What Is The Pegan Diet?
Coined by Dr. Mark Hyman in 2015, the “Pegan” diet is a combination of the vegan and Paleo diets. At face value, a marriage of these two diets seems unlikely.
Whereas the vegan diet excludes all animal products, the Paleo diet includes plenty of meat and other animal products supposedly eaten by humans in the Paleolithic era.
So, how does Mark Hyman's Pegan diet combine elements from these two diet plans?
How To Follow The Pegan Diet
Drawing from the vegan camp, the “Pegans” follow a plant-based diet, with roughly 75% of calories coming from plant foods. However, the Pegan diet also incorporates certain principles of the Paleo diet. Namely, animal products are also permitted in the Pegan diet.
In addition, dairy products, gluten, and beans are heavily restricted. However, Dr. Hyman writes that meat should be consumed as a side dish or a condiment, as plants should be the star of every meal.
Summary: The Pegan diet is a mostly plant based diet, with only 1/4 of all calories coming from animal sources. Beans, whole grains and dairy products are limited or excluded as well.
Pros Of The Pegan Diet
1. Emphasis On Whole Plant Foods
One of the most impressive benefits of a plant-based diet is its ability to not only prevent, but reverse heart disease. Dr. Caldwell Esselstyn of the Cleveland Clinic demonstrated the power of lifestyle intervention in his 2014 study.
In his research, 198 patients with advanced cardiovascular disease volunteered to eat a completely plant based diet. Of the 177 patients who stuck with the plant based diet for over three years, 99.4% of them prevented and reversed their heart disease.
On the other hand, of the twenty-one patients who did not comply with the diet, thirteen of them suffered a major cardiac event such as a heart attack or stroke. This landmark study demonstrates that a plant based diet can reverse heart disease — no other diet has ever accomplished this feat (1).
Although the Pegan diet will not reverse heart disease, its emphasis on whole plant foods can still reduce our risk of developing it over time.
2. Improved Mental Health
While eating more plant foods can increase the quantity of days in our life, the quality of ours days is just as important. Our diet can have a profound effect on our mood and cognitive function on a daily basis.
In 2009, a team of researchers compiled 106 overweight and obese participants for a study. Then, they separated them into two groups: one group would consume a low fat diet and the other would consume a low carbohydrate diet. The low fat diet contained more plant foods than the low carb diet.
Yet, both groups ate the same amount of calories. After one year, researchers concluded that “there was a favorable effect of an energy-restricted low fat diet compared with a... low carb diet on mood state” (2).
Three years later, other researchers established a causal relationship between diet and mood. Participants were split into three groups: an omnivorous group, a pescatarian group, and a vegetarian group. After a two week trial, “several mood scores for vegetarian participants improved significantly” (3).
But how can we explain this positive change in mood? There is some evidence that arachidonic acid, an omega-6 fatty acid, may play a role. Found in animal foods such as chicken and eggs, arachidonic acid may increase inflammation in our brain, which can negatively impact our mental health (4).
When we replace animal foods with plant foods, we not only avoid consuming arachidonic acid, but we also take in more antioxidants, which can reduce inflammation in the body.
3. Avoidance Of Dairy
Increased Cancer Risk
Mark Hyman's Pegan diet prohibits the consumption of cow’s milk — and for good reason. Dairy consumption is strongly correlated with a variety of cancers. Across the world, dairy consumption is significantly associated with both testicular and prostate cancer in men (5).
While this graph is compelling, there are hundreds of possible variables that can affect the development of prostate cancer. This begs the question, what happens when we control for every variable?
In one experiment, researchers at Clemson University set up two petri dishes containing prostate cancer cells. On one petri dish, they introduced organic cow’s milk. On the other, almond milk. In a completely controlled environment, cow’s milk stimulated the growth of prostate cancer by over 30%. Yet, almond milk suppressed the growth of these cells by over 30% (6)!
Five researchers at cancer institutes in Korea carried out a similar experiment. This time, they introduced casein, the main protein found in cow’s milk, to the petri dish. Prostate cancer cells displayed a proliferation of roughly 200% after exposure to casein (7).
Whey protein, which is also derived from milk, produces a similar proliferation of prostate cancer cells in a petri dish (8).
