The Salty Gut: Effects of High Dietary Salt Intake on the Gut Microbiota

Gut microbiota composition and function has an important role in host physiology. In general, gut microbial diversity is positively correlated with health status. Recent evidence confirms the role of gut dysbiosis in cardiovascular disease. Americans consume 50% more salt than the amount recommended by the Dietary Guidelines and 130% more than recommended by the American Heart Association. Excess salt intake is considered a modifiable risk factor for cardiovascular disease. Changes in the gut microbiota composition followed by immune system activation is reported with high salt intake in animals. In particular, abundance of proinflammatory T helper 17 (Th17) cells increases with excess salt consumption. In contrast, T regulatory (Treg) cells oppose Th17 cell action and may aid in reducing inflammation associated with high salt intake, a hypothesis that has not yet been tested in humans. Only one preliminary study assessed changes in gut bacterial composition with high salt intake in humans, when only men were recruited. The study also found an increase in Th17 cell abundance. Thus, the objective of this study is to investigate the influence of high salt intake on the gut microbiota diversity and Th17 and Treg cell abundance in men and women.

Inclusion criteria

• healthy
• normal blood pressure

Exclusion criteria

• hypertension
• cardiovascular disease
• renal disease
• diabetes
• cancer
• current use of anti-inflammatory agents, glucocorticoids or other immune regulating medications, or certain anti-depressants
• history of intestinal surgery
• inflammatory bowel disease, celiac disease, lactose intolerance, chronic pancreatitis or other malabsorption disorder
• antibiotic use in the past 3 months
• prebiotic, probiotic, or antioxidant supplementation in the past 3 months
• ≥10 lbs weight gain or loss in the past 6 months
• use of tobacco products
• highly trained endurance athletes
• current pregnancy or lactation