How meat, gut bugs, and heart disease are connected
Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When people eat red meat, a substance called L-carnitine gets broken down by certain gut bacteria into a chemical called TMAO, which can cause heart disease. People who eat meat regularly have more of these bacteria and make more TMAO. Vegans and vegetarians don’t make much TMAO from L-carnitine.
Surprising Findings
Vegans barely produce TMAO from L-carnitine, even when given high doses.
Most people assume nutrients act the same in everyone, but this shows long-term diet fundamentally changes how your body responds to food.
Practical Takeaways
If you eat red meat regularly, consider reducing L-carnitine supplements and increasing fiber-rich plant foods to support a healthier gut microbiome.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When people eat red meat, a substance called L-carnitine gets broken down by certain gut bacteria into a chemical called TMAO, which can cause heart disease. People who eat meat regularly have more of these bacteria and make more TMAO. Vegans and vegetarians don’t make much TMAO from L-carnitine.
Surprising Findings
Vegans barely produce TMAO from L-carnitine, even when given high doses.
Most people assume nutrients act the same in everyone, but this shows long-term diet fundamentally changes how your body responds to food.
Practical Takeaways
If you eat red meat regularly, consider reducing L-carnitine supplements and increasing fiber-rich plant foods to support a healthier gut microbiome.
Publication
Journal
Nature medicine
Year
2013
Authors
Robert A. Koeth, Zeneng Wang, B. Levison, J. Buffa, Elin Org, Brendan T Sheehy, Earl B. Britt, Xiaoming Fu, Yuping Wu, Lin Li, Jonathan D. Smith, J. DiDonato, Jun Chen, Hongzhe Li, Gary Wu, James D. Lewis, M. Warrier, J. M. Brown, Ronald M. Krauss, W. Tang, Frederic D. Bushman, A. Lusis, S. L. Hazen
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Claims (5)
If you eat meat and take L-carnitine, your gut bacteria might turn it into a substance that could clog your arteries. But if you're vegan or vegetarian, your gut bugs don’t do this much, so you’re less likely to make that substance.
If someone has high levels of L-carnitine in their blood, they might be more likely to have heart problems — but only if they also have high levels of another substance called TMAO.
Giving mice a supplement called L-carnitine every day makes artery disease about twice as bad, but if you wipe out their gut bacteria with antibiotics, that effect goes away — meaning the gut bugs are behind the harm.
In mice, certain nutrients and a gut chemical they produce can slow down the body's ability to remove cholesterol — but only if the gut bacteria are active.
The kinds of gut bacteria you have, especially if you eat a lot of meat, might be linked to higher levels of a substance in your blood called TMAO, which could mean your diet over time helps shape which bacteria stick around.