The Paleo Diet

by Cordain, Loren

  One of our most powerful therapies to calm down the inflammation of both Crohn’s disease and ulcerative colitis (an inflammatory disease of the colon) is to prescribe fish oil capsules—an excellent source of omega 3 fats. Once again, we find that multiple elements in humanity’s original diet complement one another to eliminate or prevent chronic illness. And it is our deviation from the three simple foods (fruits, vegetables, and lean meats) we are genetically adapted to eat that invariably causes us trouble and ill health.

  Inflammatory Diseases

  Omega 3 fats are powerful weapons in other wars as well. Perhaps because of their anti-inflammatory properties, they may prevent cancer from developing. They are also extremely effective in calming down virtually all inflammatory diseases—illnesses that end in “itis,” such as rheumatoid arthritis, ulcerative colitis, and gingivitis. These amazingly healthful fats can even reduce symptoms of certain autoimmune diseases: the combination of supplementing your diet with omega 3 fats and eliminating grains, dairy foods, legumes, potatoes, and yeast may substantially reduce the severity of symptoms of these diseases.

  Autoimmune Diseases

  Autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, and type 1 (juvenile) diabetes develop when the body’s immune system can’t tell the difference between its own tissues and those of foreign invaders. The result: the body attacks itself. The type of disease depends on the nature of the body’s assault: When the immune system invades and destroys nerve tissue, multiple sclerosis and other neurological diseases develop. When the pancreas is the target, type 1 diabetes occurs. When joint tissues are attacked and destroyed, the result is rheumatoid arthritis.

  All autoimmune diseases develop because of interactions between the genes and one or more environmental factors, such as a viral or bacterial infection or exposure to a certain food. No one knows exactly how viruses, bacteria, and foods can spark the disease in genetically susceptible people, but research from our laboratory increasingly implicates recently introduced Neolithic foods such as grains, legumes, dairy foods, potatoes, and other members of the nightshade family.

  Many environmental agents have been suspected in the development of autoimmune diseases. But only one of these types has proved capable of causing a disease. Cereal grains—such as wheat, rye, barley, and oats—are responsible for celiac disease and dermatitis herpetiformis. In celiac disease, the immune system attacks and destroys cells in the intestine, leading to diarrhea and many nutritional problems. In dermatitis herpetiformis, the skin is attacked.

  Withdrawal of all gluten-containing cereals causes complete remission of both diseases. Cereal grains, dairy products, and legumes are suspected in other autoimmune diseases, such as type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. To date, no dietary intervention studies have been conducted to see whether Paleo diets—free of grains, dairy products, and legumes—can reduce the symptoms of these diseases. However, anecdotal reports from Canada show improvement in symptoms of multiple sclerosis patients following the Paleo Diet.

  Lectins and Autoimmune Disease

  My research group and I have published a paper in the British Journal of Nutrition describing our theory that dairy foods, grains, legumes, and yeast may be partly to blame for rheumatoid arthritis and other autoimmune diseases in genetically susceptible people. Legumes and grains contain substances called lectins. These substances are proteins that plants have evolved to ward off insect predators. Lectins can bind with almost any tissue in our bodies and wreak havoc—if they can enter the body, that is.

  Normally, when we eat food, all proteins are broken down into basic amino acid building blocks and then absorbed in the small intestine. Lectins are different. They are not digested and broken down; instead, they attach themselves to cells in our intestines, where nutrient absorption takes place. The lectins in wheat (WGA), kidney beans (PHA), soybeans (SBA), and peanuts (PNA) are known to increase intestinal permeability and allow partially digested food proteins and remnants of resident gut bacteria to spill into the bloodstream. (Alcohol and hot chili peppers also increase intestinal permeability.) Usually, special immune cells immediately gobble up these wayward bacteria and food proteins. But lectins are cellular Trojan horses. They make the intestines easier to penetrate, and they impair the immune system’s ability to fight off food and bacterial fragments that leak into the bloodstream.

