It takes time for new research to filter down to common knowledge.
Already 11 years have passed since Dr Stanley Hazen of the Lerner Research Institute discovered the close correlation between TMAO (trimethylamine-N-oxide) and increased risk of heart attack or stroke.
In 2013 the American Heart Association and the American Stroke Association described this study as one of the top 10 advances in heart disease and stroke science. Since then it has also been fingered in chronic kidney disease, cancer and even type-2 diabetes.
ALSO READ : Lifestyle Medicine: Modern diet not doing our brains any favours
So what is TMAO and how does it affect our health? This provides a good example of the interaction between the gut microflora and our body. Certain bacteria are responsible for breaking down L-carnitine (found in red meat) and lecithin (found in egg yolks, meats and full-fat dairy products).
But lecithin is also normally excreted by the liver into the intestines as a component of bile – so we all have the potential to produce elevated levels of TMAO. However in practice, elevated TMAO levels are directly related to dietary ingestion of L-carnitine, choline, betaine and lecithin – all mostly from animal products e.g. red meat, eggs, dairy, shellfish and salt-water fish. Specific bacteria produce TMA, which is then absorbed and transformed into TMAO in the liver.
Interestingly, people who eat mostly a plant-based diet have relatively few of the bacteria that produce TMA, and if they change their diet to incorporate animal products, it takes a few weeks before the bacterial spectrum changes to be able to make TMA.
People admitted to hospital with chest pain, who have high levels of TMAO, have a six times higher risk of dying of heart disease or stroke in the next six months. Peripheral vascular disease is also more common.
There is a direct causative effect of TMAO on atherosclerosis. Secondly, high levels of TMAO inhibit the body’s ability to get rid of LDL – the “bad” cholesterol. A large 2020 study including over 10,000 patients, showed elevated TMAO levels increased the risk of major adverse cardiovascular events by 58%. TMAO levels are not yet routinely checked in South Africa.
A 2017 study showed a strong correlation between high levels of TMAO and newly diagnosed diabetes type 2. In 2015, a study showed that higher levels of circulating TMAO were associated with worsened chronic kidney disease. Colo-rectal cancer is also associated with high levels of TMAO, and may even be a prognostic marker of future outcome.
Non-alcoholic fatty liver disease (NAFLD) is a major health concern around the world. Once again TMAO appears to influence the severity of NAFLD.
What is the take home message? Increasing the intake of whole plant foods, and greatly reducing the intake of animal products has important health enhancing benefits.
Dr David Glass
MBChB, FCOG(SA), DipIBLM.
HAVE YOUR SAY
Like the South Coast Herald’s Facebook page, follow us on Twitter and Instagram
