Carnivore Diet: What the Research Says

October 27, 2020

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carnivore diet science research Following up on last week’s big carnivore post, today I want to look at some of the main reasons people choose a carnivore diet in the first place.

There are those who just like meat a whole heckuva lot and don’t want to be bothered with vegetables, but I don’t think they represent the majority of the carnivore crowd. From what I can tell, most people come to the carnivore diet because they’re dealing with persistent health issues that aren’t being adequately resolved through conventional means. Maybe they’ve been trying something like Primal, paleo, or keto for a while, but there’s still room for improvement. Others are doing well but wish to see if they could achieve another level of awesomeness by doing something different or, dare I say, more extreme.

In these cases, carnivore is a sensible experiment for a number of reasons:

Carnivore diets combine the advantages of ketogenic and elimination diets, both of which are already popular for dealing with intractable health problems.

A nose-to-tail carnivorous diet is highly nutritious, providing bioavailable vitamins and minerals, plus plenty of protein, that the body needs.

If carnivore puts you in ketosis—and it almost certainly will—you get the anti-inflammatory benefits of ketones, plus mitochondrial biogenesis, increased fat-burning, appetite suppression, and more.

By removing potentially problematic plant foods, carnivore diets contain little or no:

FODMAPs
Oxalates
Lectins
Phytates
Glycoalkaloids
Salicylates

Carnivore lends itself to intermittent fasting and caloric restriction, both of which have noted health benefits.

You know I’m a fan of self-experimentation. Like any good scientist, you should start by educating yourself. In that spirit, today’s post is a roundup of available research. Use it as a jumping-off point for your own investigations if you are considering going carnivore. As always, I am not providing medical advice here. Please consult your doctors before using carnivore, or any diet, therapeutically.

What Does the Research Say?

Unfortunately, I can’t find any randomized controlled trials looking at carnivore for any health issue. There are a small number of published case studies, and Shawn Baker is currently trying to crowdfund some research. Otherwise, we have to rely on anecdotes and inferences from studies on other related diets (low-carb, high-protein, keto, low-FODMAP, and so on). Anecdotes are important, but they’ll never replace well-designed empirical studies. You can find confirmatory anecdotes supporting any of your beliefs if you find the right subreddit.

I pulled together the best of what I could find for today, but as you’ll see, we still have a lot to learn. The medical conditions included here are ones I’ve been asked about personally or that seem to be popular in carnivore forums. If you’d like me to address another in the future, drop me a comment below.

Carnivore Diets and Autoimmune Conditions

The carnivore diet has been launched into the public consciousness in large part thanks to people like Mikhaila Peterson, who credit carnivore with saving them from debilitating autoimmune illnesses. Using dietary interventions in this context is nothing new. There are more than 100 autoimmune conditions with different etiologies, triggers, and symptoms. What they usually have in common is gut dysbiosis and systemic inflammation. Removing pro-inflammatory, high-glycemic, insulinogenic foods is key to overcoming them.

Many folks are already using low-carb, ketogenic, or gluten-free diets to keep their symptoms at bay. The carnivore diet simply takes those a step further. But does it work? Anecdotally, yes, for some people anyway.

Does Carnivore Heal Leaky Gut?

Many doctors say that autoimmune issues “start in the gut,” since so many autoimmune conditions are characterized by increased intestinal permeability, commonly called leaky gut.¹ Two main causes of leaky gut are imbalanced gut microbiome—having too many bad microbes and/or not enough of the good guys—and harmful compounds in food, such as gluten.

Carnivore eliminates plant foods, which are the source of most of those harmful compounds, and it offers a hard reset for the microbiome. One study showed profound microbial changes in the gut after just a few days of shifting to carnivore.² Of course, different isn’t always better. I guarantee that an all-Oreo diet will produce some pretty profound changes, too, but I wouldn’t call them favorable.

