Whole grains may reduce risk of type 2 diabetes

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Whole grains may reduce risk of type 2 diabetes

Last Updated: 2002-05-07 14:39:13 -0400 (Reuters Health)

Suzanne Rostler

NEW YORK (Reuters Health) - Consuming a diet rich in whole grains may

help overweight adults to reduce their risk of type 2 diabetes,

according to a recent report.

The study found that insulin sensitivity improved in a group of

overweight and obese adults when they consumed a diet rich in

whole-grain foods such as brown rice, oats, corn and barley. Insulin

sensitivity is a measure of how efficiently the body responds to

insulin, the hormone responsible for depositing glucose (sugar) from the

blood following a meal or snack, into cells throughout the body to use

as energy.

Patients with type 2 diabetes become desensitized to insulin and as a

result, their blood glucose can remain elevated. If not controlled

through diet or medication, elevated blood sugar eventually raises the

risk of heart disease, kidney damage and other problems.

" Insulin sensitivity may be an important mechanism whereby whole-grain

foods reduce the risk of type 2 diabetes and heart disease, " Dr. Mark A.

Pereira from Harvard University in Boston, Massachusetts, and colleagues

conclude.

The findings support the US Department of Agriculture's (USDA)

recommendation to consume six to 11 servings of carbohydrates daily,

including servings from whole grain sources. In the US, the majority of

grains are refined, meaning they have been stripped of their bran and

depleted of fiber, minerals and other healthy compounds.

But studies have shown that fiber may slow the release of glucose into

the blood, and lower concentrations of blood sugar require less insulin

to be released into the blood. Over time, lower insulin levels may help

the cells to remain sensitive to the hormone whereas excess insulin may

desensitize the cells.

" People should be encouraged to replace the refined-grain foods in their

diet, such as white bread and bagels, refined-grain breakfast cereals,

and white rice with whole grain choices, " Pereira said.

He warned consumers to steer clear of products that do not list " whole

grain " as the first ingredient.

" Often, breads will mention 'wheat flour' on the label but this does not

mean that the product is made with the whole grain, including the bran

and germ. Often, wheat flour is refined wheat in the form of the common

white flour, " Pereira said.

In the study, 11 sedentary adults with a body mass index (BMI) of at

least 27 consumed a diet in which 55% of total calories came from either

whole-grain carbohydrates or processed carbohydrates, for 6 weeks. A

BMI--a measure of weight in relation to height--of at least 25 is

considered overweight, while 30 and above is considered obese.

Following the initial 6-week period study volunteers ate their usual

diet for 6 to 9 weeks and then switched to the alternate diet for the

following 6 weeks.

Insulin levels were 10% lower and blood glucose levels were slightly

reduced when study volunteers ate a whole grain-rich diet, regardless of

body weight, according to the results in the April issue of the American

Journal of Clinical Nutrition. Excess weight is a risk factor for

insulin resistance, they note.

" Whole-grain foods may have favorable effects on insulin sensitivity, "

Pereira and colleagues conclude. " These effects may reduce the risk of

type 2 diabetes and heart disease. "

SOURCE: American Journal of Clinical Nutrition 2002;75:848-855.