Decades-long cohort study links nut consumption with lower mortality rates

(http://www.nejm.org/doi/full/10.1056/NEJMoa1307352#t=articleResults) Nuts are already known to be a healthy, nutrient-dense food, and even the Food and Drug Administration suggests that daily nut consumption as part of a low-fat diet "may reduce the risk of heart disease." However, few studies have investigated nut consumption in relation to total mortality, and many that have are quite limited. That is why researchers from Boston and Indianapolis teamed up to evaluate the health benefits of eating nuts.

The researchers followed 76,464 women and 42,498 men who were respectively in the Nurses' Health Study and the Health Professionals Follow-up Study. Throughout the study and follow-up, researchers evaluated the individuals' nut consumption through 2-year interval surveys and kept track of participant mortality and causes of death.

At the end of the study, the researchers found that "those who consumed nuts more frequently were leaner, less likely to smoke, more likely to exercise, and more likely to use multivitamin supplements; they also consumed more fruits and vegetables and drank more alcohol." They also discovered that nut consumption was inversely associated with deaths due to cancer, heart disease and respiratory disease, in addition to being associated with reduced weight gain.

Based on a serving size of 28 g, or 1 oz, the researchers found relationships between nut consumption and mortality as follows:

Seven servings or more per week: 20% lower death rate.

Five or six per week: 15% lower death rate.

Two to four per week: 13% lower death rate.

One per week: 11% lower death rate.

Less than one per week: 7% lower death rate.

The mortality rates are based off of hazard ratios for death which all had a 95% confidence interval and are in comparison to those who reported eating no nuts.

The researchers wrote in their study, "In conclusion, our analysis of samples from these two prospective cohort studies showed significant inverse associations of nut consumption with total and cause-specific mortality." However, they warn that cause and effect relationships cannot yet be established and call for controlled, randomized clinical trials for further investigation.