Doctors usually advise patients with high cholesterol to eat a Mediterranean diet, which is low in animal fats, high in fruits, vegetables and olive oil (monounsaturated fat). Recent studies show that adding walnuts to your diet may reduce cholesterol levels further. Studies show that walnut extracts, called polyphenolic compounds, prevent the oxidation of cholesterol. Oxidized cholesterol contributes to plaques that cause heart disease and strokes.
A study from Spain compared two diets--one a normal Mediterranean diet, another the same diet, but with walnuts substituted for some of the olive oil and other high fat foods. The diet included 11 walnuts a day, replacing 35% of the fat calories as compared to the normal Mediterranean diet, for six weeks. The participants in this study were 55 men and women, average age 56, who were being treated for high cholesterol. At the end of the study, the walnut group had significantly lower total cholesterol as well as lower low-density lipoprotein levels (LDL, the bad cholesterol) as compared to the regular Mediterranean diet. The researchers concluded 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 high cholesterol.
In another study from Japan, researchers compared a diet with 12.5% of its energy from walnuts to a control diet. The walnuts were substituted for other high-fat foods like meat and fat. The results were similar to the Barcelona study. Both total cholesterol and LDL levels were significantly lower among the walnut-eaters than those in the control diet. Substituting walnuts for some of the fat in a normal diet reduces both total cholesterol and LDL levels.
The trick is to eat walnuts INSTEAD of other fats. Cutting back on other fats to compensate for the walnuts will not result in weight gain.
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Annals of Internal Medicine, 2000, Vol. 132, No. 7 pp. 538-546;
Journal of Nutrition, 2000, Vol. 132, No. 2, pp. 171-176