The Paleo Diet (10 page)

Cut the fat! If the nutritional experts have had an overriding message over the last decades, this is it.

The thing is, this dictum is flat-out wrong. We now know that it’s not
how much
fat you eat that raises your blood cholesterol levels and increases your risk of heart disease, cancer, and diabetes—it’s the
kind
of fat you eat. We consume too many omega 6 polyunsaturated fats at the expense of the healthful omega 3 kind. And we get plenty of those cholesterol-raising, artery-clogging trans-fatty acids found in margarine, shortening, and many processed foods. Finally, we eat excessive amounts of palmitic acid, a blood cholesterol-raising saturated fat found in cheeses, baked goods, and fatty processed meats, such as hot dogs, bacon, bologna, and salami.

All of those kinds of fat are bad and need to go. But in removing all fats from our diet, we are doing more harm than good. This problem is easy to solve: With the Paleo Diet—which contains healthful fats—you will automatically reestablish the proper balance of fats in your diet. You’ll also lower your blood cholesterol and reduce your risk of heart disease, cancer, and other chronic illnesses.

From our analyses of the fats in wild animals, my research team and I have found that even though ancient humans ate meat at nearly every meal, they consumed about half of the palmitic acid found in the average Western diet. (Wild game meat is low in total fat and palmitic acid and high in healthful, cholesterol-lowering monounsaturated fat and stearic acid.) They also ate lots of omega 3 polyunsaturated fats.

See Appendix 2 for a table contrasting the fats in domestic and wild meats.

The ratio of omega 6 to omega 3 fats in Paleo diets was about 2 to 1; for the average American, the ratio is much too high—about 10 to 1. Eating too many omega 6 fats instead of omega 3 fats increases your risk of heart disease and certain forms of cancer; it also aggravates inflammatory and autoimmune diseases. The lean meats, fish, fruits, vegetables, and oils found in the Paleo Diet guarantee that you will have the proper ratio of omega 6 and omega 3 fats—and of all other fats.

Cereal grains are low in fat. But the little fat they do have is unbalanced—tilted heavily toward omega 6. For example, in game and organ meat, the average ratio of omega 6 to omega 3 is 2 or 3 to one. In eight of the world’s most commonly consumed cereals, this ratio is a staggering 22 to 1.

Cereal grains also have contributed to generations of blubbery cows that bear little resemblance to the lean wild animals our ancestors ate. Grain-fed cows have become loaded down with palmitic acid; worse, the fats in their meat have taken on the same high omega 6 to omega 3 ratio that’s in their grain.

Dairy foods have taken a further toll on humanity’s health over the last 9,000 years or so. Milk, cream, cheese, butter, and fermented milk products (including yogurt), ice cream, and the many processed dairy products of the twentieth century are some of the richest sources of certain saturated fats in the typical Western diet. In particular, fatty dairy foods contain palmitic and myristic fatty acids—two substances that elevate blood cholesterol. When you evaluate dairy products for fat percentage by calories, butter is the worst at 100 percent fat. Cream is 89 percent fat, cheeses average about 74 percent fat, and whole milk is about 49 percent fat. And most of the fats in these dairy products—about 40 percent—are the bad saturated fatty acids. Despite their wholesome image, whole milk and fatty dairy products are some of the least healthful foods in our diets. Their fatty acids (palmitic acid and myristic acid) raise your blood cholesterol; they also raise your risk of developing heart disease and other chronic illnesses.

The next major misstep in food innovation happened just a few decades ago, when vegetable oils became part of our diet.

In the 1940s and 1950s, when most of these vegetable oils were introduced, nobody realized that the
ratio
of omega 6 to omega 3 fats was terribly important to health. What food scientists knew at that point was pretty simple—that polyunsaturated fats lowered blood cholesterol. And it was with this limited piece of the total picture that they happily created a great variety of cooking and salad oils that were highly polyunsaturated—but regrettably also extremely high in omega 6 fats. The worst offenders are safflower oil and peanut oil (with extremely high omega 6 to omega 3 ratios), cottonseed oil, sunflower oil, sesame oil, and corn oil. Walnut oil is more balanced. And flaxseed oil is better still—low in omega 6 fats and high in omega 3.

