New England Journal of Medicine, 2013 · Prospective cohort
In two large US cohorts of nurses and other health professionals, followed for up to 30 years, people who ate nuts seven or more times a week had a 20% lower death rate than those who ate none, after adjusting for other risk factors. This is an association, not proof of cause, and the study was part-funded by the International Tree Nut Council.
Always read the original paper for context — effect sizes, study populations and funding sources matter.
