The Paleo Diet (14 page)

Two risk factors for breast cancer are early onset of puberty and above-average height. It is entirely possible that the same high insulin levels that elevate IGF-1 and lower IGFBP-3 (in other words, the levels that make children taller and make puberty happen sooner during childhood) also increase susceptibility to cancer during adulthood.

Many women, worried about breast cancer, have adopted vegetarian diets in an attempt to reduce their risk. Unfortunately, it may be that these grain- and starch-based diets actually increase the risk of breast cancer, because they elevate insulin—which, in turn, increases IGF-1 and lowers IGFBP-3. A large epidemiological study of Italian women, led by Dr. Silvia Franceschi, has shown that eating large amounts of pasta and refined bread raises the risk of developing both breast and colorectal cancer.

Most vegetarian diets are based on starchy grains and legumes. Sadly—despite continuing perceptions of these as healthy foods—vegetarian diets don’t reduce the risk of cancer. In the largest-ever study comparing the causes of death in more than 76,000 people, it was decisively shown that there were no differences in death rates from breast, prostate, colorectal, stomach, or lung cancer between vegetarians and meat eaters.

Cancer is a complex process involving many genetic and environmental factors. It is almost certain that no single dietary element is responsible for all cancers. However, with the low-glycemic Paleo Diet, which is also high in lean protein and health-promoting fruits and vegetables, your risk of developing many types of cancer may be very much reduced.

Because insulin resistance changes the hormonal profile of the blood to one that facilitates tissue growth, scientists have good reason to suspect that insulin resistance lies at the root of any disease in which abnormal tissue growth occurs. One extremely common such disease is myopia—nearsightedness—which affects an estimated one-third of all Americans. Myopia results from excessive growth of the eyeball. Although the eye looks normal from the outside, inside it’s too long for the eye to focus properly. Myopia typically develops during the childhood growth years and usually stabilizes by the time people reach their early twenties. New evidence that implicates insulin resistance in the childhood development of myopia may be useful in preventing nearsightedness in young children.

Eye doctors generally agree that nearsightedness results from an interaction between excessive reading and your genes. If you spent your youth with your nose in a book and if nearsightedness runs in your family, chances are good that you’re now wearing glasses or contact lenses. Myopia is thought to stem from a slightly blurred image on the back of your eye (the retina) that’s produced as you focus on the written page. This blurred image causes the retina to send out a hormonal signal telling the eyeball to grow longer. Experiments in laboratory animals suggest that the hormonal signal is produced by retinoic acid. Excessive reading slows the retina’s production of retinoic acid, a substance that normally checks or prevents the eyeball from growing too long. Additionally, recent research shows that elevated insulin also directly contributes to the excessive growth of the eyeball. This may mean that if your children’s diet prevents insulin resistance during growth and development, their risk of developing myopia may be lower.

Polycystic ovary syndrome (PCOS) affects 5 to 10 percent of all North American women. Women with PCOS ovulate irregularly or not at all, and their ovaries produce high levels of male hormones such as testosterone. Women with PCOS are prone to obesity, excessive body hair, acne, high blood pressure, and type 2 diabetes. They also have a seven times greater risk of heart disease and heart attack than other women do. Almost 60 percent of all women with PCOS are insulin resistant, and most of these women have elevated levels of IGF-1. Numerous clinical studies have shown that simply changing the diet—eating foods that improve insulin metabolism—can reduce many of the symptoms of PCOS. The Paleo Diet, which normalizes insulin metabolism, can greatly help women with this problem.

For years, many dermatologists believed that diet had absolutely nothing to do with acne. But very new scientific evidence has linked insulin resistance to acne. Diets loaded with sugar, fructose, and high-glycemic carbohydrates may contribute to this problem, which can be devastating. Between 40 and 50 million American teens and adults have acne.

Some striking information to support the link between acne and diet comes from Dr. Otto Schaefer, who spent his entire professional career in the wilderness of the Canadian Far North, working with Inuit natives who literally were transferred from the Stone Age to the Space Age in a single generation during the 1950s and 1960s. Dr. Schaefer reported that in those Eskimos who ate their traditional foods, acne was absent. Only when they adopted Western foods laced with refined sugars and starches and dairy products did acne appear.

Four things happen when acne develops: First, there’s accelerated growth of the skin surrounding the hair follicle (called “follicular hyperkeratosis”). Second, oil (sebum) production speeds up within the follicle. Third, the cells in the follicle abnormally stick together as they are being shed, thus plugging the follicle. And, finally, the plugged-up follicle gets infected. Until recently, dermatologists didn’t know why the accelerated growth occurred, why these cells became excessively cohesive, or what caused the boost in oil production. But growing evidence suggests that elevated insulin and IGF-1 are directly responsible for the increased follicular skin growth, along with reductions in circulating blood levels of IGFBP-3. Remember that high-glycemic foods raise your blood level of IGF-1 while lowering IGFBP-3. This is why low-glycemic-load, high-protein diets are so effective in eliminating acne. They put the brakes on excessive follicular skin growth.

Besides causing increases in IGF-1 and reductions in IGFBP-3, elevated insulin levels from eating high-glycemic carbohydrates cause a rise in the male hormone testosterone. It is these increases in IGF-1 and testosterone that promote the discharge of oil. This means that insulin resistance caused by high-glycemic diets may be directly responsible for the first three steps in acne development. In the last five years, dietary intervention studies and a series of epidemiological studies from the Harvard School of Public Health have conclusively demonstrated that high-protein, low-glycemic diets like the Paleo Diet improve insulin metabolism and can help prevent acne. It is now safe to say that the Paleo Diet will improve your insulin metabolism—and if you have acne, this lifetime program of healthy eating will help it disappear.

