Higher dietary intake of fiber from grains and cereals and of magnesium may each be associated with a lower risk of type 2 diabetes, according to a report and meta-analysis in the May 14 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Projections indicate that the number of people diagnosed with diabetes worldwide may increase from 171 million in 2000 to 370 million by 2030, according to background information in the article. The associated illness, death and health care costs emphasize the need for effective prevention, the authors write. Fiber may help reduce the risk of diabetes by increasing the amount of nutrients absorbed by the body and reducing blood sugar spikes after eating, among other mechanisms. Current American Diabetes Association guidelines include goals for total fiber intake, but research suggests that some types of fiber may be more beneficial than others. Findings regarding magnesium and diabetes risk remain unclear.
Matthias B. Schulze, Dr.P.H., and colleagues at the German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, conducted a study of 9,702 men and 15,365 women age 35 to 65 years. Participants completed a food questionnaire when they enrolled in the study between 1994 and 1998, then were followed up through 2005—an average of seven years—to see if they developed diabetes. In addition, the researchers performed a meta-analysis of previously published work related to intake of fiber or magnesium and risk of diabetes.
During the follow-up period, 844 individuals in the study developed type 2 diabetes. Those who consumed more fiber through cereal, bread and other grain products (cereal fiber) were less likely to develop diabetes than those who ate less fiber. When the participants were split into five groups based on cereal fiber intake, those who ate the most (an average of 17 grams per day) had a 27 percent lower risk of developing diabetes than those in the group that ate the least (an average of 7 grams per day). Eating more fiber overall or from fruits and vegetables was not associated with diabetes risk, nor was magnesium intake.
In the meta-analysis, the researchers identified nine studies of fiber and eight studies of magnesium intake. Based on the results of all the studies, in which participants were classified into either four or five groups according to their intake of fiber or magnesium, those who consumed the most cereal fiber had a 33 percent lower risk of developing diabetes than those who took in the least, while those who consumed the most magnesium had a 23 percent lower risk than those who consumed the least. There was no association between fruit or vegetable fiber and diabetes risk.
"In conclusion, the evidence from our study and previous studies, summarized by means of meta-analysis, strongly supports that higher cereal fiber and magnesium intake may decrease diabetes risk," the authors conclude. "Whole-grain foods are therefore important in diabetes prevention."
(Arch Intern Med. 2007;167:956-965. Available pre-embargo to the media at www.jamamedia.org.)
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