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 The Latest In . . . OBESITY Meat-Eaters Gain Weight A new study confirms that meat-eating encourages weight gain. Researchers from the American Cancer Society studied 79,236 young and middle-aged men and women, measuring their diets in 1982 and again in 1992. Those who ate more than three servings of meat per week were much more likely to gain weight as the years went by, compared to those who tended to avoid meat. The more vegetables the participants ate, the more resistant they were to weight gain. Previous studies have shown that people who switch to a vegetarian diet become, on average, about 10 percent leaner. Dr. Dean Ornish’s study using vegetarian diets to reverse heart disease also yielded an impressive 22-pound average weight loss per person in the first year. Dr. Andrew Nicholson’s diabetes study found that a vegan diet knocked off an average of 16 pounds in 12 weeks. Part of the problem with meats is their fat content; even skinless chicken breast is 20 percent fat. But meats are also very high in protein and have no complex carbohydrate or fiber. High-protein, low-carbohydrate diets tend to inactivate thyroid hormone, which, in turn, may lead to weight gain. Heart Damage from Fen-Phen The New England Journal of Medicine reported in August that the popular weight-loss drug combination, fenfluramine and phentermine, known as fen-phen, caused serious heart troubles in 24 women. Nine similar reports were already on file with the Food and Drug Administration. Each woman had a thickening of the heart valves, which forces the heart to work harder to pump blood. Five of the women needed surgery for their damaged valves, and eight developed pulmonary hypertension. The women had used the drug for an average of 12 months. Fenfluramine and dexfenfluramine were pulled off the market September 15. Kahn HS, Tatham LM, Rodriguez C, Calle EE, Thun MJ, Health CW. Stable behaviors associated with adults’ 10-year change in body mass index and likelihood of gain at the waist. Am J Publ Health 1997;87:747-54. SUPPLEMENTS Caution on DHEA DHEA has been widely promoted as the elixir of youth, based on animal experiments in the 1970s and 1980s that suggested that it might be an immune enhancer. In humans, it may have very different effects. DHEA, or dehydroepiandrosterone, is sold at health food stores and exists naturally in the blood as a precursor to testosterone and estrogens. Joanne Dorgan, Ph.D., of the National Cancer Institute compared 71 postmenopausal women with breast cancer to other women who did not have cancer. By checking blood serum that had been stored at the Breast Cancer Serum Bank in Columbia, Missouri, before the cancer was found, she discovered that the more DHEA there was in the women’s blood, the higher their risk of breast cancer. Those with the highest DHEA levels had four times the risk compared to those with the lowest levels. Dorgan JF, Stanczyk FZ, Longcope C, et al. Relationship of serum dehydroepiandrosterone (DHEA), DHEA sulfate, and 5-androstene-3 beta, 17 beta-diol to risk of breast cancer in postmenopausal women. Cancer Epidemiology, Biomarkers, and Prevention 1997;6:177-81. BONE HEALTH Milk Does Not Protect Bones Milk consumption does not protect against fractures, according to new data from the Harvard Nurses’ Study. The study recruited a group of 77,761 women who were between 34 and 59 years of age when the study began in 1980, and followed them for the next 12 years. Those who drank three or more glasses of milk per day had no reduction at all in the risk of hip or arm fractures compared to those who drank little or no milk, even after adjustment for weight, menopausal status, smoking, and alcohol use. In fact, the fracture rates were slightly higher for those who consumed this much milk compared to those who drank little or no milk. The findings resonate with international comparisons that show that fracture rates in Scandinavia and other areas where dairy products are commonly consumed are actually much higher, not lower, than in Asia and other areas where milk products are rarely used. The differences are the result of two other factors. First, in international studies, genetics play a role, with white women at higher risk than other groups. Second, other animal protein greatly increases calcium loss via the kidneys. Since dairy cattle are slaughtered when their productivity declines, usually at four years of age in the U.S., countries where milk is consumed tend to have plenty of hamburger on grocery