The Optimal Human Diet?
The Controversial New Carnivore Diet is Rattling the Foundations of Dietary Doctrine
A recent documentary titled “The Game Changers” has once again ignited the perpetual debate about what we are supposed to eat. The well-funded documentary, produced by industry heavyweights James Cameron, Arnold Schwarzenegger, and Jackie Chan, asks what on-the-surface seems like a reasonable question: What is the “optimal” diet for human performance? The film crew follows elite Special Forces trainer and decorated UFC fighter, James Wilks, on his quest to answer this seemingly innocent question. Wilks travels a circuitous journey: from studying the diet of Roman gladiators all the way to a slew of contemporary studies. In the end, after citing a handful of elite vegan athletes, personal antidotes of eye-popping increases in his own strength and endurance, studies about the inflammatory molecules produced by meat consumption, studies of the en vogue microbiome and large-scale epidemiological studies, Wilks concludes that a diet composed of exclusively (or mostly) plants is what we, as humans, preform best on.
Once the doc dropped on Netflix the predictable scrum followed, with meat eaters from every side of the isle raising their forks in staunch protest. One such protester, the popular omnivore diet advocate, Chris Kresser, was invited on the Joe Rogan Podcast with the intent of “debunking” the claims made by Wilks in the documentary. After an almost 3-hour marathon of point-by-point debunking, Kresser had done his best to once-and-for-all bury the notion that a vegan diet is optimal for the vast majority of people. Kresser’s position: Meat and animal products are, in fact, good for us as part of a balanced diet.
Despite Kresser’s best effort, however, the dust up was just getting started. After Kresser’s debunking episode, in the spirit of fairness, Rogan offered to host a mano-a-mano debate between Wilks and Kresser. Wilks and Kresser agreed. From the gate Wilks came out swinging. Accusations were flung, credibility attacked, each one citing study after study to support their argument. In this end, and not surprisingly, it wasn’t clear who won the debate. And herein lies the rub: each side seemingly has ample data to back their argument up. The result is that any debate on the perfect diet tends to deteriorate into a confusing quagmire; with people, even the experts, galvanized with a religious like fervor; or worse, like the two political parties in this country, entirely unable to see the others sides point of view.
Yet, amidst the din two tiny stepping stones of common ground were found between Wilks and Kresser: first, the Standard American Diet is awful, and second, a new diet most have probably never heard of, called the Carnivore Diet, is a bad idea, too.
The carnivore diet leaves little room for misinterpretation. The basic tenet of the diet is shockingly simple: Eat animals.
Only animals.
Zero plants.
For someone on the carnivore diet a typical day might go like this: breakfast: 4 egg yolks, a few ounces of raw liver, half a pound of so of ground beef cooked with beef suet (fat), and a spoon full of salmon roe (eggs). Skip lunch. Dinner: a huge ribeye steak — meals that thumb-their-nose at every established dietary guideline. Indeed, the diet is so far to one extreme of the consensus guidelines that even the most open-minded dietitians bristle at the thought of people actually eating this way. In a 2018 article in The Atlantic, Jack Gilbert, the faculty director at the University of Chicago’s Microbiome Center and a professor of surgery, described the diet as “A terribly, terribly bad idea.”
The introduction of the carnivore diet for many dates back to the summer of 2018 and another Rogen podcast. Rogan’s guest was Canadian author and psychologist Jordan Peterson. Two hours and 40 minutes into their conversation Rogan asked him to talk about his curious diet. “I only eat beef, salt and water…and I never, ever cheat,” Peterson said. Peterson explained that it all started with his daughter, Mikhaila, who suffers from a particularly aggressive case of the autoimmune disease rheumatoid arthritis. The course of the disease had been relentless, affecting 40 joints, deteriorating her hip and ankle to the point they had to be replaced with artificial joints.
Jordon’s wife, Mikhaila’s mother, had always felt there was a dietary connection. When Mikhaila would eat oranges, for example, her symptoms would flare. And so, heeding the dietary clue, one by one, Mikhaila began to eliminated all the foods she suspected she was reacting to. In the end, she was only left with three things: beef, salt and water. “And then her symptoms began to drop, one by one…until she had no symptoms, zero,” said Peterson.
