Although eating more whole grains has been previously associated with a lower risk of major chronic diseases, such as type 2 diabetes and cardiovascular disease (CVD), until now there had been limited evidence regarding whole grains' link with mortality. The researchers looked at data from more than 74,000 women from the Nurses' Health Study and more than 43,000 men from the Health Professionals Follow-Up Study who filled out questionnaires about their diet every two or four years from the mid-1980s to 2010. Adjusting for a variety of factors, such as age, smoking, body mass index, physical activity, and overall diet excluding whole grains, the researchers compared the participants' whole grain intake with mortality data over an approximately 25-year period.
They found that whole grain intake was associated with up to 9% decreased risk of overall mortality and up to 15% decreased risk of CVD-related mortality. For each serving of whole grains (28 g/day), the overall death risk dropped by 5%, and by 9% for CVD-related death. They also found that bran, a component of whole grain foods, was associated with similar beneficial effects. Bran intake was linked with up to 6% lower overall death risk and up to 20% lower CVD-related risk.
In contrast, the researchers found no association between eating whole grains and lowered cancer-related mortality risk. They also didn't find any decreased risk from eating germ, another essential component of whole grains.