shelves. It may be that meat consumption is what leads to the fractures. Salt, caffeine, tobacco, and a sedentary lifestyle also contribute to calcium losses. Feskanich D, Willett WC, Stampfer MJ, Colditz GA. Milk, dietary calcium, and bone fractures in women: a 12-year prospective study. Am J Publ Health 1997;87:992-7. CANCER War on Cancer a Stalemate Eleven years ago, John Bailar III, M.D., Ph.D., published the study no one wanted to see. After painstakingly going through cancer death rates, he was forced to conclude that the War on Cancer was a qualified failure. As editor in chief of the Journal of the National Cancer Institute, Bailar was in a position to know. Cancer death rates were high and climbing. To win the war, he wrote, we needed to switch our research emphasis from treatment to prevention. The National Cancer Institute all but ignored his advice and stuck to its goal of cutting the cancer death rate in half by the year 2000. Bailar’s new assessment, published in the New England Journal of Medicine, is nearly as grim as the first. After peaking in 1991, overall cancer death rates among men declined only slightly from 1991 to 1994. Rates for women have stayed near their 1991 peak. Breast cancer rates continue to increase for women over 55 but have declined for younger women. Lung cancer rates have skyrocketed for older women but have changed little for men and younger women. Colon cancer rates remain among the highest of any cancer site but have steadily declined since 1970. Bailar concludes, “A national commitment to the prevention of cancer, largely replacing reliance on hopes for universal cures, is now the way to go.” More Evidence on Fat and Breast Cancer A new study in a group of women in Italy showed that saturated fat (the type of fat found mainly in meats and dairy products) was the element of the diet most predictive of breast cancer risk. Alcohol was the second biggest culprit. In a separate report, Ernst L. Wynder, M.D., of the American Health Foundation weighed the evidence on fat and breast cancer for the Journal of the National Cancer Institute, finding that the more fat women eat, the higher their risk of breast cancer. Those studies that have failed to find this association, Wynder concludes, suffered from methodological problems. Bailar JC, Gornik HL. Cancer undefeated. N Engl J Med 1997;336:1569-74. BACK PAIN Tracing the Causes A major cause of back pain may be nerves that have grown deeply into degenerating discs. A disc is a leathery cushion that separates one vertebra from another. Normally, its tough outer sheath covers a soft inner core. If the sheath deteriorates, the interior tissues can herniate outward, pushing on a nerve root or even on the spinal cord itself. A break in the disc can also stimulate inflammation, irritating the nerves and causing the back muscles to tighten up in response. Sometimes, however, people have pain without any signs of nerve compression or irritation. The cause may be nerves that have grown into the damaged discs. Normally, pain nerves do not enter past the outer surface of the disc. But researchers examining specimens removed at surgery found that, in patients with a history of back pain, pain nerves had grown well into degenerated discs, following blood vessels that grow as part of the repair process. What causes the degeneration in the first place? For many people, the problem is clogged arteries. The lumbar arteries that nourish the spine are among the first to develop atherosclerotic plaques. Advanced blockages are present in some people—perhaps as many as 10 percent—by age 20. A blocked lumbar artery means that the vertebrae and discs are cut off from their normal supply line for oxygen and nutrients. They also have more difficulty repairing damage and eliminating cellular waste products that can irritate nerve endings. In autopsy studies, people who had a history of back pain have been found to have an average of two completely blocked arteries to the lower back and at least one more that was narrowed but not yet blocked. People who had not had back pain had fewer blockages. A low-fat, vegan diet, along with regular exercise, avoiding smoking, and reducing stress, can prevent and even reverse artery blockages elsewhere in the body. Perhaps it can also help prevent or even treat back pain. Freemont AJ, Peacock TE, Goupille P, Hoyland JA, O’Brien J, Jayson MIV.
Nerve ingrowth into diseased intervertebral disc in chronic back pain. Lancet
1997;350:178-81. |
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