In this case, though, we have some promising evidence from the Paleomedicina clinic in Hungary. They use a protocol they call the Paleolithic Ketogenic Diet (PKD), which starts out as full carnivore, though patients are ultimately allowed to include a small amount of approved, organic vegetables. Doctors administer a test called the PEG400 intestinal permeability test to all patients and claim great success in bringing patients into normal ranges with their protocol.³ However, the precise data is not published anywhere to my knowledge.

Carnivore for Arthritis

Mikhaila Peterson famously overcame debilitating rheumatoid arthritis with her all-meat diet. In his book The Carnivore Diet, carnivore drum-banger Shawn Baker claims that joint pain is frequently alleviated by carnivore, in his experience.

However, most research has focused on vegetarian diets. A few studies have demonstrated the benefits of a Mediterranean diet,⁴ and omega-3 supplementation⁵ for decreasing inflammation and pain among rheumatoid and psoriatic arthritis patients. One small, short-term study found no significant benefit of a ketogenic diet.⁶

A single report from The Medical Journal of Australia in 1964 reports the success of using a high-protein, gluten-free diet to successfully put 20 rheumatoid arthritis patients into remission for a period of up to 18 months.⁷ Check out the author’s commentary from the discussion:

“When man changed from food-gatherer (nomadic hunter) to food-producer, epochal changes in his ecology (to village community, urbanization and eventually to civilization) were paralleled by similar changes in his diet. The two or three millennia in prehistory during which the transition to agriculture took place is a relatively short period in the biological history of man. In terms of human evolution, this transition could be too sudden for the development of an adequate adaptive response to the drastic changes in his dietetic habits. The idea advanced here is that the challenge to man’s metabolism by the protein-complex of wheat (and rye) could lead to obscure syndromes;…”

Prescient indeed.

Hypothyroidism and the Carnivore Diet

Individuals with hypothyroidism, including autoimmune Hashimoto’s thyroiditis, frequently rely on dietary interventions like the autoimmune protocol (AIP), paleo, Primal, keto, and now carnivore. Despite abundant anecdotal evidence that they help, there have been few confirmatory studies to date.

Two recent papers confirm that AIP⁸ and a gluten-free diet⁹ are feasible and can reduce symptoms and improve quality of life for people with Hashimoto’s. The Paleomedicina team has also reported that they can successfully treat hypothyroidism with the PKD, but those data are not available in journal articles.

Carnivore Diet for Psoriasis

On the one hand, calorie-restricted¹⁰ ¹¹ and gluten-free¹² seem to help psoriasis sufferers. Higher intakes of omega-3 fatty acids do as well, which might be expected on a carnivore diet rich in small, oily fish like anchovies and sardines.¹³ ¹⁴ On the other hand, case studies going back decades suggest that high-protein and high-fat diets are not effective and in fact worsen psoriasis symptoms.¹⁵ ¹⁶ ¹⁷ A recent controlled study in mice found the same.¹⁸

This is one case where I’d tread cautiously. Of course, a quick Google search turns up plenty of people whose symptoms were improved after going carnivore. It can work, and there’s one case study of a patient who was helped by a low-carb, high-protein ketogenic diet.¹⁹ Still, I think it’s likely that some of those lucky folks experienced relief because they removed triggers like gluten, eggs, or dairy. They may not have needed to go full carnivore.

Carnivore Diet for IBS

If a carnivore diet can potentially reduce intestinal permeability, favorably shift the microbiome, and reduce systemic inflammation, it should help with gastrointestinal problems like IBS.

Clinicians often recommend low-fiber and low-residue diets for their IBS patients.²⁰ “Residue” is the undigested stuff in food—the leftovers, if you will—that passes through the gastrointestinal tract and gets excreted. Carnivore is an extremely low-residue and low-fiber diet.

Likewise, low-FODMAP diets show considerable promise for relieving the pain and other unpleasant symptoms of IBS.²¹ In studies, up to three-quarters of patients find relief.²² Remember, FODMAPs are fermentable short-chain carbohydrates that often cause gastrointestinal distress for people with existing GI dysfunction. You won’t find them on a carnivorous diet.

