Hypothesis and Emerging Research
What’s the Pegan Diet?
What’s the Pegan Diet?
If you ask functional medicine physician Mark Hyman, MD, what issues he’s most concerned about in our food systems, he’ll ask if you’ve got a couple of days. He might start by telling you about chronic disease and how it’s driven by corporate food manufacturers. He’ll spell out how poor and minority populations bear the brunt of food-based disease burden. When he gets to the climate and ecological consequences of our factory farming systems, he can rattle off a list so long you’ll become unsure where (or if) it’ll end. And while Hyman cites bad food practices as the root cause of each of these issues, he identifies better ones as what might save us on all fronts. That is: He’s hopeful.
While a stronger, healthier, more climate-conscious food system will ultimately rely on government intervention and corporate cooperation, Hyman believes the movement for better food starts with each of us. In his brilliant new book, The Pegan Diet, he advocates for a personalized common-sense approach to food and eating. It takes the best of what certain dogmatic diets—namely paleo and vegan—have to offer, reconciles their differences, removes the dogma, and, from there, helps us make the best decisions for our own bodies.
PS: You can watch one of our own staffers experience a week of the pegan approach on the fourth episode of our Netflix series, The goop Lab: “The Health-Span Plan.” (Spoiler: She was into it.) We made a “pegan” T-shirt, too.
A Q&A with Mark
The biggest problem right now is that the majority of our diet in America, and increasingly around the world, is ultraprocessed industrial food that is grown in ways that destroy the environment, the climate, and our health. It’s a pattern that’s leading to catastrophic consequences for humanity and the planet.
Six out of ten Americans have a chronic illness—heart disease, diabetes, cancer, dementia, you name it—related to our ultraprocessed diet. About 88 percent of us are metabolically unhealthy, meaning nearly nine out of ten of us are somewhere on the diabetic spectrum. The economic burden of that is staggering: One out of every five dollars in our entire economy goes toward health care. And 80 percent of that is spent treating chronic disease that’s almost entirely triggered by food.
Our industrial food system is also at the root of many social and health inequities. It disproportionately targets poor and minority communities, strapping them with countless consequences, from widespread chronic health problems to threatening future economic competitiveness. (For example: Diets based in processed foods hinder children’s ability to focus, learn, and perform academically.)
The ecological consequences are catastrophic. We’ve depleted our fresh water resources, damaged our aquatic and terrestrial ecosystems, and wiped out species of pollinators, livestock, and edible plants in favor of growing massive swaths of corn, wheat, and soy. Our food system, end to end, is the number one cause of climate change, driving about 50 percent of all climate consequences; that includes the effects of deforestation, factory farming and animal agriculture, soil loss, transportation, storage, refrigeration, food waste, and more.
What I see emerging is the beginning of a consensus on the question “What are the foundational principles of good eating?” While there is plenty of controversy around the margins, there’s a lot of agreement down the middle.
Here’s what most of us agree on:
•We should all be eating whole foods.
•We should all be eating lots of plants, especially those rich in phytochemicals.
•We should all be including healthy fats, nuts, and seeds.
•We should be eating foods that don’t spike our blood sugar.
•If we are eating animal foods, they should ideally be produced in humane ways that restore the environment and produce better-quality, nutrient-dense protein.
While there is some part of this framework that depends on education so that people can make the best choices for themselves and their families, the biggest impacts are made through expanded availability of and access to fresh, whole foods.
If we continue to grow food the way we grow it, we won’t be able to grow that food for much longer. We’ll run out of fertile soil. Climate change will destroy entire harvests. Being the smartest animals on the planet doesn’t save us from the threat of extinction if we’re not smart enough to plan ahead. This will ultimately take cooperation and government regulation: The Biden administration has expressed support for regenerative and organic agriculture, although we don’t yet have detail on Biden’s specific plan.
I was sitting on a panel once with a friend of mine, who’s a vegan cardiologist, as well as a doctor who was paleo. They were arguing over the benefits of the diets they followed, and I, in the middle of this ping-pong between them, jokingly said that if you’re paleo and you’re vegan, I must be pegan.
I realized that there were a lot of similarities between these two diets they were arguing about. In fact, everything was exactly the same except where you get your protein: animal food or beans and greens. They both eschewed dairy, recommended more fruits and vegetables, and encouraged good fats, nuts, and seeds. And yet they were divided by these ideologies. In order to best help people maintain their health, we have to reach beyond the ideologies and help people focus on two key principles that are now the foundation of the pegan diet.
The key principles of the pegan diet:
1. Food is medicine
Food is not just energy: It’s a set of instructions for your body that can change your biology. It affects your microbiome, your immune system, your detoxification system, your hormones, your brain chemistry. (You are what you eat, literally.)
