"A diet that is beneficial for general health is also good for oral health," study co-author Dr. Anwar T. Merchant, of McMaster University in Ontario, Canada, told Reuters Health, adding that "periodontitis may be prevented by diet."
Diabetes and high levels of blood sugar are known to increase a person's risk and severity of periodontitis, while whole grains and fiber have been shown to improve ability to process blood sugar. Yet, whether whole grain consumption is associated with a lower risk of periodontitis had not previously been studied.
To investigate, Merchant and colleagues followed over 34,000 men from the Health Professionals Follow-Up study, gathering information about the men's diet every four years via a food-frequency questionnaire. None of the study participants, who were aged 40-75 years at the start of the study, had a history of periodontitis, heart attack, high cholesterol or diabetes.
Over a 14-year period, 1,897 men were diagnosed with periodontitis, or inflammation of the gums that also involves bone.
Those who reported eating the most brown rice, dark breads, popcorn and other whole grains (about three servings per day) were 23 percent less likely to develop periodontitis than those who reported eating less than one daily serving of whole grains, Merchant and colleagues report in this month's American Journal of Clinical Nutrition.
In other findings, men who reported eating more whole grains were older, more physically active, less likely to smoke, and of lower weight for their height than those who reported the lowest whole grain consumption. They also reported eating more fruits, vegetables and nuts than their counterparts, study findings indicate. After taking all these factors into consideration, however, higher consumption of whole grains was still associated with a lower risk of periodontitis, the report indicates.
According to Merchant, "the likely mechanism is as follows: Whole grain intake improves glucose metabolism, resulting in lower levels of blood glucose. Lower blood glucose levels are reported to reduce the risk of periodontitis in diabetics. Lower blood glucose levels -- resulting from consuming whole grains -- may reduce the risk of periodontitis in non-diabetics as well."
The findings suggest that, without consuming more calories, three or four servings of whole grains -- equal to three or four slices of whole wheat bread, for example -- "may be optimal to reduce periodontitis risk," Merchant told Reuters Health.