The Paleomedicina team also published a case study of an adolescent boy with Crohn’s disease—a severe form of IBS—who was able to go off his Crohn’s medication after just two weeks on the PKD. After ten months on the diet, ultrasounds of his intestines were normal, and there were no longer markers of intestinal permeability.²³

What about Using Carnivore to Treat Gastritis?

Gastritis is inflammation of the stomach lining. Generally, it’s treated with medications like antibiotics, proton pump inhibitors, or antacids, depending on what’s causing the inflammation. There’s very little research looking at dietary interventions to treat gastritis—in humans anyway. You’re in luck if you’re interested in cheetah or ferret gastritis, though.

If you have gastritis caused by H. pylori bacteria, I’d recommend you tackle that directly with the help of a medical practitioner. Otherwise, it’s certainly worth exploring what foods, if any, exacerbate your symptoms. Starting with a carnivore diet as a baseline and then reintroducing foods slowly is one way to do so.

Could a Carnivore Diet Ease Depression?

Converging evidence suggests a link between diet and depression, and a role for dietary modification in treating depression. First, it’s increasingly clear that there is a strong connection between gut health and depression, thanks to the gut-brain axis.²⁴ ²⁵ Many experts also consider systemic inflammation to be a root cause of depression.²⁶ Therefore, any diet that improves gut health and reduces inflammation is potentially useful.

Psychiatrist Dr. Georgia Ede has become an outspoken advocate of carnivore for depression, as well as other mental health disorders, on these grounds. She also correctly points out that the brain requires fat, including cholesterol, and other nutrients that are much more abundant in animal foods than in plant foods, such as choline, carnitine, omega-3 fatty acids EPA and DHA, and vitamin B12.²⁷

A 2015 review of dietary interventions for depression and anxiety found that they frequently include recommendations to reduce red meat intake, but that makes them less likely to be effective.²⁸ Likewise, one study found women who consume less red meat were at greater risk for major depression.²⁹

Carnivore Diet to Reverse Gum Disease?

You probably learned as a child that sugar is public enemy number one when it comes to dental health. In part, that’s because it disrupts the oral microbiome. That’s only part of the story, though. Gum health also goes hand-in-hand with gut health and systemic inflammation. That’s why gingivitis and periodontitis are common among diabetic folks—because of the hyperglycemia and chronic inflammation characteristic of poorly controlled diabetes.³⁰ ³¹

Carnivore advocate Jordan Peterson, Mikhaila’s father, claims to have reversed his own gum problems once he went all-meat. Some indirect evidence backs his experience:

In one small study, researchers replicated a Stone Age village and set up ten people to live there for four weeks. Despite having no access to toothbrushes or their handy waterpiks, their gum health increased.³²
A pilot study showed that when ten participants ate a low-carb (<130 grams per day), high-omega-3, nutrient-dense diet that sounds quite like a typical Primal diet, gum health significantly improved after just six weeks.³³ In a follow-up, participants experienced less gum bleeding after four weeks on the diet, and they also happened to lose weight.³⁴

Carnivore for weight loss

There’s every reason to suspect that carnivore diets should promote weight loss. If you’ve ever tried, you know it’s hard to overeat protein. Because protein is highly satiating, it tends to lead naturally to caloric restriction.³⁵ High-protein (not carnivore) diets are shown repeatedly in laboratory studies to be favorable for weight loss.³⁶ ³⁷ ³⁸ And of course, we know that ketogenic diets can be great for burning excess body fat.

Potential Negative Health Impacts of Carnivore?

Detractors will tell you that carnivore must be bad for your health, what with all that carcinogenic red meat and artery-clogging cholesterol (/sarcasm). Not surprisingly, I don’t put much stock in those arguments. Nevertheless, in the spirit of open-minded pursuit of truth, let’s see what the data actually say.

Carnivore Diet and Colon Cancer

I have already debunked the shoddy epidemiological studies that fuel the belief that red meat causes colon cancer, but it’s one of those conventional wisdom “truths” that won’t seem to go away. Sure, don’t eat a ton of processed meats, and don’t eat your red meat on a white-flour hamburger bun alongside fries cooked in rancid oil. But where’s the evidence that a proper nose-to-tail carnivore diet increases cancer risk?

