Despite widespread consensus that a reduced intake of saturated fat lowers cardiovascular disease (CVD) risk, the optimal type of macronutrient (protein, unsaturated fat, or carbohydrate) that should replace saturated fat is uncertain, according to background information in the article. Two major goals of dietary recommendations are to lower blood pressure and improve serum lipids, two of the primary determinants of CVD risk.
Lawrence J. Appel, M.D., M.P.H., of Johns Hopkins University, Baltimore, and colleagues with the Optimal Macronutrient Intake Trial to Prevent Heart Disease (OmniHeart) study compared the effects on blood pressure and serum lipids of three healthful diets: a carbohydrate-rich diet, similar to the DASH diet (Dietary Approaches to Stop Hypertension); a diet rich in protein, approximately half from plant sources; and a diet rich in unsaturated fat, predominantly monounsaturated fat. Each diet was reduced in saturated fat, cholesterol, and sodium and rich in fruits, vegetables, fiber, potassium, and other minerals at recommended levels. The randomized feeding study involved 164 adults with prehypertension or stage 1 hypertension. Participants ate each diet for 6 weeks and body weight was kept constant. The study was conducted from April 2003 to June 2005.
The researchers found that blood pressure, low-density lipoprotein cholesterol, and estimated coronary heart disease risk were lower on each diet in comparison to baseline. "In OmniHeart, [compared to a carbohydrate-rich diet], a diet that partially replaced carbohydrates with protein, about half fr
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