal samples; 56% female, age 48 [36-59] years; BMI 23.3 [20.9-26.3] kg/m2), and in 283 and 309 individuals, respectively (oral samples).


Drinking water source ranked among the key contributing factors explaining the gut microbiota variation, with 13% (Faith's PD) and 47% (Bray-Curtis dissimilarity) of the age effect size. Drinking water source was associated with differences in gut microbiota signatures, as revealed by beta diversity analyses (P<0.05; Bray-Curtis dissimilarity, Weighted UniFrac distance). Subjects drinking mostly well water had higher fecal alpha diversity (P<0.05; Faith's PD, Observed ASVs), higher Dorea and lower Bacteroides, Odoribacter and Streptococcus than the other groups. Low water drinkers also exhibited gut microbiota differences compared to high water drinkers (P<0.05; Bray-Curtis dissimilarity, Unweighted UniFrac distance) and a higher abundance of Campylobacter. No associations were found between oral microbiota composition and drinking water consumption.


Our results indicate that drinking water may be an important factor in shaping the human gut microbiome and that integrating drinking water source and intake as covariates in future microbiome analyses is warranted.

A word from our expert, Tiphaine Vanhaecke, France:

“This study is the first to show a link between drinking water origin (bottled, tap, filtered, well) and differences in gut microbiota signature. The type of drinking water was one of the key factors explaining gut microbiota composition. The effect size of drinking water source was similar to that of diet type. People drinking well water had a more diverse gut microbiota than the other groups. We also found moderate differences in gut microbiota composition between high and low water drinkers”

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