Cooking and salad oils are just part of the high omega 6 problem. Nearly all processed foods—breads, cookies, cakes, crackers, chips, doughnuts, muffins, cereals, and candies—and all fast foods are cooked with some form of high omega 6 vegetable oil. Worse, many of these foods are still made with hydrogenated vegetable oils that contain harmful trans-fatty acids. Trans fats raise blood cholesterol and increase your risk of developing heart disease. A study published in the
American Journal of Public Health
concluded that consumption of trans fats by Americans was responsible for more than 30,000 deaths annually from heart disease. Trans fats are found in margarine, shortening, and some peanut butters—foods that definitely were not part of humanity’s original diet.

Paleo diets were exceptionally rich in potassium and low in sodium. Just about everything Paleolithic people ate—meats, fish, fruits, vegetables, nuts, and seeds—contained about five to ten times more potassium than sodium. This means that when you eat only fresh, unprocessed food, it’s impossible to consume more sodium than potassium.

We don’t know exactly when farmers began to include salt in their diet, but we can guess why. Salt performed a great service, in the centuries before refrigeration, in preserving meats and other foods. It helped make foods like olives edible; it added flavor to bland cereals and other foods. At least 5,600 years ago, archaeological evidence shows us, salt was mined and traded in Europe. It remains a staple today; in fact, the average American consumes about twice as much sodium as potassium. And that’s not healthy.

Very few people—including nutritionists and dietitians—are aware that the acid-base content of your food can affect your health. Basically, this is what happens: everything you digest eventually reports to the kidneys as either an acid or an alkaline base. Acid-producing foods are meats, fish, grains, legumes, dairy products, and salt. Alkaline-producing foods are fruits and vegetables. You need both kinds—acid and alkaline. Fats are generally neutral.

The average American diet is slightly acidic—which means that our kidneys must handle a net acid load. For example: Suppose you have a typical “light” lunch, probably available at a dozen places near your home or office, of pepperoni pizza and a small salad with Caesar dressing. This meal is a disaster for the body’s acid-base balance: the pizza’s white-flour crust, melted cheeses, and salty pepperoni are all highly acidic. Add salt, and you make it even more acidic. Any alkaline remnant available in the tiny salad is neutralized by the salt and cheese in the Caesar salad dressing.

In the long run, eating too many acid foods and not enough alkaline foods can contribute to bone and muscle loss with aging. There are more immediate dangers, too: excessive dietary acid can raise blood pressure and increase your risk of developing kidney stones. It can also aggravate asthma and exercise-induced asthma.

The Paleo Diet is rich in vitamins and minerals. One of the best ways to prove how healthy our diet used to be is to show what happened when our ancestors fiddled with it.

Vitamin C deficiency,
a disease unknown to Paleolithic people, causes scurvy. Paleolithic people didn’t have this problem; their diets were extremely high in vitamin C (around 500 milligrams per day) because they ate so many fresh fruits and vegetables. But even Eskimo groups—who for thousands of years have eaten virtually no plant foods for most of the year—didn’t get scurvy. How can this be? They got their vitamin C from other natural sources—raw fish, seal, and caribou meat.

But as our ancestors began eating more cereal grains and fewer lean meats, fresh fruits, and vegetables, they lost much of the vitamin C in their diets. Cereal grains have no vitamin C, which is one of the body’s most powerful antioxidants. Vitamin C helps lower cholesterol, reduces the risk of heart disease and cancer, boosts the immune system, and helps ward off infections and colds.

Vitamin A deficiency,
like scurvy, could only have emerged after the coming of agriculture. Paleo diets were always rich in fruits and vegetables—excellent sources of beta-carotene, a nutrient that can be converted to vitamin A by the liver. (Our ancient ancestors also ate the entire carcasses of the animals they hunted and killed, including the vitamin A-rich liver.) Again, trouble happened when cereals took over and fresh fruits, vegetables, and organ meats were pushed aside. Vitamin A is essential for all of the body’s mucous membranes. Vitamin A deficiency results in a condition called “xerophthalmia” (dry eyes), which can lead to blindness; in fact, this is the leading cause of blindness in children worldwide. Vitamin A deficiency also impairs the body’s ability to fight infection and disease.

