Whole grains linked to lower prediabetes risk

Eating whole grains is associated with a decreased risk of prediabetes, a blood sugar elevation that can precede diabetes in adults, according to new research.

Swedish residents who ate food containing more than 59 grams - roughly two ounces - of whole grains per day were 27 percent less likely to become prediabetic compared with residents who ate 30 grams or less, according to the research.

"This is of great importance because prediabetes is increasing," lead author Tina Wirström, a postdoctoral fellow at the Karolinska University Hospital in Sweden, told Reuters Health.

The American Diabetes Association estimates that one in four Americans older than 20 have prediabetes. Nearly a quarter of people with prediabetes eventually develop full-blown diabetes.

Previous research has linked whole grain rich diets with a decreased risk of diabetes, but the new study in the American Journal of Clinical Nutrition makes the connection to the disease precursor. Whole grains range from oatmeal to popcorn, from brown rice to whole wheat - as long as the entire kernel is consumed.

The study included 5,477 Stockholm residents from 35 to 56 years old without diabetes who kept food diaries of how much whole and refined grains they ate. Researchers measured blood glucose in study participants and followed up 10 years later.

Overall, one in 13 participants became prediabetic, while one in 33 became diabetic, the study found. When researchers took into account the daily amount of whole grains eaten, they found that eating more than 59 grams versus 30 grams of whole grain was associated with a 27 percent decreased risk of becoming prediabetic.

The association was stronger for men, and those with an increased genetic risk for developing diabetes did not see a difference, researchers found.

RELEVANT TO U.S.?

Nutrition experts noted that the study had little relevance to the U.S. since most Swedes get their grains from whole grain sources such as rye crisps. In contrast, Americans get most grains from refined wheat such as flour that contains fewer nutrients and fiber compared to rye.

"To say it has any relevance to the U.S. is really a stretch," said Joanne Slavin, nutrition professor at the University of Minnesota, who was not involved in the current study.

U.S. food manufacturers can label food that contains eight grams per serving as whole grain, whereas Sweden requires that a food product contain at least half whole grains to receive the label.

Many foods with claims of whole grain goodness have extra calories, fats and carbohydrates in addition to the grains, which can be risk factors for diabetes, Slavin said.

Further, fewer than three percent of Americans get the recommended 48 grams per day of whole grains. The average American eats 15 grams of whole grain daily.