The Hopkins team found that shifting about 10 percent of calories from carbohydrate to either protein-rich foods, mostly from plant sources, or to monounsaturated fats, contained in olive and canola oil, provided a major benefit to the heart.
"Our study provides strong evidence that replacing some carbohydrate with either protein or monounsaturated fat has important health benefits," says internist Lawrence Appel, M.D., M.P.H., a professor of medicine at the Johns Hopkins School of Medicine and lead author of the study. "There is already agreement that reducing saturated fat lowers risk for heart disease, but the question of which macronutrient to emphasize has been controversial."
Appel makes clear that his study does not support extremely high-saturated-fat, low-carbohydrate diets such as the Atkins diet, which he says is not a healthy diet plan.
The study, called the Optimal Macronutrient Intake Trial to Prevent Heart Disease (OmniHeart), evaluated three healthy diets that differed mainly in the amount of macronutrients - protein, fat and carbohydrate - that provide calories used for energy in the body. All three diets were low in saturated fat, cholesterol and sodium, and rich in fruits, vegetables, fiber, potassium and other minerals. However, one diet was a traditional healthy diet, rich in carbohydrate, while in the other two diets approximately 10 percent of its calories from carbohydrate were replaced with either monounsaturated fat or protein. In the protein-rich diet, about half came from plants.
"All three diets reduced overall heart disease risk, lowering blood pressure and improving cholesterol levels,"
Contact: David March or John Sales
Johns Hopkins Medical Institutions