The research supporting the role that walnuts can play in heart health began with a Loma Linda University study, showing walnuts may lower total and LDL cholesterol in men by as much as 12 percent and 16 percent, respectively.² In this eight-week randomized, crossover trial, 18 healthy men (ages 21-43) were assigned to a cholesterol-lowering diet that did not include nuts or a cholesterol-lowering diet that included walnuts. All food was provided by the researchers and the walnut diet contained three servings (equivalent to 3 ounces) of walnuts per day.

A systematic review from the Harvard T.H. Chan School of Public Health examined 25 years of evidence for the role of walnut consumption on cardiovascular risk factors, including cholesterol, triglycerides, blood pressure, and weight.³ A meta-analysis was done on 26 randomized controlled trials representing 1059 individuals (ages 22-75), including those with a variety of conditions such as high cholesterol, type 2 diabetes, metabolic syndrome, overweight or obesity, as well as those that were healthy. When compared to control diets, including low-fat, Mediterranean, American or Japanese, a diet supplemented with walnuts in amounts varying from 5-24 percent of total calories per day (equivalent to 0.5-3.9 ounces per day) resulted in a significantly greater percent decrease in total cholesterol (3.25%), LDL cholesterol (3.73%), triglycerides (5.52%), and apolipoprotein B (4.19%). In addition, incorporating walnuts into the diet had no adverse effects on body weight or blood pressure, according to the studies included in the meta-analysis.