December 11, 2018
Individuals whose diets consist of regular red meat consumption have triple the amount oftrimethylamine N-oxide (TMAO) levels than individuals who follow a plant-based or white meat diet, according to a new study. In turn, individuals who consume a red meat diet are at a greater risk for cardiovascular disease.
To reach this conclusion, the researchers recruited 113 healthy adults to follow a 2-week baseline diet that mirrored a typical American diet (carbohydrate 49%, protein 14%, and fat 37%). The participants were then randomly assigned to either a high-saturated-fat or low-saturated-fat diet arm.
Within each arm, the participants were assigned to 1 of 3 experimental diets (red meat, white meat, or non-meat) in random order for 4 weeks. Each diet type was separated by a 2- to 7-week washout period, during which the participants followed their regular diet.
The researchers collected both fasting plasma and urine samples on 2 separate days in the last week of each dietary intervention.
The findings showed that a chronic diet of red meat, but not of white meat or non-meat, more than doubled both plasma and urine TMAO levels.
Further, chronic dietary red meat increases systemic TMAO levels by enhancing dietary precursors, increasing microbial trimethylamine/TMAO production from carnitine (but not choline), and significantly reducing renal TMAO excretion.
However, once a participant stopped the red meat diet, TMAO plasma levels reduced within 4 weeks.
“According to the meta-analysis, the increases in plasma TMAO observed with the red meat diet would correspond to an approximate 4.5% increase in relative risk of mortality compared with the non-meat diet, and a 4.3% difference in mortality compared with white meat diet,” the researchers concluded.
Wang Z, Bergeron N, Levison BS, et al. Impact of chronic dietary red meat, white meat, or non-meat protein on trimethylamine N-oxide metabolism and renal excretion in healthy men and women [published online December 10, 2018]. Eur Heart J. https://doi.org/10.1093/eurheartj/ehy799.
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