Nutrition Notes

Gut Microbiome and Cardiovascular Health: What We Know About the Gut-Heart Axis

The relationship between the gut microbiome and the heart is referred to as the ‘gut-heart axis.’ Emerging evidence suggests that the gut microbiome–its composition and its metabolites–may influence cardiovascular (CV) health. 

In clinical studies, compositional differences in gut microbiota have been observed in individuals with certain CV illnesses when compared to healthy populations. The abundance of specific microbes has been linked to predictors of coronary artery disease. In one clinical study, the gut microbiome of individuals with coronary atherosclerosis was shown to have significant compositional differences when compared with healthy individuals.

In addition, microbial metabolites such as short-chain fatty acids (SCFAs) have been linked to certain protective effects regarding CV outcomes. SCFAs are the primary energy source for colonocytes, helping maintain gut barrier integrity and intestinal immune balance. Research findings support the hypothesis that sufficient SFCA production may have a positive influence on blood vessel function and blood pressure regulation; they have been shown to bind to certain receptors in the kidney, playing a role in renin secretion, an important molecule in blood pressure regulation. SCFAs have also been shown to maintain the epithelial barrier, reduce sympathetic activity, and support a healthy inflammatory response.

Dysbiosis may also influence parameters related to hypertension. A review article aggregated information on over 15 bacteria including those from the Methanobrevibacter, Oxalobacter, Klebsiella, and Salmonella genera. The authors reported that dysbiosis in the gut associated with these genera may be linked to the presence of hypertension. Other microbes have been associated with the presence of normal blood pressure, including Bifidobacterium, Butyrivibrio, and Coprococcus.

Recent research has linked decreases in intestinal epithelial barrier health and gut microbial imbalances with changes related to CV function. A metagenomic analysis reported significant differences in gut microbial composition when comparing fecal samples from individuals with chronic heart failure with those from a control group.

The body’s inflammatory response is also thought to be an important factor in the gut-heart axis. Metabolites from microbes in the GI tract may also influence the inflammatory response and CV health. An animal study observed increases in colonic Treg cells and factors related to a normal inflammatory response in mice with diets fortified with the SCFAs butyrate and propionate. Decreased levels of SCFAs have been associated with age-related changes and increases in certain parameters related to some CV diseases. Probiotics and plant polysaccharides may also help support gut microbial balance, the increase of SCFA levels, and the reduction of inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α).

A systematic review and meta-analysis explored the effect of probiotic supplementation on blood pressure, pooling data from over two thousand human participants. Significant decreases in both systolic blood pressure (by -3.05 mmHg) and diastolic blood pressure (by -1.51 mmHg) were reported when probiotics were consumed by patients with CV conditions such as hypertension. Probiotics have been shown in a different meta-analysis to improve lipid levels, blood pressure, and inflammation indicators in individuals receiving probiotics for eight weeks. A randomized placebo-controlled twelve-week trial involving species from the Bifidobacterium, Lactobacillus, Lactococcus, Streptococcus, and Enterococcus genera reported reductions in systolic blood pressure, TNF-α, and IL-6 in the presence of 10 billion colony-forming units daily.

While more research is needed, evidence suggests that gut microbial composition may contribute to factors related to inflammatory status, CV health, and the gut-heart axis.

By Dr. Cory Ambrose, ND, MAT