Eating walnuts lowers serum cholesterol

Townsend Letter for Doctors and Patients,  Jan, 2001  by Alan R. Gaby

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Fifty-five men and women (mean age, 56 years) with hypercholesterolemia were randomly assigned to a cholesterol-lowering Mediterranean diet or a diet of similar energy and fat content in which walnuts replaced approximately 35% of the energy obtained from monounsaturated fat. After six weeks, the patients consumed the other diet for an additional six weeks. On the Mediterranean diet olive oil was used and no nuts were allowed. On the walnut diet walnuts partially replaced olive oil and other fatty foods. The amount of walnuts consumed was 41-56 g/day (8-11 walnuts per day), which contributed about 18% of total energy and 35% of total fat. Forty-nine patients completed the trial. Compared with the Mediterranean diet, the walnut diet produced mean changes of -4.1% in total cholesterol level, -5.9% in LDL cholesterol level, and -6.2% in lipoprotein(a) level. The mean differences in the changes in serum lipid levels were -10.8 mg/dl for total cholesterol (p [less than] 0.001), -11.2 mg/dl for LDL cholesterol (p [less than] 0.001), and -0.021 g/l for lipoprotein(a) (p = 0.042).

Comment: These results indicate that substituting walnuts for part of the monounsaturated fat in a cholesterol-lowering Mediterranean diet further reduced total and LDL cholesterol levels in men and women with hypercholesterolemia. Many people shy away from eating nuts, because of their high fat content. However, several intervention studies have shown that eating various types of nuts can reduce serum cholesterol levels. Moreover, epidemiological studies have shown that consumption of nuts is associated with a reduced risk of developing heart disease. The apparent beneficial effect of nuts may be due to their content of essential fatty acids, fiber, or other cardioprotective nutrients such as arginine. Because the fatty acids in nuts can spontaneously oxidize to form damaging free radicals, nuts should be stored in an air-tight container in the refrigerator or freezer.

Zambon D, et al. Substituting walnuts for monounsaturated fat improves the serum lipid profile of hypercholesterolemic men and women. A randomized crossover trial. Ann intern Med 2000;132:538-546.

COPYRIGHT 2001 The Townsend Letter Group
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