High-protein, low-carb diets are kind of having a moment right now, so it probably comes as no surprise that I get questions like this quite often. Let’s take a trip inside my mind—here’s the lowdown on the carnivore diet and your gut. So if this is true, then it’s important to know what determines a healthy gut. Thankfully, there’s an answer from Rob Knight, M.D., and The American Gut Project. This groundbreaking 2018 study involved more than 15,000 microbiome samples from more than 11,000 human participants across 45 countries. It is by far the largest database connecting the gut microbiome to diet and lifestyle and therefore the best tool for understanding these connections. Here’s what Knight and researchers discovered when they analyzed their database to determine the clear-cut, most powerful determinant of a healthy gut microbiome: the diversity of plants in your diet. This was more important than age, gender, nation of origin, and even recent antibiotic exposure. And wait, there’s more: When we’re talking gut microbes, there is one nutrient more essential than the rest, and that is fiber. Prebiotic fiber is food for your gut microbes. When they feast on it, they release postbiotic short-chain fatty acids (SCFAs) that have healing effects throughout the body. They strengthen the good gut microbes and weaken the inflammatory bad ones. They also close the holes in the colon that are often referred to as “leaky gut,” optimize the immune system, lower cholesterol, and regulate blood sugar. Not to mention that SCFAs protect humans from killers like heart disease, stroke, and cancer and even cross the blood-brain barrier to improve brain function. In short, they are powerful! But there’s only one way to get SCFAs, and that’s through prebiotic fiber. And there is only one place you can get fiber from—plants! Yes, plants have cornered the market on fiber and SCFAs. There are some out there who may claim that you can find butyrate—one of the SCFAs—in high-fat dairy (like butter)2 or in a supplement. But just to set the record straight, ingested butyrate is not the same as butyrate produced by our microbes. When you eat your butyrate, it’s absorbed almost immediately in the small intestine without ever reaching the large intestine where you need it. This is why I stress the importance of fiber for SCFAs. There is no evidence that butter or a supplement is able to adequately recreate these benefits. If you’ve been paying attention, then you know there’s a problem here. I just told you that high-quality research from one of the leading scientists on the planet has shown us that the most powerful predictor of gut health is the diversity of the plants in our diet. In this regard, the carnivore diet is one-size-fits-all, and it’s not a size you want. You literally could not have less plant-based diversity than the carnivore diet. Plant diversity = ZERO. There was also that part about the healing benefits of prebiotic fiber, how it fuels the good gut microbes by producing SCFAs and has benefits throughout the entire body, including the brain. It’s an essential nutrient for a healthy gut. But again, we have a problem. Plants have a monopoly on fiber. It doesn’t exist in meat, eggs, or dairy—the constituent parts of a carnivore diet. In other words, you could not have less fiber in your diet than you will have on the carnivore diet. So, if you believe that fiber is critical to gut health—as I do—then you could venture a guess as to how good the carnivore diet is for gut health. Which brings us right back to the original question (see what I did there?): “I heard the carnivore diet is good for your gut. Do you recommend it?” It would seem the answer is pretty clear. But in case you need me to spell it out, that’s a hard “no.”
