#6. Carnivore diet and gut health
The carnivore diet could damage the colon and degrade gut health. In fact, changes to the microbiome eating nothing but meat could colonize the gut with bacteria that increase the risk for heart disease. Animal protein is high in L-Carnitine, a type of amino acid.
The New England Journal of Medicine has published a
study which demonstrates certain strains of bacteria turn carnitine, as well as choline in eggs, into
TMAO, a compound that has been shown to damage the arteries. Not everyone who eats meat will have high TMAO levels, however, an unhealthy microbiome combined with a constant supply of red meat at every meal,could result in the perfect storm for TMAO to get out of hand.
There are many sound reasons to eat fiber, with one of the most important being the impact fiber rich foods can have on the microbiome. When we eat complex carbohydrates like yams, broccoli, rolled oats,
apples, and other plant foods, the plant matter ferments in the colon, which is a good thing. It’s the fermentation process that generates short chain fatty acids, like butyrate, which lines and protects the gut wall while also providing the body energy. By removing all fiber from the diet and eating only meat, you increase the likelihood two things will happen:
- Your microbial diversity will suffer and;
- Some of that flesh will putrefy in the gut which can break down the gut wall and increase the risk for cancer of the colon in the future.
Don’t believe the science?
The study above from Texas A&M, was designed to push back on the link between red meat and colon cancer, but their reason for doing so was that plant foods consumed with meat are protective.
There is also a
meta-analysis examining the link between colon cancer and red meat consumption. The evidence shows an increased risk for colon cancer and none of these studies look at a diet that is exclusively composed of red meat. The carnivore diet is potentially bad for the microbiome, increases the risk of intestinal permeability, and may increase colon cancer risk.
The mechanism seems to be undigested meat, which then ferments in the colon, leading to increased ammonia production and strains of bacteria that produce histamine.
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This
NPR Article does a nice job summarizing the findings of a
study that appeared in the Journal
Nature. The study looked at the short term impact on the microbiome of a meat heavy diet vs. a diet that included much more plant fiber. The meat heavy diet was very similar to the carnivore diet and it altered the microbiome for the worse in just two days. In particular, bacterial species that feed on bile, called
Bilophila, started to colonize the guts of the group following carnivore diet protocol.
Bilophila bacteria, like
Candida, aren’t necessarily “bad.” However, when they take over the gut as they are prone to do on extreme diets, that’s where problems can begin. Studies have linked
Bilophila to colitis in mice.
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See also:
Can undigested protein contribute to leaky gut?