The study's findings are consistent with previous research, is the largest of its kind to date, and appears in the November 21 issue of New England Journal of Medicine. The results are based on about three decades of follow-up among 76,464 women in the Nurses' Health Study (1980-2010) and 42,498 men in the Health Professionals Follow-up Study (1986-2010), including examination of food questionnaire data.
Compared to people who did not eat nuts, people who ate nuts saw benefits that increased along with the number of servings of nuts they ate. That is, people who ate nuts once a week saw a smaller, but still significant benefit, while those who ate nuts seven or more times per week had a nearly doubled benefit.
The benefits were seen in both men and women, independent of other predictors for mortality. The study authors conclude that "the findings from our study and others suggest a potential benefit of nut consumption for promoting health and longevity."
These new findings build on existing knowledge about the role of nuts in heart health. Even a decade ago in 2003, there was enough science for the U.S. Food and Drug Administration to approve a qualified health claim related to nuts that states "Scientific evidence suggests but does not prove that eating 1.5oz. per day of most nuts, such as pistachios, as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease [See nutrition information for fat content]."
This observational study is an important addition to the body of research on nuts and heart health; however, given its observational nature, it's not possible to conclude cause and effect between nut consumption and mortality.