Mikhaila then urged her dad, who has suffered from severe depression and anxiety his entire life, to try the diet. It took a while to convince him, but once Petersen committed to the diet a strangely broad and seemingly unconnected list of problems began to resolve―including his crippling depression that he had had since childhood. Peterson gave an account of his improvements: I lost 50 lbs, better sleep, more energy, mental clarity, “I’m intellectually at my best, ” said Peterson, psoriasis cleared up, depression is gone, stronger, the floaters in his eyes went away, and his gingivitis (gum disease) that is purported to be irreversible, is gone. “It’s like, what the hell!?”
One expert thinks he knows why. His name is Paul Saladino. Saladino, an MD, has become the ambassador for the controversial diet. Saladino, too, became fascinated by the diet when he heard Jordan Peterson’s recount of his daughter’s dramatic recovery, and, for him, it connected his own dietary experimentation and the clinical observations that he had been documenting for years when his patients changed their diets. “My first thought was this is crazy. I think it’s most people’s thought, because we come up against so much conditioning when we’re talking about these types of diets and so much narrative connected with the idea that we’ve always been told that plants are so good for us. As I thought about it more and more, I thought, okay. This actually makes some sense.”
For Saladino, the rational for the carnivore diet starts with a theoretical, evolution-based argument. “Plants are not really on the earth to serve humans and they develop a lot of potentially toxic compounds to defend themselves from animals that are eating them,” says Saladino.
How our bodies process the compounds (polyphenols) in plants we are told are beneficial is telling. “Our body immediately recognizes them as foreign and detoxifies and then excretes them.” It’s Saladino’s contention that the compounds in plants that we have been beaten-over-the-head telling us that they are good for us; sulforaphane, resveratrol and curcumin, for example, are entirely incompatible with our uniquely human biochemistry. “This is like mac’s and PC’s, plant molecules don’t get used in human biochemistry,” says Saladino. “They are not our operating system; they don’t use the same language we are programed in.” His anthropological argument claims that plants, at best, served as a filler food that humans turned to in times of desperation. They were not our go-to food of choice. Given the choice between a freshly killed mammoth and a patch of berries or edible grass or some wild mushrooms, our ancestors would have chosen the former every time.
Notable biochemist, Bruce Ames, has spent a good portion of his career studying the compounds in plants and his research has revealed some surprising facts about the plants we eat: They contain a surprisingly rich array of natural pesticides, so many, in fact, that the natural pesticides contained within the plants we eat far eclipse the man-made ones that health-conscious people pay extra to avoid. In fact, 99.99% of the toxic pesticides that a person consumes daily are produced naturally by the plants themselves. Ames says we consume anywhere from 5000 to 10000 different natural pesticides per day, many of which have been shown to cause cancer in laboratory animals just as well as the man-made pesticides we fear. Ames says the levels of natural carcinogens in the vegetables we eat are commonly thousands of times higher than the levels of synthetic pesticides.
Yet, even so, Ames doesn’t not advocate avoiding plants. Like most, he is convinced there is a net benefit. But according to Saladino’s research and clinical experience, this isn’t the case. While the toxins in plants may not cause clinically recognizable symptoms in a healthy person who exercises, they are doing nothing beneficial and may even be causing sub-clinical harm. And in someone with an autoimmune condition, like Mikhaila Peterson, the effects of the toxic compounds are much more pronounced. “Once these toxins are removed from the diet of someone with autoimmunity, miraculously, they began to heal.”
Autoimmunity has confused, fascinated and frustrated doctors for centuries. So-much-so that the question of the very existence of autoimmune disease remained open until the 1960’s. The confusion dates back to a series of experiments preformed in the late 1800’s by the famous, Nobel Prize winning German immunologist, Paul Ehrlich. In his laboratory, Ehrlich injected animals with blood from another species causing the immune system to launch an attack on the foreign blood. Yet when he injected animals with similar blood; either their own blood or the blood from the same species, the animal’s immune systems never formed auto-antibodies, or in other words, self-attacking antibodies. By 1901, Ehrlich was convinced there was enough proof to establish a new biological rule, which he termed horror autotoxicus, translated literally to mean the horror of self-toxicity. Ehrlich’s term described his new biological dictum: The inborn aversion the body has to immunological self-destruction.
