U.S.
Food and Drug Administration
FDA Consumer magazine
January-February 2003
Table of Contents
Healthy people should eat omega-3 fatty acids from fish and plant sources to protect their hearts, according to updated recommendations by the American Heart Association.
"Omega-3 fatty acids are not just good fats; they affect heart health in positive ways," says Penny Kris-Etherton, Ph.D., R.D., lead author of a report published in the Nov. 18, 2002, issue of Circulation: Journal of the American Heart Association.
Omega-3 fatty acids make the blood less likely to form clots that cause heart attack, and they protect against irregular heartbeats that cause sudden cardiac death, the report says.
Kris-Etherton and colleagues examined the health benefits of omega-3 fatty acids in the context of cardiovascular disease (CVD) risk reduction and considered the recent Environmental Protection Agency and Food and Drug Administration guidance about the presence of contaminants in certain species of fish.
Since 2000, the American Heart Association's dietary guidelines have recommended that healthy adults eat at least two servings of fish per week, particularly fish such as mackerel, lake trout, herring, sardines, albacore tuna and salmon. These fish contain two omega-3 fatty acids--eicosapentaenoic and docosahexaenoic acids (EPA and DHA). A third kind, alpha-linolenic acid, is less potent and comes from plants, including tofu and other forms of soybeans, and nuts and seeds and their oils, including canola, walnut and flaxseed oils.
People who have elevated triglycerides may need two grams to four grams of EPA and DHA per day provided as a supplement, according to the new guidelines. Those taking more than three grams of omega-3 fatty acids from supplements should do so only under a physician's care. The FDA has noted that high intakes could cause excessive bleeding in some people.
The mechanisms responsible for omega-3 fatty acids' reduction of CVD risk are still being studied, and include decreases in triglyceride levels and blood clots, lower risk of sudden death, improved arterial health, and lower blood pressure.
Transplanted hearts stayed healthier in people who took a cholesterol-lowering drug, according to a new, eight-year study.
Researchers found that the survival rate for transplant patients who received early simvastatin treatment was 88.6 percent compared with 59.5 percent of patients who didn't start simvastatin treatment until four years after transplant, says Klaus Wenke, M.D., lead author of the paper and assistant professor in the division of cardiac surgery at Munich-Bogenhausen, Munich, Germany. Results of the study were published in the Dec. 6, 2002, rapid access issue of Circulation: Journal of the American Heart Association.
The authors also studied the effects of simvastatin on the development of coronary artery thickening called transplant vasculopathy, which is a major long-term complication of heart transplantation. Early simvastatin treatment cut in half the incidence of vessel thickening as measured by angiography, which probably explained the improved survival rate. After eight years, 54.7 percent of the patients in the untreated group had developed transplant vasculopathy, compared to just 24.4 percent of patients in the simvastatin group.
Wenke and colleagues studied 72 patients who had heart transplants beginning in 1991. All patients were put on a strict low-cholesterol diet after surgery. Thirty-five patients started daily simvastatin treatment four days after transplant, while 37 remained on dietary therapy alone. After four years, the results in the simvastatin group were "significantly better," so all patients were offered simvastatin, says Wenke.
Benefits of simvastatin may be due not only to its ability to reduce cholesterol, but also to its ability to reduce the growth of smooth muscle cells (cells in the vessel wall that contribute to vessel thickening).
While day-to-day physical activities such as walking, housework and shopping may be good for your heart, they don't do much for your bones, researchers at Johns Hopkins University in Baltimore say.
Their study, published in the November 2002 issue of the Journal of Internal Medicine, found that neither light-intensity activities nor aerobic fitness level contributed to bone health, contrasting previous studies suggesting that aerobics could play a role. Having a few extra pounds, however, was a help. Among a group of older adults studied, those with greater muscle strength and higher body fat, especially in the abdomen, had higher bone mineral densities.
"Carrying extra body weight increases the forces on bone, strengthening it, though the largest forces come from more vigorous exercise rather than routine low-intensity physical activity," says lead author Kerry J. Stewart, Ed.D., director of clinical exercise physiology at Johns Hopkins. "In our study of typical older people, who unfortunately do not participate in regular vigorous exercise, daily activities and low-intensity exercise like walking appeared to be relatively ineffective for preventing aging-related bone loss."
The researchers do not advocate gaining weight to fight osteoporosis.
"Paradoxically, a high percentage of abdominal fat seems to increase bone mineral density," Stewart says, "but it also increases the risk of heart disease, high blood pressure and diabetes, and worsens the symptoms of chronic conditions such as knee arthritis."
Stewart and colleagues studied 84 adults (38 men and 46 women) ages 55 to 75 with higher than normal blood pressure but who were otherwise healthy. They were not exercising regularly, defined as moderate- or high-intensity exercise for 30 minutes a day, three or more times per week.
Researchers used X-rays to measure the participants' bone mineral density in the total skeleton, lower spine and hip, and calculated abdominal fat with magnetic resonance imaging. They weighed each participant and had each do a treadmill exercise test and a series of weight-training exercises to measure aerobic fitness and muscle strength. In addition, the individuals completed a physical activity questionnaire.
The study found that aerobic exercise was not associated with bone mineral density but abdominal fat was. Muscle strength was associated with bone mineral density at some, but not all, sites tested.