Plant-based diet may help boost bacteria that protects heart health: Study

A new study found that a plant-based diet can result in a lower risk of coronary heart disease by influencing the gut microbiome pattern to favor good bacteria. 

In a study published in the Journal of the American College of Cardiology​, researchers report that reducing animal product intake and following a mostly plant-based diet can decrease your risk of heart disease by minimizing the adverse effects of a gut microbiome metabolite associated with increased risk of coronary heart disease.

Less TMAO, less risk 

For this study, scientists zeroed in on the metabolite trimethylamine N-oxide (TMAO). TMAO is produced when gut bacteria digests nutrients commonly found in animal products like red meat. The metabolite has been connected to increased heart attack and coronary heart disease (CHD) risk. Vegan or vegetarian diets have been found to reduce the levels of TMAO that the body produces.

Study details 

The research team examined 760 women in the Nurses' Health Study, a prospective cohort study of 121,701 female registered nurses aged 30 to 55 years old. Women reported data on their dietary patterns, smoking status and physical activity, as well as other demographic data. They also provided two blood samples taken at Cleveland Clinic, 10 years apart. 

Results 

Researchers found that women who developed coronary heart disease during that time period also had higher amounts of TMAO in their blood, as well as poorer diets, higher BMIs, and a family history of heart attack. The study suggests that participants who had the greatest increase in TMAO amounts during the study also had a 67% higher risk of developing coronary artery disease. 

"Diet is one of the most important modifiable risk factors to control TMAO levels in the body," ​said Lu Qi, MD, senior study author and director of the Tulane University Obesity Research Center. "No previous prospective cohort study has addressed whether long-term changes in TMAO are associated with CHD, and whether dietary intakes can modify these associations.”​

The study authors found no differences in TMAO levels between the CHD and control participants at the first blood sample collection. However, the second blood sample collection taken 10 years later found that TMAO levels were significantly higher the participants with CHD. Every increase in TMAO was associated with a 23% increase in CHD risk. This association remained after controlling for demographic, diet and lifestyle factors, confirming the link between higher TMAO levels and CHD risk.

The heart-gut axis 

"The findings of the study provide further evidence for the role of TMAO as a predictive biomarker for heart disease and strengthens the case for TMAO as a potential intervention target in heart disease prevention," ​said Paul A. Heidenreich, MD, MS, professor of medicine at the Stanford University School of Medicine. "The results should encourage us to continue to advocate for a more widespread adoption of healthy eating patterns."​

Qi concluded, “Our findings show that decreasing TMAO levels may contribute to reducing the risk of CHD, and suggest that gut-microbiomes may be new areas to explore in heart disease prevention.”​

Source: Journal of the American College of Cardiology​

Volume 75, Issue 7, 25 February 2020, https://doi.org/10.1016/j.jacc.2019.11.060​

“Long-Term Changes in Gut Microbial Metabolite Trimethylamine N-Oxide and Coronary Heart Disease Risk”​

Authors: Y. Heianza et al.