Boston, MA - Eating more whole grains may reduce the risk of premature death, according to a new meta-analysis by researchers from Harvard T.H. Chan School of Public Health. The study found that people who ate the most whole grains (70 grams/day, about 4 servings), compared with those who ate little or no whole grains, had a lower risk of dying during the study period.
"These findings further support current dietary guidelines that recommend at least 3 daily servings (or 48 grams) of whole grains to improve long-term health and prevent premature death," said Qi Sun, assistant professor in the Department of Nutrition and senior author of the study.
The study will appear online June 13, 2016 in Circulation.
Previous studies have found that whole grains may reduce risk of cardiovascular disease (CVD), diabetes, and poor gut health, among other conditions.
The meta-analysis combined results from 12 published studies, in addition to unpublished results from the National Health and Nutrition Examination Survey (NHANES) III and NHANES 1999-2004. The studies were conducted in the United States, the United Kingdom, or in Scandinavian countries between 1970 and 2010. Health information from 786,076 participants was included in the analysis.
The results showed that people who ate 70 grams/day of whole grains, compared with those who ate little or no whole grains, had a 22% lower risk of total mortality, a 23% lower risk of CVD mortality, and a 20% lower risk of cancer mortality.
Mortality rate is a measure of the number of deaths in a particular population for a specific period of time.
The researchers note that multiple bioactive compounds in whole grains could contribute to their health benefits, and that high fiber content may lower cholesterol production and glucose response and increase satiety.
The researchers recommend that people choose foods that are high in whole grain ingredients--such as bran, oatmeal, and quinoa--that have at least 16 grams per serving, while reducing consumption of unhealthy refined carbohydrates.
One limitation of the meta-analysis was that some of the studies used were carried out before a more consistent definition of whole grains became available; therefore, lists of whole grain foods varied substantially among individual studies. In addition, as most of the studies were from the U.S. and Scandinavian countries, it is not known whether these findings can be generalized to other populations.
Other Harvard Chan authors included lead author Geng Zong, Alisa Gao, and Frank Hu.
Funding for the study came from by NIH grants ES022981 and ES021372. Qi Sun was supported by a career development award, R00-HL098459, from the National Heart, Lung, and Blood Institute.
"Whole Grain Intake and Mortality from All Causes, Cardiovascular Disease, and Cancer: A Meta-analysis of Prospective Cohort Studies," Geng Zong, Alisa Gao, Frank B. Hu, and Qi Sun, Circulation, online June 13, 2016, doi: 10.1371/journal.pmed.1002039
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Harvard T.H. Chan School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory to people's lives--not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at Harvard Chan School teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as America's oldest professional training program in public health.