Lean Beef in a Mediterranean Diet May improve Gut Health and Reduce TMAO Levels
New clinical trial evidence suggests that replacing an american-style diet with a Mediterranean eating pattern, while still consuming lean beef, can significantly reduce TMAO levels and enhance gut microbial diversity, highlighting the importance of overall diet quality over meat quantity.
Study: Effect of Varying Quantities of Lean Beef as Part of a Mediterranean‐Style Dietary Pattern on Gut Microbiota and Plasma, Fecal, and Urinary Metabolites: A Randomized Crossover Controlled Feeding Trial. Image credit: sea Wave/shutterstock.com
A study by researchers at Pennsylvania State University suggests that Mediterranean-style diets with moderate amounts of lean beef offer better metabolic and gut health benefits than an average American diet with similar amounts of beef. The study is published in the Journal of the American Heart Association.
How diet shapes TMAO
Excessive intake of red meat is known to increase the risk of cardiovascular disease, probably by elevating blood levels of trimethylamine N‐oxide (TMAO). This metabolite is produced during gut microbiota-mediated metabolism of animal foods and is associated with atherosclerotic plaque formation.
Although several studies have linked beef intake to increased TMAO production, emerging evidence from clinical trials suggests that the inclusion of lean, unprocessed meat in heart-healthy dietary patterns does not increase levels of conventional cardiovascular risk factors.
The Dietary Guidelines for Americans recommend intake of 737 grams of meats, poultry, and eggs per week for a 2000‐kcal diet. Clinical evidence on heart-healthy dietary patterns reveals that a Mediterranean-style (MED) diet with a higher intake of red meat (500 grams per week) increases blood levels of TMAO compared to a lower intake (200 grams per week).
Given the potential impact of red meat on cardiovascular health,researchers at the Pennsylvania State University,USA,conducted a randomized,controlled-feeding study to investigate the metabolic and gut health effects of MED diets with different amounts of lean beef,and compared the outcomes with an average American diet with a similar amount of beef.
Four-period crossover trial
The study included three MED diets with 14, 71, and 156 grams of lean meat consumed per day per 2000 kcal. The impact of these diets on gut microbiota composition and blood, urinary, and fecal levels of TMAO was compared with that of an average American diet, which included 71 grams of beef per day, equivalent to 2000 kcal.
A total of 30 healthy individuals participated in the study, who consumed each diet for four weeks with at least a one-week washout period. Analytical samples were collected from participants at baseline and at the end of each 4‐week diet period.
The authors noted that Greek yogurt was included in the MED diets, while conventional
Here’s a breakdown of the key findings from the provided text, focusing on how different diets impacted outcomes:
1.Gut microbiota Diversity:
* MED diets (14g & 71g lean beef): Significantly increased gut microbiota diversity compared to the American diet (71g beef).
* MED diet (156g lean beef): Did not significantly increase diversity compared to the American diet.
2.TMAO Levels (a marker for cardiovascular disease risk):
* MED diets (14g, 71g, & 156g lean beef): all resulted in reductions in both blood and urinary TMAO levels compared to the American diet. Specifically:
* 14g MED: 1.7-fold reduction in blood & urinary TMAO
* 71g MED: 2-fold reduction in blood & urinary TMAO
* 156g MED: 1.7-fold reduction in urinary TMAO
* Important note: The study found that the relationship between gut microbiota diversity and TMAO levels was only observed when participants were classified as high or low TMAO producers.
3. Carnitine Levels:
* MED diets: Led to higher blood levels of carnitine (a TMAO precursor) than the American diet.
* However: The authors emphasize this doesn’t mean the American diet is better at converting carnitine to TMAO.
4. Microbial Function vs. Diversity:
* Participants with consistently high TMAO levels also had higher gut microbiota diversity, suggesting that how the microbiota functions is more critically important than just how much diversity there is.
* The study didn’t find diet-related shifts in predicted microbial functional pathways, suggesting that current predictive analysis methods may not be sufficient to capture true functional changes.
Overall Conclusion:
The study suggests that incorporating moderate amounts of lean beef (up to 156g/day) into a Mediterranean-style diet does not negatively impact TMAO levels and can even improve gut microbiota diversity in healthy adults. The Mediterranean diet‘s rich plant-based foods and fiber appear to play a key role in mitigating any potential TMAO production.
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