Whole grain foods have long been touted for their health benefits. It is claimed that the refinement of grains such as wheat not only destroy some of their nutritional value, but also is connected to an increased incidence of type II diabetes.

Marion Priebe, a nutritionist and epidemiologist at the Center for Medical Biomics, University Medical Center Groningen in the Netherlands, and colleagues reviewed 12 studies that examined relationships between whole grain intake and type 2 diabetes. These studies consisted of a single randomized controlled clinical trial and 11 prospective studies.

Researchers followed groups of people without diabetes over long periods to see whether those who consumed more whole grain foods were less likely to get the disease than other participants were. These studies consistently showed a reduction of risk for the disease in those with a high intake of whole grain foods or cereal fiber.

Priebe said she was surprised that only one randomized trial on this topic exists: “As type 2 diabetes mellitus is reaching epidemic proportions and diet is considered as a modifiable risk factor, it is important to have a sound knowledge of which kinds of food can contribute to the prevention of this disease and to identify gaps in this knowledge.”

Osama Hamdy, M.D., medical director of the Clinical Obesity Program at the Joslin Diabetes Center in Boston, said the kinds of data used within the review are troubling. He said that studies about diabetes prevention should be randomized controlled trials over long durations. Although the concept of a whole–grains-rich diet as a possible diabetes preventative is interesting, he said, none of the review studies would enable any kind of cause-and-effect conclusion.

“This is an additional piece of information that tells us diets rich in whole grains will probably do some good in the prevention of type 2 diabetes,” Hamdy said. “It is not a shortcut to tell you exactly what you need. It is just more support of a concept that has been around for a long time.”

“Whole grain foods are rich in dietary fiber and nutrients and they are recommended to be consumed together with plenty of fruit and vegetables for a healthy diet,” Priebe said. The findings of this review are in line with those recommendations.”