Each of us has a unique combination of microbes in our gastrointestinal tract.
The study of gut microbiota — the trillions of bacteria and microbes that live in the human digestive tract — is a fairly new area of nutrition research. More and more evidence indicates that these tiny microbes have a powerful impact on our health, so understanding just how these organisms interact in our bodies and with the food we eat has become an important new field of study.
Each of us has a unique combination of microbes in our gastrointestinal tract. The mix can be altered by the foods we eat, medicines we take and many other factors. Some people have a specific gut bacterium that produces a compound called TMA (trimethylamine). TMA is then converted to TMAO (trimethylamine N-oxide) in the liver. TMAO has been in the spotlight recently as a factor for increased risk of heart disease and stroke.
Dr. Stanley Hazen of the Cleveland Clinic has been researching the effects of TMAO on heart disease for several years. He has found that people who have more TMAO in their blood also have a higher risk of heart disease and of dying earlier. From his studies, it appears that TMAO may make the blood more likely to clot and accelerate the rate of atherosclerosis. This occurs even if cholesterol levels are in normal ranges.
TMA, and thus TMAO, is synthesized by the gut bacteria from metabolizing choline, lecithin and carnitine. These compounds are commonly found in animal products, specifically red meat, deep-water fish, eggs and full-fat dairy, as well as in our body’s own bile acids. Chronic red meat consumption enhances the production of TMAO by the gut bacteria and reduces the kidneys effectiveness in expelling it. People who follow a vegetarian or vegan diet appear to have the lowest levels of TMAO.
Although much more research of TMAO is needed to determine if this is truly a major factor in heart disease risk, it is a worrisome development. There is a blood test available to test for TMAO; however, because this is a newly identified risk factor, the reference values still need to be established. For now at least, just knowing your TMAO number likely won’t benefit you.
There are steps, however, that you can take right now to hedge your bets against TMAO.
Minimize your use of full-fat dairy.
Decrease the amount of red meat, both processed and unprocessed, that you eat. How much is too much as far as TMAO? There is no good answer. But for general heart health and cancer prevention, the recommendations of no more than18 ounces of lean red meat per week and seldom eating any processed meat seems reasonable. Red meat is any meat that comes from a mammal, which includes beef, pork, lamb and venison.
Increase the plants in your diet. Plants are plentiful in fibers that help remove cholesterol from the body. They also have antioxidants, phytochemicals and probiotics that help support a healthy gut microbiome. Try adding meatless meals a couple of times a week. It’s recommended that we eat five to nine servings of fruits and vegetables every day.
Eat some foods rich in probiotics or live bacteria cultures, such as yogurt, kefir or buttermilk.
Try adding some fermented foods to your diet, such as sauerkraut, kimchi, kombucha or sourdough.
Limit egg yolks to no more than two per day, or one per day if you have a cardiac history.
Avoid nutritional supplements and energy drinks that contain choline, phosphatidylcholine, lecithin or L-carnitine.
Don’t overuse antibiotics. They can destroy your healthy gut microbes.
Anita Marlay, R.D., L.D., is a dietitian in the Cardiopulmonary Rehab department at Lake Regional Health System in Osage Beach.