Two patients follow identical diets cutting down on their saturated fats. One patient's cholesterol level plunges 123 milligrams per deciliter. The other's dips down only 1 mg/dL.Why? Because cholesterol, like life, isn't fair. Different people respond in different ways to saturated fats. Those who get the most benefit from cholesterol-lowering diets are probably those most sensitive to saturated fats.

This recent finding by CHN Director Dr. Scott Grundy may ease a patient's frustration when diet doesn't make a dent in his cholesterol level. It also can help physicians decide whether they can adequately treat patients with diet or also need to prescribe medication. "If a person goes on a diet that is low in saturated fat and if he is sensitive, his cholesterol will come down a lot," said Grundy. "If he is not sensitive, the cholesterol won't come down much." In four metabolic studies, Grundy observed a wide range of responses when unsaturated fatty acids were substituted for saturated fats. Previous studies had shown a narrow and fairly predictable range of responses to cholesterol.

"Humans are more sensitive to the types of fatty acids in the diet than they are to cholesterol in the diet," concluded Grundy. He compared the fat reactions to the way salt affects people with high blood pressure or hypertension. "Some people can lower their blood pressure by cutting down on salt and losing weight--for others, this has no effect whatsoever," Grundy said. "They would still have high blood pressure if they were very thin and didn't eat salt."

He also observed that people who responded best to diet tended to be at the high-risk 240-300 mg/dL total cholesterol level. Grundy and Dr. Gloria Lena Vega, an assistant professor of clinical nutrition at UT Southwestern, published their study in the May issue of the American Journal of Clinical Nutrition. Their follow-up study on fat sensitivity will be funded under a National Institutes of Health grant.