People who regularly eat whole grains rather than refined grains pack on less of the type of fat linked to a higher risk for heart disease and type 2 diabetes, new research suggests.
In high amounts, visceral adipose tissue (VAT) - the fat that surrounds the intra-abdominal organs - is associated with the onset of high blood pressure, high cholesterol and insulin resistance, health risk factors collectively known as the "metabolic syndrome".
"VAT volume was approximately 10% lower in adults who reported eating three or more daily servings of whole grains and who limited their intake of refined grains to less than one serving per day," said study co-author Nicola McKeown, a scientist with Tufts University's nutritional epidemiology programme at the Jean Mayer USDA Human Nutrition Research Center on Aging.
"For example, a slice of 100% whole-wheat bread or a half-cup of oatmeal constituted one serving of whole grains and a slice of white bread or a half-cup of white rice represented a serving of refined grains," she said.
The findings, published online in the American Journal of Clinical Nutrition, stem from an analysis of dietary surveys and body-fat scans conducted among more than 2,800 men and women between the ages of 32 and 83.
Even after accounting for additional lifestyle factors including smoking history, alcohol consumption, fruit and vegetable intake, percentage of calories comprised of fat, and physical activity routines, the authors found that consuming several servings a day of whole grains is associated with lower amounts of VAT.
However, those who consumed three servings a day of whole grains and several daily servings of refined grains did not appear to benefit from the whole grain-lower VAT connection.
"Whole grain consumption did not appear to improve VAT volume if refined grain intake exceeded four or more servings per day," noted McKeown.
"This result implies that it is important to make substitutions in the diet, rather than simply adding whole grain foods," she advised. "For example, choosing to cook with brown rice instead of white, or making a sandwich with whole-grain bread instead of white bread."