Effects of daily black walnut consumption on blood lipid levels

Abstract

English walnuts (EW) have been marketed for cardiovascular benefits including favorable changes in blood lipid profile, attributed to their fatty acid content. In contrast, black walnuts (BW) have not yet been studied for such benefits. The purpose of our research was to compare black versus English walnut effects on blood lipid levels. Thirty‐six subjects (female=20, male=16), ages 62±12 years, were recruited and randomly assigned to either EW or BW groups (18 per group). Venous blood lipid levels were analyzed following a 12‐hour fast before and after 28‐30 days of walnut consumption. Subjects consumed 30 g of provided pre‐weighed nuts daily with their usual diet. They reported usual food intake and medications and were weighed before and after each nut treatment. After a 12‐week washout period, 29 subjects (female=16, male=13) crossed over and consumed the other type of walnut for 28‐30 days (BW=13, EW=16). Response to EW consumption in both genders was largely consistent with previous studies. A significant reduction in LDL, HDL and total cholesterol was found in men who consumed BW; however, a significant increase in total cholesterol, HDL, and LDL was found in women who consumed BW. Consumption of either walnut type did not result in weight gain. Walnuts may benefit health, but black walnut benefits may be affected by gender. This research was funded by UW‐L internal grants and BW were supplied by Hammons Products Co.