  Surprisingly, we have found that many common gut bacteria fragments are made up of the same molecular building blocks as those found in certain immune system proteins and in the tissues under attack by the immune system. This matchup—of gut bacteria or food protein, immune system protein, and body tissue protein—may confuse the immune system, causing it to attack the body’s own tissues. A number of research groups worldwide have found that milk, grain, legume, and nightshade proteins can also trick the immune system into attacking the body’s own tissues by this process of molecular mimicry.

  If you have an autoimmune disease, there is no guarantee that diet will cure it or even reduce your symptoms, but there is virtually no risk, and there are many other great benefits from the Paleo Diet that will improve your health.

  Psychological Disorders

  One of the least known benefits of grain-free diets is their ability to improve mental well-being. My colleague Dr. Klaus Lorenz of Colorado State University has extensively studied how cereals may influence the development and progression of schizophrenia. In a wide-ranging review study, Dr. Lorenz concluded that in “populations eating little or no wheat, rye and barley, the prevalence of schizophrenia is quite low.” Dr. Lorenz’s analysis included the clinical studies by Dr. F. Curtis Dohan of the Eastern Pennsylvania Psychiatric Institute. In studies spanning almost twenty-five years, Dr. Dohan reported time and again that the symptoms of schizophrenia were reduced in patients on grain-and dairy-free diets but worsened when these foods were returned to the diet. Exactly why cereals may alter mood and mental well-being is not entirely clear. But several studies have shown that when wheat is digested, it contains a narcoticlike substance that may affect certain areas in the brain that influence behavior. Similar substances called “casomorphins” have been isolated from cow’s milk; however, no one knows whether they can alter mood or behavior.

  My colleague Joe Hibbeln at the National Institutes of Health has demonstrated that omega 3 fats may be effective in reducing depression, hostility, schizophrenia, and other mental disorders. His finding was confirmed in a four-month study of thirty manic-depressive patients by Dr. Andrew Stoll of the Brigham and Women’s Hospital in Boston. Dr. Stoll used medicine’s most powerful study tool, a double-blind, placebo-controlled trial, to compare the efficacy of omega 3 fats versus olive oil for treatment of manic-depressive illness. According to Dr. Stoll and his colleagues, “for nearly every outcome measure, the omega 3 fatty acid group performed better than the placebo group.” This work lends credence to a number of recent studies demonstrating that the symptoms of depression are much lower in people who eat a lot of fish (an excellent source of omega 3 fats).

  The Paleo Diet will also improve your mental outlook because it normalizes your insulin level. Almost everyone knows that a low blood sugar level can make you feel tired, irritable, and tense. When you normalize your insulin level with low-glycemic carbohydrates and plenty of lean protein, your blood sugar level will be more even throughout the day and so will your mood.

  Vitamin-Deficiency Diseases

  In the United States the common vitamin deficiency diseases (beriberi, pellagra, and rickets) were wiped out after World War II with the wide-scale fortification of our white flour and white rice with B vitamins and our milk and margarine with vitamin D. However, people living in less developed nations are not so lucky; these diseases still run rampant wherever diets are heavily based on cereals and legumes. It goes without saying that the world’s primary vitamin deficiency diseases, including scurvy from a lack of vitamin C, are completely a result of agriculture’s new foods. W
hen you eat the way nature intended, you will protect yourself from all illnesses that develop from vitamin deficiencies.

  Dental Cavities

  Nearly all archaeological studies of Paleolithic people’s teeth show them to be almost completely free of cavities. How can this be when they never brushed, gargled with mouthwash, or flossed? The answer is simple: with their diet of lean meats, fruits, and veggies, cavities simply couldn’t get a foothold. Historically speaking, cavities and tooth decay didn’t start until the coming of agriculture and its starchy, sugary foods. Cavities are caused when acid produced by certain bacteria eats away part of the enamel of your tooth. These bacteria can’t set up shop in your teeth unless there is a constant source of sugar or starch that fuels their acid production.

  We can learn a lot from our teeth because any food that does so much damage to our teeth can’t be very good for the rest of our bodies, either. Refined sugars and starches are foreign substances to our Paleolithic bodies. We simply haven’t had time to adapt to agriculture’s new foods. We are best designed to run on the foods nature provided: lean meats, fruits, and veggies.

