A meta-analysis of 61 controlled trials has concluded that consuming tree nuts, such as walnuts, lowers total cholesterol, triglycerides, LDL cholesterol, and ApoB, the primary protein found in LDL cholesterol. Walnuts were investigated in 21 of the 61 trials, more than any other nut reviewed.
Consuming at least two servings (two ounces) per day of tree nuts had stronger effects on total cholesterol and LDL. The evidence also suggests that tree nut consumption may be particularly important for lowering the risk of heart disease in individuals with type 2 diabetes.
Walnuts have also been shown to reduce inflammation, and improve arterial function.
Del Gobbo, L., Falk, M.C., Feldman, R., Lewis, K., Mozaffarian, D. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis and dose-response of 61 controlled intervention trials. Am J Clin Nutr.2015; doi: 10.3945/ajcn.115.110965.
Kris-Etherton P. Walnuts decrease risk of cardiovascular disease: a summary of efficacy and biologic mechanisms. J Nutr. 2014; 10.39:2S-8S.
Zhao G, Etherton TD, Martin KR, et al. Dietary alpha-linolenic acid reduces inflammatory and lipid cardiovascular risk factors in hypercholesterolemic men and women. J Nutr 2004; 134: 2991-2997.