However, we know that the human body is much more complex than a petri dish. As a result, researchers at the University of Yamanashi in Japan set out to determine if these petri dish findings were consistent with actual human data.
After conducting a meta-analysis of eleven scientific studies, they reported a 68% increase in prostate cancer for those who drink cow’s milk (9).
Acne
Currently, acne is an epidemic in industrialized countries, as roughly 85% of teenagers suffer from this skin condition. While many people believe acne to be a normal indicator of hormonal changes in adolescence, our diet significantly affects the health of our skin (10).
As it turns out, there is “substantial epidemiological and biochemical evidence supporting the effects of...dairy products as enhancers of...acne aggravation” (11).
In one study of 4,273 teenage boys, researchers found a positive association between skim milk consumption and acne, as the hormones found in cow’s milk can cause biological effects in humans (12).
When we consume dairy products, we stimulate an enzyme in our body known as mTORC1, which contributes to acne and obesity. While a diagnosis of acne isn’t life threatening, it can be a visible sign of future chronic disease.
Persistent over-activation of the mTORC1 enzyme promotes a variety of diseases later in life, including type-2 diabetes, cancer, and neurodegeneration (13).
The issue is that dairy products are designed to stimulate mTORC1. The stimulation of mTORC1 is beneficial when we are drinking human milk as infants because we need to grow at a much faster rate than we do in adulthood.
But when we drink cow’s milk, we are drinking formula made for baby calves, who grow 40x faster than breast-fed human infants. As a result, dairy consumption leads to over-stimulation of mTORC1 in humans (14).
The Pegan diet’s exclusion of dairy products may not only reduce blemishes on our skin, but it may protect us from developing chronic diseases as we age.
4. Avoidance Of Junk Food
The Pegan diet emphasizes the consumption of whole foods rather than processed foods. For example, a potato is a whole food, whereas potato chips are processed foods. Processed foods are high in added sugar, sodium, saturated fat, and unhealthy oils. On the other hand, whole foods contain far more antioxidants, fiber, vitamins, and minerals.
Junk food is simply the wrong fuel for the human body. When we eat a lot of it, we tend to develop disease over time. Therefore, we should focus on replacing junk food with healthy foods like fruits and vegetables.
According to the World Health Organization, approximately 2.8 million deaths each year are linked to low fruit and vegetable consumption.
In addition, other researchers have found that if only half of the United States population were to eat just one more serving of fruits and veggies every day, an estimated 20,000 new cancer cases might be avoided (15). Clearly, this is a life and death situation. Thankfully, the Pegan diet is full of health promoting whole plant foods and very low on junk food.
Summary: The Pegan diet is full of whole plant foods and eliminates many animal foods, including dairy. As a result, it can help to reduce your risk of heart disease and prostate cancer, as well as boost your mood.
Cons Of The Pegan Diet
1. Restricted Intake Of Legumes
Without citing any evidence, Dr. Hyman warns us to “stay away from big, starchy beans." This restriction of bean consumption is easily the most significant downside to the Pegan diet. According to researchers from the National Ageing Institute in Australia, legumes are the “most important dietary predictor of survival in older people [across cultures]” (16). But why does eating beans make us live longer?
Beans are some of the healthiest foods on the planet, in part, because they contain so much fiber. By its definition, fiber is only found in plant foods. Just one serving of black beans contains 14 grams of fiber.
According to the USDA, less than 3% of Americans eat the recommended daily intake of fiber of just 25-30 grams (17). This deficiency is a major issue in the United States, as dietary fiber protects against cardiovascular disease, diabetes, obesity, and a number of other chronic diseases (18).
While we should eat plenty of beans, we should start slowly to allow our digestive system to adjust to the increased roughage. The key is to slowly add more beans to our diet, waiting a few days in between making further changes. Drinking lots of fluids is also important as you begin to eat more fiber.
2. Restricted Intake Of Whole Grains
The Pegan diet also tells us to avoid consuming gluten and other grains. The question is, why? First, let’s tackle the issue of gluten, the main protein found in wheat. Currently, the “gluten-free” movement is big business in the United States, as millions of people are demanding gluten-free versions of their favorite foods.
But is this just a trend or is gluten truly causing health problems?
