The role of dietary fats in plant-based diets.

In the United States, the notion that low-fat, high-carbohydrate diets are essential for health has grown into an obsession, driven largely by an effort to reduce heart disease and, more recently, certain types of cancer. We know that saturated fatty acids are more closely associated with risk factors for heart disease than are unsaturated fatty acids. Many people believe that plant-based diets are healthy because they are low in fat. However, plant-based diets are not necessarily low-fat. In true plant-based diets, unsaturated fatty acids predominate, whereas saturated fatty acids come largely from animal sources such as dairy products and eggs. Plant-based diets include foods that contain fats, such as nuts and seeds and oils from grains and seeds. The fats in these foods are not associated with increased risk for heart disease. In addition, for people with insulin resistance, higher-fat diets protect against the heart disease risk factors of low HDL-cholesterol concentration, hypertriglyceridemia, hyperglycemia, and hyperinsulinemia. Because humans can synthesize fat from dietary carbohydrate, and because our adipose stores and circulating fatty acids reflect dietary intake, scientists understand the relations between the amounts and types of dietary fats and the types of fats found in body fat depots. Consuming dietary fats that are not associated with increased risk of disease can be a part of a healthful diet.