The Heart-Gut Axis: Are Your Gut-Microbiome and Heart-Health Connected?
The heart-gut axis refers to the close connection between the heart and the gut. It is well known that the gut and the heart are connected by the vagus nerve, which plays a crucial role in the communication between the two organs. However, recent research has suggested that the connection between the heart and the gut goes beyond this physical link.
Heart disease is the build-up of harmful plaque in the heart’s arteries that could lead to heart attack, heart failure, or death. In Canada, heart disease is the 2nd leading cause of death . According to the 2017-2018 data, about 1 in 12 (or 2.6 million) Canadian adults age 20 and over live with diagnosed heart disease .
Studies have shown that the gut microbiome (the collection of bacteria and other microorganisms that live in the gut) can influence the heart’s health. Research has shown that people with a high diversity of bacteria in their gut microbiome have a lower risk of heart disease . Not only do your gut microbes play a role in cardiovascular health, but so do the metabolites they produce.
The gut microbiome plays a role in the production of TMAO. Trimethylamine N-oxide (TMAO) is a small metabolite linked to cardiovascular disease (CVD). TMAO is produced by certain species of gut bacteria when they break down compounds called choline, phosphatidylcholine, and carnitine, which are found in foods such as red meat, eggs, and dairy products. Studies have found that increased levels of TMAO are associated with an increased risk of CVD, including heart attack and stroke. [3,4]
To reduce TMAO levels, it is recommended to reduce the intake of foods high in choline, phosphatidylcholine, and carnitine and to maintain a healthy balance of gut bacteria through a healthy diet and lifestyle, as well as the use of probiotics and prebiotics.
Short-chain fatty acids (SCFAs) are microbial-derived metabolites produced by the fermentation of dietary fibres by gut bacteria. The main SCFAs are acetate, propionate, and butyrate. These compounds have been shown to have various health benefits, including improving heart health. Studies reveal that SCFAs lower cholesterol levels and may also have anti-inflammatory effects [5,6,7].
Overall, the heart-gut axis is an important area of research that is helping to deepen our understanding of the close relationship between the gut and the heart. By better understanding this connection, it may be possible to develop new approaches to treating heart disease and other conditions affecting the gut and the heart.
 Masenga, S. K., Hamooya, B., Hangoma, J., Hayumbu, V., Ertuglu, L. A., Ishimwe, J., … & Kirabo, A. (2022). Recent advances in modulation of cardiovascular diseases by the gut microbiota. Journal of Human Hypertension, 1-8.
 Zeisel SH, Warrier M. Trimethylamine N-oxide, the microbiome, and heart and kidney disease. Annu Rev Nutr. 2017;37:157–81.
 Falony G, Vieira-Silva S, Raes J. Microbiology meets big data: The case of gut microbiota-derived trimethylamine. Annu Rev Microbiol. 2015;69:305–21.
 De Preter V, Coopmans T, Rutgeerts P, Verbeke K. Influence of long-term administration of lactulose and saccharomyces boulardii on the colonic generation of phenolic compounds in healthy human subjects. J Am Coll Nutr. 2006;25:541–9.
 Mell B, et al. Evidence for a link between gut microbiota and hypertension in the Dahl rat. Physiol Genomics. 2015;47:187–97.
 Marques F.Z.et al. High-Fiber diet and acetate supplementation change the gut microbiota and prevent the development of hypertension and heart failure in hypertensive mice.Circulation. 2017; 135: 964-977