Vitamin B deficiency
is another problem. Many people believe that whole-grain cereals are rich sources of B vitamins. They’re mistaken. Compared to lean meats, fruits, and vegetables, calorie for calorie, cereals are vitamin B lightweights. Even worse, as I mentioned earlier, whole grains and legumes contain antinutrients that block the absorption of B vitamins in the intestines. For instance, antinutrients called “pyridoxine glucosides” can prevent your body from getting as much as two-thirds of the vitamin B
₆
you eat. In a study of vegetarian women from Nepal, Dr. Robert Reynolds, of the USDA Human Nutrition Research Center, linked the low vitamin B
₆
levels in these women to the high levels of pyridoxine glucosides in their grain- and legume-heavy diets. In contrast, the availability of vitamin B
₆
in lean meats is nearly 100 percent.

Another B vitamin that’s poorly absorbed when you eat whole grains is biotin. Experiments by my colleague Dr. Bruce Watkins from Purdue University have shown that wheat and other whole grains impair the body’s ability to get enough biotin. Biotin deficiencies result in dry, brittle fingernails and hair. Research by Dr. Richard K. Scher and colleagues at Columbia University has shown that biotin supplements reduce fingernail brittleness and vertical “ridging” in nails. But you won’t need to supplement your diet if you get enough biotin (or any other vitamin or mineral) the old-fashioned way—by eating the right foods. The availability of biotin from animal foods is almost 100 percent.

Pellagra and beriberi are two of the most devastating and widespread B vitamin deficiency diseases that have ever plagued human-kind. They are caused exclusively by excessive consumption of cereals. Pellagra is a serious, often fatal, disease caused by a lack of the B vitamin niacin and the essential amino acid tryptophan. In a sad chapter of U.S. history, between 1906 and 1940 there was an epidemic of pellagra in the South. An estimated 3 million people developed it, and at least 100,000 of them died. Similar outbreaks have occurred in Europe and India, and pellagra is still common in parts of Africa.

Underlying every worldwide pellagra epidemic was excessive consumption of corn. Corn has low levels of both niacin and tryptophan, and the tiny amounts of niacin that are present are poorly absorbed. Pellagra could never have happened in the Paleolithic era, because lean meats are excellent sources of both niacin and tryptophan. Invariably, whenever we stray from the lean meats, fruits, and vegetables that we are genetically adapted to eat, ill health is the result.

Beriberi, caused by a deficiency of vitamin B
₁
(thiamin), ultiately causes paralysis of the leg muscles. This disease was virtually unknown until the introduction of polished rice in the late 1800s. In parts of Japan and Southeast Asia, where rice was the staple food, beriberi became epidemic as people replaced their traditional brown rice with white rice. Eventually, scientists discovered that removing the thiamin-containing bran during the polishing process was largely responsible for this disease. Beriberi has been mostly eliminated with the introduction of “enriched” rice, to which vitamin B
₁
is added. However, the message should be clear: If we have to add 1 a vitamin to a food to prevent it from causing ill health and disease, we shouldn’t be eating it in the first place.

In North America, we enrich our refined cereal grains with vitamin B
₁
and niacin—which means you will never have to worry about pellagra or beriberi. But it doesn’t mean that these foods are good for you. Far from it. Within the past twenty years, a major risk factor for heart disease has surfaced. It has been found that low dietary intakes of three B vitamins—B , B
₁₂
, and folate—increase your blood level of an amino acid called homocysteine. A high blood level of homocysteine, in turn, increases your risk of heart disease. Whole-grain cereals have no vitamin B
₁₂
, their vitamin B is poorly absorbed, and they are at best a meager source of folate. So excessive consumption of whole-grain cereals instead of lean meats, fruits, and vegetables is a formula for disaster for your heart. Again, lean meats are rich sources of vitamins B and B , and fresh fruits and vegetables are our best food sources of folate. By eating the foods nature intended, you will never have to worry about your B vitamin status, homocysteine level, and heart disease.