"The take home message is that higher consumption of whole grain should be promoted based on research on whole grain and lower risk of type 2 diabetes as well as other chronic diseases," said lead researcher Dr. Rob van Dam.
The Black Women's Health Study -- published in the October issue of Diabetes Care -- observed over 41,000 black women with an average age of 39, for eight years. The diet of the participants was assessed using a 68-item food frequency questionnaire, and diabetes incidence was evaluated through a different questionnaire every two years.
By the end of the study, nearly 2,000 cases of type 2 diabetes were diagnosed, and van Dam and colleagues noted that the women with the highest magnesium intake (about 244 milligrams a day, average) had a 35 percent lower risk for the disease than those with the lowest intake (an average of about 115 milligrams a day). Women who consumed the most whole grains (one or more servings a day) had a 31 percent lower risk for diabetes than women who consumed less than one serving a week.
These results were found after taking into consideration factors such as alcohol and tobacco use, body mass index, age, family history of diabetes, soft drink consumption and calcium intake, along with several others.
"These findings indicate that higher consumption of magnesium-rich foods, particularly wholegrain products, is associated with a lower risk of type-2 diabetes in African-American women," wrote the researchers.
The researchers said that it was unclear whether the results similar to those obtained in the study would also be observed using magnesium supplements. Van Dam said that further studies were needed to evaluate whether magnesium can improve glucose homeostasis.
"These are encouraging findings, and if whole grains can create this kind of positive impact, imagine what daily nutritional supplementation might accomplish in these women," said Mike Adams, author of the "Seven Laws of Nutrition." "Good nutrition is the number one strategy for preventing diseases like diabetes, cancer, heart disease and depression, and the more people who switch from white flour to whole grain flour, the healthier our nation will be."
Whole grains have recently increased in popularity among consumers for their health benefits, and subsequently among food producers. The FDA allows companies to claim a link between foods and a reduced risk of heart disease and some cancers on the labels, as long as they are low in total fat and contain at least 51 percent whole grains by weight.
According to the American Diabetes Association, more than 20 million people in the United States suffer from diabetes; roughly 7 percent of the population. The treatment costs of the disease are as much as $132 billion, $92 billion of which goes to medication.