Nut consumption has previously been associated with a reduced risk of a number of major chronic diseases such as cardiovascular disease and type 2 diabetes, but until recently the association of nut consumption and mortality has been unclear. Looking at mortality overall as opposed to just specific diseases may give some indications that there are benefits to eating nuts that have yet to be clearly identified.
To address the impact of nut consumption on mortality, a team of researchers looked at two large studies that tracked participants’ nut consumption. One was the Nurses’ Health Study of 76,464 women and the other was the Health Professionals Follow-up Study of 42,498 men. The period studied in both studies was 1986 to 2010, and each study measured nut consumption at the start of the study and at two- to four-year intervals.
Over the course of these studies, 16,200 women and 11,229 men passed away. In both studies nut consumption was associated with a lower likelihood of mortality, even after other risk factors and demographics were adjusted for. In particular, those individuals who ate a serving of nuts at least seven times a week had the greatest reduction in mortality risk. Those who consumed an average of one serving of nuts daily or more had a 20 percent lower risk of mortality. Those who ate nuts five to six times a week had a 15 percent reduced risk; those who ate them two to four times a week had a 13 percent lower risk; once or twice a week had an 11 percent reduced risk; and even those who ate nuts less than once a week on average had a seven percent reduced risk compared to individuals who did not consume nuts at all.
This relationship between nuts and mortality remained significant even when smokers, individuals with very high or low body mass, and diabetics were excluded from the analysis. The relationship also remained when sodium intake, consumption of olive oil, and scores on a Mediterranean-diet scale were adjusted for.
The researchers also looked at peanut and tree nut consumption separately, since these two groups differ in their composition and nutritional content. Interestingly, the association of both of these with both overall mortality and specific causes of mortality were quite similar. For all individuals who consumed nuts two or more times a week, peanuts reduced the overall risk by 12 percent, compared to 15 percent for tree nuts.
In looking at other differences in these participants, the researchers also noted that the association of nut consumption with decreased mortality risk was stronger among overweight or obese individuals than for individuals of normal weight. Additionally, despite their high calorie content, in both groups studied here nut consumption was associated with less weight gain.
When the researchers looked at the impact of nut consumption on specific causes of death, they found a significant decrease in the risk of death due to cancer, heart disease, and respiratory disease.
Much of the health benefits observed may be due to nuts being a nutrient-dense food. Nuts are rich in unsaturated fatty acids, fiber, vitamins, minerals, and antioxidants. Studies have also suggested that nuts may have a beneficial impact on a number of contributors to chronic diseases, such as inflammation, hyperglycemia, insulin resistance, and abdominal fat. However additional research is still required to fully explain the health benefits suggested by this data.