Don't Replace All Saturated Fat with Carbohydrates

There's no question that saturated fats in the diet increase your risk of developing cardiovascular disease. But if you reduce dietary fat intake, what is the best replacement for the abandoned fat calories - carbohydrates or protein?

The usual recommendation for a heart healthy diet contains about 30 percent of calories as fat, 15 to 20 percent of calories as protein, and the remaining 50 percent or so of calories as carbohydrates. Results of the OmniHeart study suggest a better dietary solution.

The researchers compared the effects of three different diets on coronary risk factors. All were low in saturated fat, cholesterol, and sodium. One diet was high in carbohydrates; the other two replaced about 10 percent of the carbohydrates with either protein or monounsaturated fats. The added proteins came largely from plant sources like beans, nuts, seeds, and some grains. Olive and canola oils, along with certain nuts and seeds, were the major components added in the monounsaturated-enriched diet.

Each of the 164 healthy adult participants ate all of their foods from one of the three diets for 6 weeks. After a break for about 2 to 4 weeks, they started a 6-week period with one of the other diets, until they all had eaten all three diets.

While all three diets lowered cholesterol levels and blood pressure compared to diets containing more saturated fat and sodium, the two diets that replaced 10 percent of the carbohydrates reduced these risk factors even more than the one containing more carbohydrates.

The authors of the study state that low-carbohydrate diets, like the Atkins diet and its imitators, are unhealthy because they replace carbohydrates with high saturated fat and animal proteins.

These findings support the need to avoid saturated fats and emphasize the benefits of monounsaturated fats and plant-based proteins.