A cross-link between dietary sodium, gut microbiome, and heart failure

Background: Inflammation plays a central role in the development of heart failure (HF). Inflammation can also directly and indirectly modulate the bacterial composition of the human microbiome. Evidence shows high sodium intake contributes to progression of HF through inflammation.  However, the mechanism through which high salt diet influences vascular inflammation in HF has not been fully understood. The purpose to of the study is to examine the relationships between salt intakes and gut bacterial composition in HF patients.

Methods: This is a retrospective study using data collected from 90 HF patients participating cardiac rehabilitation. The daily sodium intake was assessed by 24-hour urine excretion. Fecal samples were collected and gut microbiota was assessed through 16sRNA sequencing. Gut microbiota data and 24-hour urinary sodium excretion were log-transformed and gut microbiota data were further standardized before statistical analysis. Mixed-effects models were used to assess the association of 24-hour urinary sodium excretion with gut microbiota with adjustment of age, race, sex, body mass index, group assignment, visit, and diet.

Results: Gut microbiota were measured in a total of 119 samples from 80 HF patients, who were aged 64.2 ± 10.4 years old, 56% male, and 58% Caucasian. The average ejection fraction (EF) was 46.7 ± 15.4 %. We found a significant correlation between sodium intake and the composition of gut proteobacteria (β = 0.57; P = 0.026) among HF patients.  HF patients who had higher daily sodium intake had increased proportions of proteobacteria in their gastrointestinal (GI) system.

Discussion:

The significant correlation between sodium intake and the increased proportion of proteobacteria may be explained by the direct impact of high sodium intake on the growth of proteobacteria and/or indirect effect through the inflammation process. The inflammatory cells release reactive nitrogen species which are used by proteobacteria for anaerobic respiration and growth. As a result, the growth of proteobacteria is a biomarker of vascular inflammation caused by high sodium intake in HF patients.

Conclusion: The role of gut microbiota in heart failure prognosis may help explain the link between dietary sodium intake and heart failure prognosis. Increased proportions of proteobacteria may be a sensitive indicator of worsening HF caused by high sodium intake. Additional research is needed to support our finding.