There is a revolution going on in understanding a new cause of heart disease and vegans, those following a plant based diet, are enjoying recognition for their superior health. The revolution is a new connection between our dietary choices and the chance we will get clogged arteries and the bacteria in the GI tract are playing a central role. What is the news?
In 2011 researchers at the Cleveland Clinic searched for new and novel predictors of heart disease. The standard “risk factors” for heart disease were described in the 1960s from the Framingham Heart Study and include smoking, elevated cholesterol, elevated blood pressure, diabetes mellitus, and a first degree relative with early heart disease. Not much has changed since then and it was time to search for further instigators of heart disease.
The researchers found 3 compounds, choline, betaine, and TMAO as suspicious new factors in heart disease. TMAO or tri-methyl amine oxide, was new on the scene and is produced from choline and betaine in our diet. Further study in animal and human models found that TMAO was produced from dietary choline and betaine and was the new factor causing heart disease. The researchers showed that TMAO increased the accumulation of cholesterol in the wall of arteries to begin plaque buildup. Further work has shown that TMAO also prevents cleaning up of cholesterol diseased arteries so it is a double whammy.
TMAO is produced from choline, usually phosphatidyl choline, which is concentrated in egg yolks. As soon as a typical research volunteer eats eggs the blood level of TMAO skyrockets up in the blood. While some dietary choline is necessary for health, the higher the blood level of TMAO the more advanced and severe heart disease was found in patients at the Cleveland Clinic. Subsequent research has shown that feeding l-carnitine to subjects, in the form of a steak, produces major rises in TMAO also. It is now understand that both choline, betaine, and l-carnitine in eggs, dairy and meat are converted by the bacteria of typical Americans to TMA and then our liver converts it to TMAO. Watch out arteries.
How do vegans figure in this story? Researchers recruited vegans and paid them to eat eggs or steak and measured TMAO blood levels. What happened? Nothing. Vegans have different bacteria in our GI tract than omnivores and apparently the enzyme that convert these food sources to TMA is absent or nearly so. Certainly the bacterial flora of the vegans, and the inability to produce TMAO, is a major advantage in terms of avoiding heart disease.
What is brand new in TMAO research? It is now known that TMAO causes scar tissue in kidneys and is both a marker of kidney damage and directly injures kidneys. Furthermore, elevated TMAO levels in congestive heart failure are now established and TMAO may scar the heart too. Avoiding eggs, dairy and meat may be wise in these conditions. Researchers are working on blocking TMAO. If you block the conversion from TMA to TMAO you may end up smelling “fishy” and that may be an unpopular. A new agent, DMB, found in balsamic vinegar and some wines, has just been shown in an animal model to block the production of TMA from bacteria in the gut. Whether this will be safe or effective in humans is unknown.
For now, avoiding dairy, eggs and meat is the wisest path to improve your health and avoid the chronic diseases including heart disease, cancer, adult diabetes, obesity and dementia. There is a brand new lab test for TMAO available and my heart prevention clinic is the first in Michigan to offer it. So far my patients have been normal but I have a lot of vegan patients! So when people ask you where do you get your protein, just ask them “Where do you get your TMAO”?