An updated systematic review of 25 years of research on the effect of walnut consumption on cardiovascular risk factors suggest that walnut-enriched diets may lead to significantly greater reductions in total cholesterol, LDL cholesterol, triglycerides, and apolipoprotein B, compared to control diets.
Walnut consumption had no adverse effects on body weight or blood pressure.
Most of the trials in this review had relatively small sample sizes, which could limit the ability to determine significant effects, and in some cases, the amount of walnuts consumed was relatively large and might be difficult to maintain in a real-world setting. However, researchers still saw significant benefits when lower amounts of walnuts were consumed (less than 28 grams per day), particularly with total and LDL cholesterol.
Guasch-Ferré M, Li J, Hu FB, et al. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials [published online ahead of print June 21, 2018]. Am J Clin Nutr. doi: 10.1093/ajcn/nqy091
Banel HK, Hu FB. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review. Am J Clin Nutr. 2009;90(1):56-63.