  Alcoholism

  Alcohol—and its enormous potential for abuse—was not part of the preagricultural equation. No alcoholic beverage has ever been linked to Paleolithic people, although it would have been possible to make alcoholic drinks from gathered honey (mead) or berries (wine) by natural fermentation. It wasn’t until the Agricultural Revolution, with its abundance of starchy grains, that the first beers were brewed on a regular basis. Quite a bit later came wine, made from fermented grapes. (Because beer and wine are yeast fermentation by-products, they do not contain more than about 6 to 13 percent alcohol; the alcohol-producing yeast organisms die when the alcohol concentration rises above this level.) Hard liquor didn’t come on the scene until about 800 A.D., with the invention of distillation.

  In most Western countries, moderate consumption (five to ten drinks per week) of alcohol is not considered detrimental to health; in fact, it has been associated with a reduced risk of dying from all combined causes of death. Moderate alcohol consumption also may improve your insulin sensitivity and is associated with a reduced risk of other chronic diseases.

  Does this mean you should take up drinking to improve your health? Absolutely not. You don’t need alcohol to obtain the health and weight-loss benefits of the Paleo Diet. However, if you currently enjoy an occasional glass of wine, there is no need to forgo this pleasure. Consumption of alcoholic beverages a few times a week won’t hurt your health, nor will it slow your weight loss. However, if you suffer from an autoimmune disease or another serious health problem, alcoholic beverages should not be part of your dietary equation.

  Skin Cancers

  Skin cancers come in three basic varieties:• Squamous cell cancers, which form on the top layers of the skin

  • Basal cell cancers, which form on the bottom layers of the skin

  • Melanomas, which form within the skin’s pigment-producing cells, the melanocytes

  The American Cancer Society estimated that 2 million Americans would develop the first two types of skin cancer in the year 2010. These cancers grow slowly, rarely spread to other areas of the body, and are easily curable by early removal. An estimated 69,000 Americans were expected to develop melanoma in 2009. If detected early and surgically removed before they spread to other parts of the body, melanomas are highly curable, with 95 out of 100 people alive five years after diagnosis. But if melanomas spread to the rest of the body, they can be deadly; the five-year survival rate drops drastically, to 16 out of 100.

  Scientists know that excessive sunlight exposure is linked to all three cancers. But this does not mean you should avoid sunlight in any amount. Here again, the experience of our hunter-gatherer ancestors proves helpful. Ironically, many studies have shown that people with high lifetime sunlight exposure (similar to that of hunter-gatherers) have lower rates of melanoma than those with low sunlight exposure. Also, indoor workers have a greater risk of developing melanoma than outdoor workers do. Even more puzzling, melanomas often arise in body areas that are infrequently or intermittently exposed to the sun. These unexpected findings have led researchers to believe that severe sunburn during childhood, or intense burns in body areas that are infrequently or intermittently exposed to the sun, may be more important in the development of melanoma than cumulative exposure during adulthood.

  When your exposure to sunlight is gradual, moderate, and continuous—if you don’t get excessive sunburn—your body responds in a manner guided by evolutionary wisdom. The skin begins to tan from increased production of melanin, and the darkened skin provides protection from the sunlight’s damaging ultraviolet rays. Also, vitamin D levels in the blood begin to rise as ultraviolet light strikes the skin, causing it to convert cholesterol into vitamin D.

  Vitamin D is a potent inhibitor of the cancer-causing process. In fact, vitamin D has been shown to prevent the growth of melanomas in experimental animals and cultured tissue lines.

  An unexpected bonus of vitamin D is that it may also be one of our most important allies in the war against prostate, breast, and colon cancers. Evidence from population studies confirms that people with the greatest lifetime sun exposures have the lowest rates of these cancers.

