Despite the popularity of such grain-eschewing diets as the Paleo and the gluten-free craze, a new study has found that people who eat a whole grain-rich diet live longer.
In fact, eating more whole grains may decrease people's risk of death by up to 15%, particularly from heart disease, according to a large new long-term study from the Harvard School of Public Health (HSPH).
Much of that benefit probably comes from the bran, the fibrous coating that processing removes from whole wheat and brown rice. Bran intake alone was linked with up to 6% lower overall death risk and up to 20% lower cardiovascular disease-related risk.
The study appears online in JAMA Internal Medicine.
"This study further endorses the current dietary guidelines that promote whole grains as one of the major healthful foods for prevention of major chronic diseases," said Qi Sun, assistant professor in the Department of Nutrition at HSPH and senior author of the study.
The findings "also provide promising evidence that suggests a diet enriched with whole grains may confer benefits toward extended life expectancy," the researchers write in their report. (The Harvard School of Public Health recommends that people get one-quarter of their daily calories from whole grains; the federal government's most recent Dietary Guidelines recommend consuming at least half of all grains as whole grains.)
Whole grains contain a range of beneficial nutrients, from fiber to magnesium, vitamin E and plant-based compounds called phytochemicals, that are stripped from refined white flour and white rice. These grains, such as whole wheat, brown rice, whole oats, barley, farro and others found in those mysterious
Although eating more whole grains has been previously linked with a lower risk of major chronic diseases, such as type 2 diabetes and cardiovascular disease, until now there had been limited evidence regarding whole grains' association with mortality.
Harvard researchers and colleagues 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 cardiovascular disease-related mortality. For each serving of whole grains (measured as 28 grams per day), the overall death risk dropped by 5%, and by 9% for cardiovascular disease-related death.
However, eating whole grains doesn't appear to affect the risk of dying from cancer. The researchers also didn't find any decreased overall mortality risk from eating germ, another component of whole grains.
Replacing refined grains and red meats with whole grains is also likely to lower mortality risk, according to the study. Swapping just one serving of refined grains for whole grains reduced cardiovascular disease-related deaths by 8%; swapping out one serving of red meat for whole grains lowered that risk by a whopping 20%.