Oddbean

There is no marker of gut bacteria health. We know next to nothing about the gut microbiome. For example, the fact that they influence the brain is a relatively recent discovery and hasn't even fully penetrated the establishment. That being said, my guess is that the gut reacts the best to fatty meat. The bacteria break down almost all the nutrients they require to short chain fatty acids anyway. Also, regarding the uric acid (urate actually) and kidney stones. 75% of kidney stones are calcium oxalate, so urate stones are a minority of stones. It has been common knowledge in medicine for decades now that blood urate levels correlate to urate stone and gout incidence, but no causal link has been established (i.e. a person with very high urate levels might never form urate stones or develop gout). It is why alopurinol, a drug that lowers urate levels, should never be prescribed for lowering urate levels in people who never had gout or urate stones. What is necessary for urate crystals to form in the body is inflammation. So, even though red meat increases urate levels a bit, it is not itself inflammatory. This is why carnivores usually report a drastic improvement of gout symptoms when adhering to a strict red meat diet. What else increases urate levels? Fructose is exclusively metabolized in the liver, which produces urate. Since sugary processed foods, which are also rich in seed oils, are also highly inflammatory, you get the golden recipe for gout and urate kidney stones. The metabolization of alcohol also produces urate and inflammation, so people who have gout issues should cease all alcohol and junk food consumption. Instead of saying that, however, most of my ignorant colleagues recommend reducing red meat consumption, which is contraindicated for humans.