  Skin cancer is a complex disease, with several factors influencing its ultimate course. In laboratory animals, scientists have found that excessive omega 6 fats promote the development of skin cancer—but omega 3 fats slow it down. Furthermore, antioxidants like beta-carotene, vitamin C, and vitamin E tend to prevent the sun’s ultraviolet damage to the skin. You can get these same dietary advantages when you adopt the dietary principles I have laid out in the Paleo Diet. (Note: As with many of the diseases we have discussed, proper diet reduces your risk of developing some types of skin cancer, but it cannot completely prevent it.)

  Exposure to sunlight is natural for human beings. It is part of our evolutionary heritage. Without sunlight, it is virtually impossible to achieve an adequate intake of vitamin D from the natural foods that were available to our hunter-gatherer ancestors. Our food supply has been a significant source of vitamin D for a very short time—less than a century, when dairy producers began adding it to milk and, later, margarine. Sunlight exposure is healthy as long as it occurs in a slow, gradual, and limited dose over the course of a lifetime.

  As you have seen, the Paleo Diet will not only help you get thin; it will also help prevent and treat a broad range of diseases. The Paleo Diet is good medicine!

  PART THREE

  The Paleo Diet Program

  7

  Eating Great: What to Eat, What to Avoid

  Now that I’ve talked about why the Paleo Diet is the diet nature intended, let’s get down to specifics: how do you get started?

  This is the best part—it’s so easy. You don’t have to balance food blocks, weigh portions, keep a food log, or count calories. As I’ve shown, the basic guidelines of the Paleo Diet are very simple : all the lean meats, poultry, fish, seafood, fruits (except dried fruits), and vegetables (except starchy tubers—primarily, potatoes) you can eat. Because the mainstay of the Paleo Diet is high-quality, low-fat protein, you won’t need to feel guilty about eating lean meat, fish, or seafood at every meal. This is exactly what you should be doing, along with as many low-glycemic fruits and veggies as you want.

  You’re about to embark on a diet of enormous and bountiful diversity, fully backed by thousands of clinical nutrition trials and—most important—by 2.5 million years of evolutionary experience. What do you get in return? If you follow the simple nutritional guidelines laid out in this chapter and spelled out in the next two chapters with tempting meal plans and delicious, easy recipes, you will lose weight; reduce your risk of heart disease, cancer, diabetes, and other chronic diseases; and feel energized all day long. And unlike with almost every other diet you can think of, you won’t feel hungry all the time. You will feel good on this diet, because this is the on
ly diet that is consistent with your genetic makeup.

  By imitating the diets of our Paleolithic ancestors with foods you can buy at the supermarket or grow in your own garden, you’ll be able to reap the health benefits that are your genetic heritage—freedom from obesity, a high energy level, and excellent health.

  It is not possible for us to duplicate precisely all the foods that our ancient ancestors ate. Many of these foods no longer exist—such as the mammoth—or they’re unavailable commercially, or they just aren’t palatable, given our modern tastes and cultural traditions. However, most of the advantages and benefits of the Paleo Diet can easily be obtained from common foods following the general nutritional guidelines observed by our Paleolithic ancestors.

  Making the Diet Work for You

  It isn’t easy to change the habits of a lifetime, and you don’t have to do it overnight. You can ease the transition by adopting the three levels of the Paleo Diet. The levels are based on the concept that what you do occasionally won’t harm the overall good of what you do most of the time. Does this mean you can cheat? Yes—sometimes. Occasional cheating and digressions may be just what you need to help you stick to the diet the rest of the time, and they won’t sidetrack the weight loss and health effects of this diet.

  Getting Enough of the Right Foods

  As I discussed earlier, there was no single Paleo diet. Our ancient ancestors made the most of their environment wherever they happened to be. For example, the Inuit people were able to live healthy lives, free of chronic diseases, on a diet that derived at least 97 percent of its energy from animal foods. At the other end of the spectrum were groups like the !Kung in Africa, who obtained 65 percent of their daily calories from plant foods (chiefly the mongongo nut). However, most Paleolithic groups fell somewhere in between, with animal foods generally making up around 55-60 percent of the daily caloric intake. On the Paleo Diet, you should attempt to get a little more than half of your calories from lean meat, organ meats, fish, shellfish, and poultry and the rest from plant foods.