- Diets high in red and processed meats have been linked to an increased risk of heart disease and stroke, possibly due to specific gut bacteria that convert a dietary nutrient known as carnitine into a harmful chemical: TMAO.
- The Mediterranean diet, rich in plant-based foods, reduces risks of heart disease and stroke according to scientific studies.
- The gut microbiome, which denotes the enormous collection of bacteria and other microbes that reside in our bodies, plays an essential role in our overall health, including cardiovascular health.
- Switching from a red meat-heavy diet to a plant-based diet was found to reduce the presence of a specific bacteria that converts carnitine into TMAO, providing a possible reason for the link between red meat consumption and heart disease and stroke.
- Blood tests can assess an individual’s TMAO levels which can be used provide more personalized dietary advice, such as recommending a reduction in red meat consumption for people with high TMAO levels.
Investigations across numerous years have perpetuated a link between diets excessive in red and processed meats and an escalated risk to heart disease and stroke. Nonetheless, these studies could neither implicate red meat as the culprit nor explain its mechanism—if it were indeed the cause of these health issues.
The recent research findings shed light on why this could be the case. The crux of the matter appears to be specific gut bacteria, found to be more abundant in those who regularly consume red meat. Crucially, these bacteria convert a dietary nutrient known as carnitine into a harmful chemical: TMAO, which accelerates blood clotting and the blockage of arteries.
The Role of a Balanced Diet
Dr. Stanley Hazen, study co-author and the director of Cleveland Clinic’s Center for Microbiome and Human Health, suggests that the new information bolsters the prevailing knowledge regarding heart-healthy eating. He emphasizes the established Mediterranean diet, rich in fish, fruits, vegetables, legumes, olive oil, and nuts and low in red meat and processed foods. Clinical trials have demonstrated that this dietary regimen reduces risks of heart disease and stroke.
Significance of Gut Microbiome
“Microbiome” denotes the enormous collection of bacteria and other microbes that naturally reside in our bodies, primarily within the gut. The past few years have shed light on the essential role these gut microbes play—not only in digestion but also in immune system defenses, brain operations, and cardiovascular system health.
Dr. Hazen underlines the established fact that an increased risk of heart disease and stroke correlates with red meat heavy diets.
Historically, the usual suspect was saturated fat, abundant in animal products, as it can escalate “bad” LDL cholesterol which contributes to cardiovascular disease. However, according to Dr. Hazen, the negative impacts of saturated fat are insufficient to account for the excess heart disease risks associated with consuming massive amounts of red meat, indicating the existence of other factors.
A New Culprit Emerges
The proceedings of the latest study direct our attention to such a possible factor, says Lauri Wright, chair of nutrition and dietetics at the University of North Florida.
Wright points out our still-evolving understanding of the gut microbiome. Generally, diets rich in vegetables, fruits, and high-fiber grains nurture beneficial gut microbes. “It still goes back to food”, says Wright.
Concurring with Wright, Dr. Hazen strongly advocates using diet to modify gut microbiome rather than introducing certain bacteria via probiotic supplements. He likens changing diet to altering the “soil” that nurtures gut microbes.
The recent findings build upon earlier research by Dr. Hazen and his colleagues, primarily factors affecting levels of TMAO, the chemical produced when gut bacteria breakdown carnitine, a nutrient remarkably abundant in red meat.
Prior studies led by the team suggest that TMAO potentially increases the risk of heart disease and stroke. Subsequent research discovered that adding red meat to a healthy diet for a brief period elevates blood levels of TMAO; levels return to normal upon replacing red meat with either white meat or vegetable proteins.
In both human and lab mice studies, the researchers identified a cluster of gut bacteria known as Emergencia timonensis responsible for converting carnitine into TMAO. Omnivores seem to harbour substantial amounts of these bacteria, whereas longtime vegetarians and vegans have very few.
Implementing experiments in mice revealed that introducing E. timonensis surged TMAO levels and the blood’s clotting propensity. Comparable results were found in humans where switching from a red meat-heavy diet to a non-meat protein source resulted in a noticeable reduction of the E. timonensis microbes in stool samples.
Available blood tests can assess an individual’s TMAO levels. Dr. Hazen suggests these tests could potentially provide healthcare providers with an opportunity to provide more personalized dietary advice—for instance, recommending a reduction in red meat consumption for people with high TMAO levels.
Fermented foods containing certain microbes, such as yogurt and kimchi, also contribute to a healthy gut, adds Wright. However, she further emphasizes that an overall balanced diet predominantly fosters a healthier gut.
The American Heart Association offers substantial counsel on heart-healthy eating.