Greater consumption of whole-grain foods correlated with lower total mortality and lower cardiovascular disease mortality, according to a report published online Jan. 5 in JAMA Internal Medicine.
Although the health benefits of eating whole grains are well known, studies that specifically examined the relationship between whole-grain intake and mortality have yielded inconsistent results; several even found an inverse relation between whole-grain consumption and CVD mortality. That may be due, in part, to wide variations among the studies in dietary assessments and failure to properly adjust for participants’ demographic and lifestyle characteristics.
Courtesy of the National Cancer Institute (NCI)
To avoid those pitfalls, researchers examined the relationship using data from two large, prospective cohort studies that meticulously assessed diet every 2 years for an extended period: the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS).
For the analyses, Hongyu Wu, Ph.D., of the department of nutrition at the Harvard School of Public Health, Boston, and her associates assessed data for 74,341 women in the NHS who were followed for 26 years and 43,744 men in the HPFS who were followed for up to 24 years. There were 15,106 deaths among the women and 11,814 among the men.
After the data were adjusted to account for many confounding factors, a greater intake of whole grains was associated with lower total mortality (hazard ratio, 0.91) and lower CVD mortality (HR, 0.85). Every additional daily serving of whole grains was associated with a 5% decrease in total mortality and a 9% decrease in CVD mortality.
In a food-substitution analysis, replacing one serving of refined grains with one serving of whole grains every day was associated with a 4% decrease in total mortality and an 8% decrease in CVD mortality. Replacing one serving of red meat with one serving of whole grains was associated with a 10% decrease in total mortality and a 20% decrease in CVD mortality, the investigators said (JAMA Intern. Med. 2014 Jan. 5 [doi:10.1001/jamainternmed.2014.6283]).
Those associations were independent of numerous demographic and lifestyle predictors of mortality, and they persisted across subgroups of participants who had varying risk profiles.
The findings support current dietary guidelines and suggest that a diet enriched with whole grains may confer benefits that extend life expectancy, Dr. Wu and her associates said.
Most of the participants in the NHS and the HPFS were well-educated professionals of European ancestry, however, so these findings may not be generalizable to other demographic or ethnic groups, the authors cautioned.
The study was supported by research grants from the National Institutes of Health and the National Heart, Lung, and Blood Institute. Dr. Wu and her associates reported having no financial disclosures.