Q: For a number of years my family has been using safflower oil in our salads and cooking in order to help lower our cholesterol levels. We are confused, because magazine articles now tell that olive oil is a better choice. Should we switch to olive oil instead of safflower oil?
A: The standard dietary recommendations to lower blood cholesterol have included a reduction in total fat intake to less than 30 percent of calories, restriction of dietary cholesterol to less than 300 milligrams per day and replacement of saturated fats with polyunsaturated fats such as safflower or corn oil. These measures do lower the total and LDL (bad) cholesterol. But diets rich in these polyunsaturated fats also tend to lower the good (HDL) cholesterol level.
Several studies have shown that the monounsaturated fatty acids found in olive and canola oils are as effective as polyunsaturated fatty acids in lowering the LDL cholesterol level and have the added benefit of not lowering HDL.
Moreover, recent studies have provided yet another reason for choosing monounsaturated rather than polyunsaturated oils. Scientists now believe that the first step in the development of atherosclerosis (fatty deposits that eventually narrow coronary and other arteries) is the deposit of chemically modified LDL in certain cells called macrophages in the arterial wall. LDL is chemically modified by oxidation of its unsaturated fatty acids by molecules called free radicals, formed during normal ' metabolism.
Findings suggest that replacing the dietary saturated fats with monounsaturated oils, rather than polyunsaturated ones, may be more effective in the prevention of atherosclerosis.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine and associate dean for faculty affairs at the school.