In July 2018 researchers from the USA and Spain published their review of the medical scientific literature to assess the effects of walnut consumption on blood lipids and other cardiovascular risk factors. A total of 26 studies involving 1,059 individuals were included in the review. Results showed that walnut-enriched diets produced greater reductions in total cholesterol, LDL(bad)-cholesterol and triglyceride levels than control diets. Walnut-enriched diets also produced more pronounced reductions in blood lipids when compared to both American and Western diets. However, a comparison between control diets and walnut-enriched diets did not show significant differences in weight change or blood pressure levels.
Guasch-Ferré M et al. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials. Am J Clin Nutr. 2018 Jul 1;108(1):174-187