There are three groups of people who should completely avoid or limit their consumption of gluten:
- Roughly 0.1% of the population has a wheat allergy, which occurs when our body has an allergic reaction to a variety of proteins found in wheat (19).
- About 0.71% of the population has celiac disease, which is a specific allergy to gluten (20).
- There are some people who are not allergic to wheat or gluten, yet still experience gastrointestinal symptoms and other bodily issues when consuming gluten. This group of people suffers from non-celiac gluten sensitivity (NCGS). While scientists initially questioned the legitimacy of this condition, double blind randomized controlled trials have confirmed its existence (21). Estimates indicate that approximately 1-1.5% of the population suffers from NCGS (22).
All in all, only about 2% of people should consider limiting or eliminating wheat from their diet. For the rest of the population, the scientific literature indicates that whole grains should be consumed liberally.
In fact, a 2012 study in the Journal of the Academy of Nutrition and Dietetics found that “there is no evidence to suggest that following a gluten-free diet has any significant benefits in the general population” (23).
On the contrary, a gluten-free diet may negatively affect our health. For most people whole-grain intake protects against cancer, heart disease, diabetes, and obesity. Whole grain consumption also helps to create a healthy composition of gut bacteria, which reduces inflammation in our gut and protects against certain cancers (24).
Clearly, the Pegan diet’s recommendation of eliminating starches and whole grains does not reflect the scientific consensus that whole grains are one of the healthiest foods for the human body.
3. Inclusion Of Animal Foods
We use the saying “everything in moderation” to comfort us as we indulge in unhealthy foods such as cake, fried fish, deli meat, etc. But what if moderation can kill us? Roughly 650,000 people die from heart disease every year in the United States, which represents one in every four deaths (25).
Simply put, this is not normal. In fact, few people, if any, should ever develop heart disease. For instance, in parts of rural China, heart disease is extremely rare. According to Dr. Michael Greger, this rarity can be attributed to the “extraordinarily low cholesterol levels among these populations” (26).
It could be possible that people in rural China have genes that protect against heart disease. However, we know that people tend to develop diseases as they migrate from a low-risk area (i.e., Japan) to a high-risk area (i.e., the United States) (27). Therefore, diet and lifestyle prove to be more important than genetics alone.
So, how much cholesterol is too much cholesterol? According to Dr. Caldwell Esselstyn, “coronary disease is practically unheard of when total serum cholesterol levels are 90-150 mg/dL” (28). In other words, if we keep your cholesterol levels below 150 mg/dL, we are unlikely to ever develop heart disease.
Roughly 35% of heart attacks occur in patients with cholesterol levels between 150-200 mg/dL (29). If all Americans kept their cholesterol levels below 200 mg/dL, as the American Heart Association recommends, thousands of people would die (30).
The Pegan diet was created to offer a more “moderate” choice for those who believe eating only plant foods is extreme. However, a strictly plant-based diet is the only diet ever to have reversed heart disease (7).
While the Pegan diet is certainly much healthier than the standard American diet, it may still lead to millions of deaths, as people continue to eat animal foods loaded with cholesterol and saturated fats.
Instead of living by the phrase, “everything in moderation,” we should be educated on the foods that are optimal for our health and those that can put us at risk for disease. When we live by the saying, “everything in moderation,” we experience heart disease in moderation.
Summary: The Pegan diet restricts our consumption of beans and whole grains, two of the healthiest foods on the planet. In addition, it promotes the consumption of meats in moderation. Yet, we know that those who eat cholesterol-laden foods in moderation still develop heart disease, the number one cause of death in the United States.
Conclusions
The Pegan diet represents a significant improvement over the standard American diet. However, the balance of available scientific evidence demonstrates that Dr. Hyman’s restrictions on whole grains and legumes are unsubstantiated. In the world of nutrition, so-called “experts” often attempt to create a new diet or product to make money.
For example, on Dr. Hyman’s website, we can purchase a “10 Day Reset” package for a whopping $250. Instead of adopting these trendy, fad diets (that always claim to not be fad diets), we can simply choose to eat a variety of healthy foods to protect ourselves against chronic disease.
Final conclusion: Instead of implementing the restrictive limitations of the Pegan diet, we should fill our diets with an abundance of whole plant foods such as fruits, vegetables, whole grains, and beans.
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