Led by Stanley Hazen, M.D., Ph.D., the research complements previous studies showing that trimethylamine N-oxide (TMAO) in the gut can lead to the development of cardiovascular disease,heart attacks, and strokes; high levels of TMAO in the blood are used to predict possible future heart problems and even death risks. TMAO is produced when gut bacteria digest choline, lecithin and carnitine – compounds found in animal products like red meat and liver.
In the latest study, 113 participants were given complete meal plans in which 25 percent of their daily calories came from either red meat, white meat, or non-meat protein sources.
After one month on the red meat diet, average TMAO levels increased three-fold, with some participants showing a significant increase of 1,000 percent compared to those on the non-meat diet. Similar increases were observed in the urine of the meat-eating group. When participants stopped sourcing their protein from red meat, their TMAO levels abated.
The study also found that consumption of red meat worsens kidney function, hindering its efficiency in expelling the TMAO compounds. Dr Hazen said in a statement, “This is the first study of our knowledge to show that the kidneys can change how effectively they expel different compounds depending on the diet that one eats – other than salts and water.”
He added, “We know lifestyle factors are critical for cardiovascular health, and these findings build upon our previous research on TMAO’s link with heart disease. They provide further evidence for how dietary interventions may be an effective treatment strategy to reduce TMAO levels and lower subsequent risk of heart disease.”
Another study by Dr Hazen and his team found that while meat-eaters rapidly create TMAO from carnitine, a nutrient found in red meat and some energy drinks and supplements, vegans and vegetarians showed limited ability to do so. Dr Hazen said that it is “remarkable that vegans and vegetarians can barely make TMAO from dietary carnitine.”