Associations between sodium intake and gut microbiota composition

High salt intake is associated with adverse health outcomes. Emerging evidence highlights the importance of the gut microbiome in human health, but large-scale human data on salt intake and the microbiome are limited. We examined the cross-sectional association between estimated 24-h sodium excretion (est24hNa) and the gut microbiome in a population-based cohort.

We included 9,220 participants from the Swedish SCAPIS cohort with available shotgun metagenomic sequencing of fecal samples and urine analyses. We estimated the 24-h sodium excretion using the Kawasaki formula. Alpha diversity was assessed using the Shannon and inverse Simpson indices, and beta diversity using Bray-Curtis dissimilarity. Functional potential was evaluated using Gut Microbial Modules. Associations were analyzed using mixed linear regression models.

Alpha diversity was inversely associated with est24hNa, but associations were attenuated after adjustment for BMI and were not significant in fully adjusted models. Beta diversity was associated with est24hNa, although the explained variance was small (R2 < 0.001). Higher est24hNa was associated with 75 microbial species, including lower abundance of 27 species and higher abundance of oral-associated taxa such as Streptococcus spp. and Veillonella. It was also associated with increased abundance of pathways involved in microbial energy metabolism and carbohydrate fermentation.

Higher est24hNa was associated with selected gut microbiome features, including a higher abundance of several oral-associated taxa and differences in inferred functional capacity for energy metabolism and carbohydrate fermentation. These findings identify microbial patterns associated with sodium exposure that may be relevant to cardiometabolic health.