Trimethylamine oxide, or TMAO, a compound linked to eating fish, seafood, and a mostly vegetarian diet helps reduce heart disease symptoms related to hypertension. This animal research reported in the American Journal of Physiology reveals that low-dose TMAO treatment can reduce heart tissue thickening (cardiac fibrosis) and markers of heart failure in animal model of hypertension. Subject to validation of these conclusions in humans, this is a whole new reason to adhere to a Mediterranean-type diet.
Blood levels of TMAO increase significantly after eating certain foods including fish and vegetables. The liver produces TMAO from trimethylamine (TMA), a substance produced by gut bacteria. Until this study, the cause of the high levels of TMAO in the blood and the effects of the compound on the heart and circulatory system remained unclear. Until then, nutritionists thought that plasma TMAO levels increased rather with the consumption of red meat and eggs. However, this new research reveals “that a diet rich in fish and vegetarian type is associated with a significantly higher plasma TMAO level than diets rich in red meat and eggs, which are also associated with increased cardiovascular risks.
Researchers from the University of Warsaw and the Polish Academy of Sciences looked at the effects of TMAO in (genetic) model rats of high blood pressure (HTA). One group of hypertensive rats received low-dose TMAO supplements in drinking water, and another group received plain water. These 2 groups were compared with a group of control rats not presenting the same genetic predisposition and also receiving pure water. The TMAO dosage has been designed to multiply by 4 the blood levels of TMAO vs the levels naturally produced by the body. The rats received this supplementation for 12 weeks or 56 weeks and then were evaluated on the cardiac and renal levels.
A reduction in cardiac fibrosis without secondary circulatory effects: experience shows that:
- TMAO supplementation has no effect on the development of hypertension in spontaneously hypertensive rats;
- but the state of the animals having received the compound is more favourable, and in a durable manner, until after more than one year of treatment at a low dose;
- the 4- to 5-fold increase in plasma TMAO level did not exert negative effects on the circulatory system but was found to be associated with a significant reduction in cardiac fibrosis and heart failure in these spontaneously hypertensive rats.
The study provides the first evidence of the potential beneficial effect of a moderate increase in plasma TMAO on the hypertensive heart, and thus highlights an additional benefit of following a Mediterranean diet rich in fish and vegetables.