Perhaps no one wanted to question the axiom of someone as respected as Ehrlich; or perhaps no one wanted to accept the revolting idea the body was indeed capable of turning on itself, whatever it was, researchers and physicians seemed to ignore the mounting evidence for autoimmunity well into the 20th century. By the 1960’s, however, enough evidence had accumulated that the existence of autoimmune disease could no longer be denied.
Today, the burden from autoimmune disease is enormous. The N.I.H estimates more that 24 million American suffer from one of 80 known autoimmune diseases. The American Autoimmune Related Diseases Association (AARDA) thinks the NIH numbers don’t reflect the true burden because the N.I.H underestimates the number of diseases that are autoimmune in nature. The AARDA website lists more than 100 autoimmune diseases and claims that once accounted for, the number of afflicted Americans could rise as high as 50 million. One thing everyone agrees on, however, is that for many postulated reasons, (diet, antibiotics, toxins) the rate of westerners with autoimmunity is rising at a rapid clip.
Still today, the exact pathological events that lead to autoimmunity remain unknown, yet some tantalizing clues have recently emerged. Most of these clues point to the gut as “ground zero” for autoimmunity to develop. Researchers have found that the microbiomes of people with autoimmune disease are often different from the microbiomes of healthy people, a condition loosely defined as dysbiosis. Dysbiosis occurs when the tenuous harmony of the trillions of microorganisms living in our gut is somehow disturbed. Many researchers believe the upshot of dysbiosis is inflammation, which over time corrodes the integrity of the intestinal wall, rendering it permeable to all kinds of debris including bacteria, a condition commonly referred to as “leaky-gut.” Under this scenario, all hell can break loose. The immune system, just doing its job, attacks the plant toxins or even bacteria crossing the now porous intestinal wall into the blood stream, and if the sites (called antigens) on the plant toxins (gluten, for example) or bacterial membrane look like, or “mimic” the antigens within our own bodies, it sets in motion a cascade of events known as “cross-reactivity.” The end result of cross-reactivity is horror autotoxicus — the immune system fooled into attacking itself.
Given what we know about the autoimmunity it’s easy to speculate about the therapeutic effect Saladino commonly sees once patients with autoimmunity commits to a carnivore diet: Once all the toxic compounds stoking inflammation are removed and the intestinal wall is finally able to heal thus preventing cross-reactivity, the patients began to feel better.
Frustratingly, conventional medicine has few good treatments for autoimmunity―with most treatments just addressing symptoms―certainly nothing approaching a cure. As a consequence, many victims are left searching for anything that might alleviate the corrosive disease course. Not surprisingly, given the reach of Rogan’s podcast (190 million downloads per month), many of those suffering from an autoimmune condition themselves, or their loved ones, heard Jordan Peterson recount the story of his daughters dramatic, diet-driven remission from rheumatoid arthritis. The miraculously claims made by Peterson from his strange diet instantly captivated the public’s attention.
“The diet exploded in popularity shortly after,” recalls Saladino.
Exploded indeed. Social media groups dedicated to the diet popped up, YouTube videos, blogs; hundreds or perhaps even thousands of those suffering from a spectrum of autoimmune disease began experimenting with the carnivore diet and sharing their results online.
For those told that Peterson’s evidence is entirely anecdotal; those that have suffered for years or even decades with autoimmunity, the calculus was easy: there is little to lose―perhaps other than a slightly increased grocery bill―from trying the carnivore diet.
Although far from a controlled clinical trial, after reading through the online personal testimonies, even the most skeptical physician would be hard-pressed to dismiss the effects of the diet outright. Many recount years of gut-wrenching autoimmune symptoms that began to improve once they fully adapted to the carnivore diet. Although anecdotal, one is struck by the consistency of the accounts. “When I read people’s accounts of trying this diet, it’s almost universally positive,” noted Rogan.