I can’t find any, but I did find two case studies from the Paleomedicina team that are relevant to this question:

One of their patients with grade 1 colon cancer remained stable for almost seven years without conventional treatment thanks to strict adherence to the PKD. ³⁹ It’s not clear if the patient was carnivore over the entire period.
Another one of their patients used the PKD following a diagnosis of rectal cancer. His symptoms and cancer markers improved when he followed the diet religiously, but he was unable to do so long-term. ⁴⁰

Emerging research also suggests that ketogenic diets exert anti-tumor effects with certain colon cancers.⁴¹ ⁴² ⁴³ Quite the opposite of what the fearmongers would have you believe.

Will a Carnivore Diet Cause Gout?

Gout is a painful form of arthritis that occurs when urate crystals build up in joints. It can be triggered or exacerbated by foods and beverages that contain purines, which are metabolized into uric acid. Red meat and organ meats are primary sources of purines, so doctors often advise people to limit or eliminate them from their diets—despite consistent evidence that it actually helps.

As I’ve written before, prescribing low-meat diets for gout is a case of faulty logic. For one thing, meat is hardly the only dietary source of purines. Vegetarians and vegans also suffer from gout, and, according to one study, vegans have higher serum levels of uric acid.⁴⁴ On the flip side, people who follow a high(ish)-protein Atkins diet have lower serum uric acid levels.⁴⁵

We should be looking to sugar, especially fructose, and alcohol as more likely culprits, and addressing underlying metabolic syndrome and insulin resistance that make gout more likely. That said, if you already know that red meat and offal trigger your gout, there’s no reason to add more in the hopes that that will fix it.

Is a Carnivore Diet Bad for Women?

This is the same concern lobbied against keto, namely that any “restrictive” diet is dangerous for premenopausal women. There’s a kernel of truth here. Women’s bodies are more sensitive to calorie and nutrient insufficiencies during their reproductive years. All that means, though, is that they have to be especially mindful about getting enough nutritious food. This can be more difficult with diets like carnivore and keto, which tend to be highly satiating, but it can certainly be done.

For what it’s worth, some of the most outspoken carnivore advocates are women like Peterson and Amber O’Hearn who used a carnivore diet to completely turn their health around for the better.

General Advice and Cautions

In the absence of solid scientific evidence regarding the benefits or downsides of carnivore diets, what is a data-minded, health-conscious individual to do?

Follow the advice I’ve previously offered regarding eating nose-to-tail, including plenty of healthy fats, and supplementing as needed.

Stay flexible. As more data and new insights come along, be willing to adjust, even abandon, your approach if that seems wise. Never be afraid to pivot.

Consult your doctor about your specific situation. Ask if there are specific reasons a carnivore diet might be contraindicated for you.

Is There Anything Carnivore Can’t Do?

Definitely. It might well help a lot of people with a lot of different issues, but it’s not a panacea.

I’m also not convinced it’s wholly necessary for everyone who tries it. At the end of the day, the average person will benefit tremendously from any diet that gets them away from sugar and ultra-refined grain products, and toward a diet comprised of whole, natural foods. Primal, paleo, Mediterranean—these are probably sufficient for many folks. But then, desperate times may call for desperate measures.

As with any intervention, be it diet, lifestyle, pharmaceutical, or other, there will be some people for whom it works wonder and some for whom it works not at all. Carnivore is no different. Is it worth trying if you have a chronic issue that you believe may be diet-related? Absolutely, with your doctor’s knowledge, of course. Would I feel comfortable offering a 100 percent money-back guarantee? Nope.

The fact remains, all we have to go on right now are anecdotes and circumstantial evidence. These are powerful anecdotes to be sure, and ones that I have no reason to doubt. Still, I’m eager for well-controlled scientific studies, which unfortunately aren’t forthcoming. Until then, I’ll continue to support everyone in wise self-experimentation.

Tell me: if you’ve tried a carnivore diet, what was your experience?