After smoking, a high-fat diet is the second most lethal habit. According to a report in the Journal of the American Medical Association, smoking causes 400,000 deaths a year. High-fat diet causes 300,000. Several more highly publicized social evils are comparatively small problems: alcohol (100,000 deaths), guns (35,000), auto accidents (25,000), and drug abuse (20,000). These statistics in no way minimize the tragedies of alcoholism, murder, or drug addiction. But they provide perspective on what’s really killing us. Few people cringe when Aunt Mary serves up large slices of banana cream pie a la mode, but from a public health perspective, she might as well be offering heroin. If this sounds a bit extreme, consider the dangers of dietary fat, and judge for yourself:
Obesity. As weight increases above a body mass index of about 28, so does risk of premature death. Obesity is a risk factor for heart disease, several cancers, hypertension, diabetes, arthritis, and multiple sclerosis. It is a problem only in countries with high-fat diets. In addition to being hazardous to health, obesity is also an economic handicap. Obese people earn less money than those who are slimmer.
Heart Disease. The nation’s leading cause of death, heart disease kills 720,000 Americans a year, most as a result of heart attacks. About one American in four suffers some form of heart disease. Heart disease results from a process called atherosclerosis, which is directly linked to dietary fat. Fatty foods are high in cholesterol and free radicals. Free radicals are oxygen molecules that have lost an electron, and become highly reactive. As they circulate in the blood, they snatch electrons away from other molecules, sometimes grabbing them from the cells that line artery walls. The microscopic injuries that free radicals inflict begin a decades-long process that eventually narrows the arteries with cholesterol-rich deposits called plaques. Sometimes plaques rupture, spilling their contents into the blood. If a plaque ruptures in one of the coronary arteries that nourish the heart, its debris can cause completely blockage. Without food and oxygen to nourish its hard-working cells, part of the heart dies. That’s a heart attack. Although heart disease generally strikes after 40 in men and after menopause in women, atherosclerotic arterial damage begins in childhood. A study by Jack Strong, M.D., chair of the pathology department at Louisiana State University Medical Center in New Orleans, analyzed autopsies of 1,532 teenagers who died in accidents. One hundred percent showed atherosclerotic plaques in their aortas, the body’s largest artery.
Stroke. Stroke is the nation’s third leading cause of death, claiming 144,000 lives a year. There are two major types of stroke, one caused by bleeding in the brain (hemorrhagic), the other by blockage of an artery there (ischemic). About 75 percent of strokes are ischemic, and the vast majority of ischemic strokes are caused by cerebral thrombosis, blockage of a brain artery in a process similar to heart attack, involving fat-related atherosclerosis and plaque rupture.
Cancer. A high-fat diet does not contribute to all cancers, but many studies have linked it to several, notably colon and breast cancer, which together account for 100,000 deaths a year. Other studies suggest that a high-fat diet may play a role in causing cancers of the prostate (42,000 deaths annually), pancreas (28,000), and possibly lung cancer in nonsmokers (30,000), and malignant melanoma (7,300). The American Cancer Society urges everyone to eat less fat. Dietary fat contributes to cancer risk because of free radicals. A high-fat diet increases the number of these molecules in the blood. If they don’t snatch electrons from artery walls, causing heart attack or stroke, they may grab them from the chromosomes that contain our genes. Chromosomes can often repair themselves, but if they continue to sustain significant damage for many years, cellular repair mechanisms may become overwhelmed, resulting in cancer.
High Blood Pressure (Hypertension). Hypertension is a major risk factor for heart disease and stroke. High-fat diet contributes to this condition because it adds extra pounds. As weight increases, the heart must work harder to pump blood through all the extra tissue. As the heart’s effort increases, so does blood pressure.
Diabetes. Diabetes contributes to an estimated 250,000 deaths a year. It involves an inability to metabolize blood sugar because of problems with the pancreatic hormone, insulin. In Type 1 diabetes, the pancreas stops producing insulin. In the vastly more common Type 2 diabetes, typically associated with obesity, insulin production may be normal, but obesity prevents the body from using it efficiently.
Osteoarthritis. Dietary fat contributes to the most common form of arthritis, osteoarthritis, because excess weight subjects the major joints to extra wear and tear.
Rheumatoid Arthritis. A high-fat diet also appears to increase risk of rheumatoid arthritis (RA), the most serious and potentially crippling form of joint disease. Several studies suggest that a low-fat diet relieves RA symptoms.
Multiple Sclerosis. For the last 50 years, Roy Swank, M.D., a professor emeritus of neurology at the Oregon Health Sciences University in Portland, has amassed evidence that a high-fat diet is a key risk factor for multiple sclerosis (MS), which causes an enormous number of symptoms from blurred vision to paralysis. His studies show that a low-fat diet minimizes MS symptoms.
“Most Americans who have chronic health problems,” says William Castelli, M.D., longtime director of the Framingham Heart Study, the nation’s oldest ongoing research program into the causes of heart disease, “would not have them if they ate a low-fat diet.”