A new randomized controlled trial increases our understanding of why regular nut consumption is associated with lower rates of cardiovascular disease and deaths. The Walnuts and Healthy Aging study, with study groups in both Spain and the U.S., randomized 708 healthy adults ages 63 go 79 to either eat a walnut-free diet or consume 30 to 60 grams of walnuts daily (to make up about 15 percent of daily calorie intake) for two years. Compliance, tolerance, medication changes, and body weight were recorded every two months. Blood tests at the start and end of the study period measured fasting blood sugar, cholesterol, and triglyceride levels.
The walnut diet decreased total cholesterol, low-density lipoprotein (LDL) cholesterol, and intermediate-density lipoprotein cholesterol significantly. High-density lipoprotein (HDL, “good”) cholesterol, triglycerides and glucose concentrations, as well as blood pressure were favorably affected. Neither group of participants gained weight. In the full original study, there were no significant between-group differences in the development or reversion of metabolic syndrome. It should be noted that the average cholesterol levels of all participants were normal at the start of the study, in part due to the fact that 32 percent were taking cholesterol-lowering statins.