Reducing Saturated Fat? Watch What Carbs You Substitute

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Are refined carbohydrates worse than saturated fat? Thats the provocative headline of a recent American Journal of Clinical Nutrition editorial commenting on a large new Danish study of diet and heart-attack risk. Author Frank B. Hu, MD, PhD, of the Harvard School of Public Health, explains how, for decades, the diet-heart paradigm thats been the driving force behind dietary recommendations has emphasized the heart-health dangers of saturated fat and cholesterol. Thats led to a decrease in Americans total and saturated fat intake, while carbohydrate consumption went up. Until recently, Dr. Hu adds, the role of carbohydrates in cardiovascular disease has received scant attention.But now that paradigm is being challenged by new research that suggests reducing saturated fat by itself isnt the key to preventing heart disease (see the May Healthletter). Replacing saturated fat with polyunsaturated fat, such as liquid vegetable oil, is one strategy that seems to have hearthealth benefits (see the July Healthletter). Too many Americans, however, have replaced the saturated-fat calories in their diets with refined carbohydrates-which appear to have heart risks of their own.The Danish researchers report that replacing saturated fats with foods such as baked potatoes and white bread is actually associated with a significantly higher risk of heart attack, while substituting foods such as whole grains and vegetables is linked to slightly lower risk. Marianne U. Jakobsen, MSc, PhD, of Aarhus University Hospital, and colleagues followed 53,644 healthy adults for an average 12 years, during which 1,943 subjects suffered heart attacks. Those who substituted refined carbohydrates, as measured by a foods glycemic index (GI), for saturated fats were 33% more likely to have a heart attack. People who picked low-GI carbohydrates in lieu of saturated fat, on the other hand, were at slightly lower risk.But dont worry too much about glycemic index. The most practical way to reduce your heart-disease risk from carbohydrates is to eat less-refined foods, non-starchy vegetables, fruit and legumes, Jakobsen and colleagues advise.Whole grains, especially those high in soluble fiber-such as barley, oats and rye-are also better choices than highly processed carbohydrate sources such as white bread. When the healthful outer layers of a grain-the bran and germ-are stripped away by processing, not only are fiber and micronutrients lost, but the remaining grain particles are smaller and more exposed. That makes them faster to digest, leading to the rush of blood sugar thats been associated with greater risk of diabetes and heart disease.Clearly, diets high in either saturated fat or refined carbohydrates are not suitable for heart-disease prevention, Dr. Hu concludes. However, refined carbohydrates are likely to cause even greater metabolic damage than saturated fat in a predominantly sedentary and overweight population.Alice H. Lichtenstein, DSc, director of Tufts HNRCA Cardiovascular Nutrition Laboratory, advises, Since 2000 the major dietary guidelines intended to prevent or treat heart disease have advocated a moderate fat diet that is low in saturated fat. That translates to displacing saturated fat with polyunsaturated fat. The most recent research findings confirm the wisdom of this recommendation and suggest that we should not focus on a single diet component but the whole diet pattern. When the intake of one component of the diet goes down, another goes up. We need to be mindful of both sides of the equation. In this case, that translates to substituting one type of fat for another, not carbohdyrate, especially refined carbohydrate.TO LEARN MORE: American Journal of Clinical Nutrition, June 2010; abstract at www. ajcn.org/cgi/content/abstract/91/6/1764

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