Yet, beyond the eye-brow raising claims being made about the carnivore diet’s ability to invoke enduring remissions in some people with autoimmune issue, Saladino’s claims extend further. He makes the bold claim that by avoiding plants and adopting a well-thought-out carnivore diet, eating the animal from nose-to-tail, including organ meats, collagen from connective tissue, and suet (beef fat), in addition to muscle meat; and including other animal products like egg yolks, fish, or fish eggs, for example, provides humans with the exact nutrients, in the exact amounts and ratios, to optimize human physiology. In other words, the “optimal” human diet. “It’s how we are supposed to eat,” says Saladino. If this supposition is true, it would explain why someone like Jordan Peterson would experience a litany of non-autoimmune-related problems resolving, including his claim that he was “intellectually at my best,” and “stronger” on the diet. “I see it in my patients all the time,” says Saladino.
When defending the carnivore diet, Saladino notes, one issue seems to come up more than the others: fiber. What about it? A carnivore diet, by definition, is entirely devoid of fiber. “Fiber is a fairy tale,” says Saladino.
The notion that fiber is good for us goes back to an Irish physician named Denis Burkitt. After traveling to Africa, Burkitt noted that the Africans ate more fiber and had less diverticulosis. Burkitt then stitched the two observations together, making the bold claim that fiber was protective against diverticulosis in addition to a range of other gastroenterological diseases. His message was widely disseminated with his 1979 internationally best-selling book Don’t Forget Fibre in your Diet.
“Except that is not what we see in clinical studies at all. In fact, we see the opposite.” The studies Saladino refers to show that the people that eat the most fiber have the most diverticulosis, and vice versa. And with regard to cancer, Saladino says there is no evidence that fiber reduces your chances of developing colon cancer. “What we’re seeing here is quite contrary to what people have been told,” he says. Additionally, many studies show that the removal of fiber results in less constipation and bloating, two very ubiquitous complaints. And what about the microbiome? “No one really knows what a “good” microbiome is,” says Saladino. Indeed, for many who try the carnivore diet, the proof is in the pudding. One of the first things devotees of the diet seem to observe is improved digestion, with all the nagging problems of bloating, constipation and excessive gas resolving over time.
To be sure, to make the heretical claim that the carnivore diet is the optimal human diet is merely controversial is an understatement. Most dieticians vehemently oppose the diet, just like Wilks and Kresser do. Most of the opposition hinges on a single question: How does one explain the mountains of data suggesting plants have a positive effect on human health? For example, the so-called French Paradox that links the polyphenols in red wine to cardiovascular health; the numerous studies showing that compounds in green tea can ward off dementia and possible Alzheimer’s; the ability of cruciferous veggies to reduce inflammation and reduce cancer risk.
The answer may lie in a fascinating biological phenomenon called hormesis. Hormesis is a term that describes how biological organisms respond to stressors. At low-doses, stressors like exercise induce positive health effects. However, researchers have shown that the hormetic response is bi-phasic, meaning as the dose of a stressor increases the effect turns from positive to negative. For example, research has shown that couch-potatoes and high-mileage runners both tend to have shorter lifespans than moderate runners. The hormetic response explains why studies show that something like ethanol in moderate amounts can have a positive effect but in excessive amounts a negative effect. This effect holds true in experimental models, too. When low doses of ethanol are given to the nematode, C. elegans, the hormetic effect resulted in an eye-popping 50% increase in lifespan. The hormetic effect is so pervasive in biological systems that it even holds true to a stressor like radon gas, a radioactive gas that when breathed in breaks down into lead within our lungs. Nothing about radon gas sounds good, yet at low doses radon gas appears to reduce the risk of developing lung cancer. However, once a certain threshold is reached, it becomes toxic.
And here is where the nuance lies, and perhaps the source of conflicting data that seems to muddy the waters of every debate on the optimal human diet. Ames and others (Dr. Steven Gundry, The Plant Paradox) have clearly established that plants are rife with toxins, yet, perversely, due to the strange biological phenomenon of hormesis, certain doses of theses toxins may be beneficial to certain individuals.
Because of hormesis, it’s easy to imagine how the data Wilks cites supporting vegetable consumption comes to be. The majority of Americans, eating the standard American diet and exercising little, or not at all, would likely benefit from the hormetic response induced by eating the toxins found in vegetables.
Yet in others, those with autoimmunity or other conditions, (Saladino thinks many more common aliments could have autoimmune origins, even many psychiatric disorders including depression) plant toxins could possibly push these people past the tipping point where the hormetic curve turns negative.