When you’re choosing food, you should ask: Is this going to enhance or degrade my health? Consider what foods are the richest in nutrients, phytochemicals, plant medicines, and beneficial compounds that help restore health. It’s not simply the absence of ultraprocessed stuff. It’s more about what you add than what you take away.
Some people thrive on a vegan diet. Others do not. So while you might want to be a vegan, your body might not like it. You might become protein deficient, or you might become vitamin B12 or vitamin D deficient. You might experience muscle loss. You might develop a low sex drive or problems with fertility. It’s not that veganism is a poor way of eating; it’s just that it might not suit your unique needs. The same goes for paleo or keto or any other food philosophy. Listen to your biology, not ideology.
We estimate that there are at least 25,000 plant compounds in our food. Conventional databases track only about 150. Many more are just being discovered and cataloged. In fact, the Rockefeller Foundation is funding a Periodic Table of Food initiative that hopes to lead to a greater understanding of how these other compounds, called phytochemicals, work in our bodies and how to help the most beneficial ones become more widespread in our foods and in our diet.
Phytochemicals all have different properties, and different ones will affect different systems of the body in different ways. Let me describe one example.
Polyphenols and the gut microbiome: One of the bacteria in your gut microbiome, Akkermansia muciniphila, provides a mucus coating on the lining of your gut that helps protect you from food, particles, and bacteria that might otherwise enter your bloodstream and create inflammation for your body. It’s one natural line of protection against diabetes, obesity, autoimmune diseases, cancer, and heart disease. Many people have low Akkermansia, including those who have taken several courses of antibiotics. And it turns out that out if you have particularly low Akkermansia and you get cancer, you are significantly less likely respond to one of our most powerful treatments for cancer: immune checkpoint inhibitors. But the consumption of certain plant polyphenols, including those from cranberries and Concord grapes, has been shown to get Akkermansia to grow in the gut. One study in mice showed that introducing Akkermansia to the gut directly improved responses to immune checkpoint inhibitors.
That’s just one example of how a particular microbe in your gut responds to specific phytochemicals, and how that microbe can then grow and help you address chronic illness, even in how we treat cancer. Other phytochemicals affect other systems of the body. I could give you similar explanations of how some other compound affects your detox system, or how another affects your hormones, or countless other relationships between plants and our bodies. If we dismiss phytochemicals as unimportant because they’re not central vitamins and minerals, we’ll be ignoring compounds that potentially have powerful benefits for our health.
The idea of eating your meat as medicine is clearly provocative and controversial, but the idea arose from my understanding of the difference between feedlot meat and regeneratively grown or wild meat.
Most of the research that’s been done on meat has been on feedlot-raised, factory-farmed meat. This meat is produced by packing animals into tight spaces and feeding them mostly corn and soy. These conditions are widely accepted as not good for animals or the planet, and it’s been found that this meat is largely inflammatory in the human body, contributing to many kinds of chronic inflammatory diseases, including cardiovascular disease and cancer.
What’s coming up in the research more and more is that things look different with grass-fed animals or wild animals. These animals are raised foraging on hundreds of plants that all have different nutrients and compounds. Those compounds get taken up into the blood and meat of these animals. And it turns out that in addition to overall better protein and fat profiles in wild and regenerative meat, there are also all these additional phytochemicals, antioxidants, and nutrients.
Two pieces of steak could have the same gram-for-gram breakdown of protein, fat, and carbohydrates, and still these differently raised meats could have wildly different effects on the body depending on the quality and the composition of that meat.
Yes. We see similar patterns in dairy as we do with meat. Most of the dairy we eat today comes from Holstein cows bred to produce lots of milk that is rich in A1 casein, a milk protein that tends to cause inflammation and digestive issues in many people. We also pump those cows with hormones to keep them producing milk, which can have hormonal effects in the people drinking that milk. Even organic milk may be an issue for some people if it comes from one of these Holstein cows.
I prefer milk from sheep and goats, which are more often raised on grass. Sheep’s and goat’s milks are also a better fit for those who are lactose intolerant.
Mark Hyman, MD, is a practicing family physician and a leader, speaker, educator, and advocate in the field of functional medicine. He is the founder and director of The UltraWellness Center, the head of strategy and innovation of the Cleveland Clinic Center for Functional Medicine, and board president for clinical affairs for The Institute for Functional Medicine. He is the host of the health podcast The Doctor’s Farmacy as well as the fourteen-time New York Times–bestselling author of Food: What the Heck Should I Eat?, The Blood Sugar Solution 10-Day Detox Diet, and most recently, The Pegan Diet.
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