As you can see, the Paleo Diet can be a very effective tool in fighting virtually all the diseases of metabolic syndrome.

—Malaya Kulujuk, a Baffin Island Eskimo

Many of the chronic illnesses that plague the Western world—the “diseases of civilization”—can be attributed to dietary missteps. Diet and disease are obviously linked. And when we stray from the Seven Keys of the Paleo Diet, which stood firm for 2.5 million years, we not only develop metabolic syndrome diseases, but also increase our susceptibility to a host of other diseases.

How can we know whether a particular food, or the lack of it, in our diet is actually the factor responsible for a particular disease—or the absence of it? If you have a milk allergy or lactose intolerance, the cause and effect of your symptoms are probably painfully clear. But it’s much harder—if not impossible—to foresee whether the pat of margarine (containing trans-fatty acids) you put on your toast yesterday morning will have anything to do with causing a heart attack forty years later.

Scientists and physicians use a variety of research procedures to determine whether diet and disease are linked, including dietary interventions, epidemiological studies, animal experiments, and cultured tissue studies. When the results of all four procedures are in agreement, it is quite likely that a certain food may cause a certain disease. However, in most cases the link between diet and disease is usually not this clear-cut; often, genetic susceptibility to disease further clouds the issue. In many of the diseases that we will be examining, the diet-disease connection has only been partially unraveled. Nonetheless, by adhering to the dietary guidelines of your Paleolithic ancestors, you will reduce your risk of developing these illnesses, and if you are currently suffering from one of these illnesses, your symptoms may improve with the Paleo Diet.

I’ve already talked about the metabolic syndrome diseases (type 2 diabetes, heart disease, hypertension, dyslipidemia, obesity, PCOS, myopia, acne, and breast, prostate, and colon cancers) and how they are linked to elevated levels of insulin in the bloodstream. But all of these diseases also have other known contributing dietary factors. For example, salt is connected to high blood pressure—but so is a lack of fresh fruits and vegetables. Too much omega 6 fat in your diet at the expense of omega 3 fat can also cause your blood pressure to rise. Even a low protein intake has been linked to rising blood pressure.

Breast, prostate, and colon cancers are known to develop more often in people who don’t eat enough fresh fruits and vegetables. Fruits and veggies hit cancer with a one-two punch: they’re excellent sources of antioxidant vitamins and minerals that may impede the cancer process, and they also contain a variety of special substances called “phytochemicals,” nutrients found in foods that are lethal to cancer cells. The study of most phytochemicals is fairly new; scientists are only beginning to understand how they work. But here are a few examples:

As is the case with high blood pressure, eating too many omega 6 and too few omega 3 fats further increases your risk of developing breast, prostate, and colon cancers.

We may not know precisely how dietary factors cause each and every metabolic syndrome disease, but one thing’s certain: when you adopt the Paleo Diet, you will be putting all known dietary factors on your side to prevent these illnesses.

The number one killer in the United States is cardiovascular disease. A staggering 35 percent of all deaths in this country result from heart attacks, stroke, high blood pressure, and other illnesses of the heart and blood vessels. Cardiovascular disease, like cancer, is a complex illness, and no single dietary element is solely responsible. However, once again, by following the nutritional principles of humanity’s original diet, you will put the odds in your favor of not developing this deadly disease.

Good fats are what doctors call “cardioprotective.” They protect the heart and the blood vessels from disease. With the Paleo Diet—unlike the average American diet—at least half of your fats are healthful monounsaturated fats. The other half is evenly split between saturated and polyunsaturated fats. There are no synthetic trans fats. And the crucial omega 6 to omega 3 fat ratio is about 2 to 1—which greatly reduces your risk of dying from heart disease.

Monounsaturated fats reduce your overall risk of heart disease by lowering your level of total cholesterol—but not your beneficial HDL cholesterol—in the blood. These healthful fats—found in abundance in the Paleo Diet—also help prevent LDL cholesterol from oxidizing (breaking down) and contributing to the artery-clogging process. Monounsaturated fats also may reduce your risk of breast cancer.

I’ve already talked about the beneficial effects of omega 3 fats on insulin metabolism and how they lower blood triglycerides. Omega 3 fats are also exceptionally potent agents in preventing the irregular heartbeats that can make a heart attack fatal. They help prevent blood clotting and ease tension in clogged arteries as well.

In a landmark dietary intervention study, French physicians Serg Renaud and Michel de Lorgeril evaluated the effect of a diet rich in omega 3 fats in 600 patients who had previously survived a heart attack. In this investigation, known as the Lyon Diet Heart Study, half of the patients were assigned to the American Heart Association reduced-fat diet, in which 30 percent of calories come from fat. The rest followed a 35 percent fat traditional Mediterranean diet that was rich in omega 3 and monounsaturated fats and fruits and vegetables.

The results were striking: compared to the patients who followed the American Heart Association Diet, those who were on the Mediterranean diet had a 76 percent lower risk of dying from another heart attack, a stroke, or another cardiovascular disease. This remarkable protection from heart disease can be yours, too. Like the Mediterranean diet, humankind’s original diet is also high in cardioprotective omega 3 fats, fiber, monounsaturated fats, and the beneficial phytochemicals and antioxidant vitamins that are found in fruits and vegetables.

The average cereal-based, salt-laden, cheese-filled American diet—which is nearly devoid of fresh fruits and vegetables—tilts your body’s acid-base balance in favor of acid. As we discussed earlier, grains, cheeses, meats, and salty foods yield a net acid load to the kidneys, while fruits and vegetables always generate an alkaline load. An overload of acid foods—at the expense of alkaline foods—can cause numerous health problems, particularly as you age and your kidneys become less adept at handling dietary acid.