Saladino, who treats a lot of people with autoimmunity and other conditions, often sees an astonishing clinical benefit simply by removing plants from their diet.
Perhaps the take home lesson is this: Due to the phenomenon of hormesis, plants could have a dual nature, they could be both good and bad, depending on context and the individual — leaving those who seek to find a once-size-fits-all, “optimal” human diet on a quixotic mission that is destine to fail.
But Saladino humbly disagrees that we have to concede that easily. He is convinced there is a way-of-living (diet and lifestyle) that optimizes human metabolism giving us peak mental and physical health. Saladino contends that a nose-to-tail carnivore diet is the optimal human diet. But it comes with a caveat: As long as those eating a carnivore diet are willing to seek the hormetic benefits that plants may provide from other sources, like exercise, for example. Saladino argues that when a person eats a carnivore diet and exercises regularly then all the inputs the body is receiving from food and hormetic stimuli are in perfect harmony with our “operating system” without the deleterious effects of plant toxins. In other words, all the good with none of the bad.
“There is still this pervasive notion that plants have unique compounds which are somehow valuable to humans in a singular way. I would argue that is not true. There are better ways to trigger hormesis than ingesting these toxic plant molecules,” says Saladino. “They may have a hormetic effect, but then they often do other things which are detrimental to our bodies because our bodies do not recognize them.”
It hard to dismiss his point outright. We seem to be saturated with media reports of studies touting the health benefits derived from ingesting the compounds in plants but rarely hear the negative studies. For example, sulforaphane, a sulfur-rich compound isolated from cruciferous vegetables like broccoli and cauliflower is lauded for its health benefits, yet can cause hypothyroidism in even small amounts. One would be hard-pressed to find negative articles about curcumin, the bright yellow compound isolated from turmeric, yet Saladino says that in over 120 randomized, placebo-controlled trials it has never shown a benefit. The molecule is “a fooler” he says. Studies in petri dishes lead people to believe it might have a benefit but these benefits just don’t extrapolate to the complexity of the body. Once curcumin is ingested, it is barely absorbed (1%) and the tiny fraction that is absorbed is recognized as foreign and immediately shunted through detoxification pathways and excreted. Worse, there are many lesser-known studies suggesting that the curcumin that is absorbed can have toxic effects. Saladino contends we are much better off avoiding these supplements, eating a carnivore diet, and triggering hormesis with the things that our ancestors did, things like sunlight, cold and heat exposure, and exercise.
The never-ending dietary debate comically separates humans from the rest of the animal kingdom. No other species on the planet is confronted by the question of what to eat. No wild species gets to choose a diet. For every species, except us, even the concept of a diet is an absurdity — vegan, vegetarian, paleo, Akins, (I hear keto is all-the-rage with giraffes right now.) It goes without saying that each wild species eats within the biological niche that millions of years of evolution has matched them to. Indeed, some of the evidence for Saladino’s anthropological argument in support of carnivorism might be right in front of our eyes. If one takes a quick visual survey across the animal kingdom virtually every wild species looks healthy — it’s impossible to find an obese lion or chimpanzee or deer in their natural habitat. Conversely, as species, we do seem curiously sickly: obesity, diabetes, depression, and autoimmunity are alarmingly becoming the norm. If Saladino is right, it may offer a singular explanation for our sorry state.
It’s ironic that the one feature that sets us apart from the animal kingdom, our big brains, may be entirely responsible for divorcing us from our “optimal” diet. Agricultural technology has continuously improved crop yields to cheaply feed humanity, providing us with year-round fruits and vegetables, processed seed oils, high fructose corn syrup, and cheap carbohydrates from grains that didn’t exist until very recently in evolutionary terms. We have constant access to the plant toxins that were at best seasonal in our distant past, or didn’t exist at all.
If anything can polarize people as much as politics it’s the debate on what to put in their mouths. To be sure, the carnivore diet is the new far-left (or far-right) candidate in the dietary spectrum. With experts already labeling it from “a terribly, terribly bad idea” to “the optimal human diet,” don’t expect a consensus anytime soon. But the good thing about a diet, as opposed to politics, is that it is democratized down to the level of the individual. Anyone of us, at any time, is free to try any diet of our choosing and see what happens.
