Visceral adipose tissue (VAT) – or fat around the abdominal organs – has been associated with higher risk of metabolic syndrome, a condition characterized by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type-2 diabetes and cardiovascular disease.
This latest study, published in the American Journal of Clinical Nutrition, examined nutrition survey data and body fat scans of 2834 individuals aged 32 to 83, and adjusted results to take account of other lifestyle factors, such as smoking, alcohol intake, and fruit and vegetable consumption.
"VAT volume was approximately ten percent 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 of Tuft’s University.
In addition, those study participants who consumed four or more portions of refined grain per day had a diminished association between whole grain consumption and VAT, suggesting that high intake of refined grains can cancel out the effect of whole grains on fat distribution.
“This result implies that it is important to make substitutions in the diet, rather than simply adding whole grain foods,” McKeown said.
The current 2005 Dietary Guidelines for Americans recommend consumption of at least three portions of whole grain foods per day, but the study’s authors said that more education is needed to help the public understand what is meant by the term ‘whole grain’, how much constitutes a portion, and the health benefits of substituting refined grain foods for whole grain ones.
The researchers counted one serving of whole grains as a cup of cold breakfast cereal; half a cup of cooked oatmeal, brown rice, or other grains; one slice of dark bread; three cups of popcorn; or two tablespoons of added bran or added germ.
Refined grains were counted as refined-grain breakfast cereals, white bread, English muffins, bagels, muffins, biscuits, white rice, pasta, pancakes, waffles, crackers, and pizza.
Source: American Journal of Clinical Nutrition
"Whole- and refined-grain intakes are differentially associated with abdominal visceral and subcutaneous adiposity in healthy adults: the Framingham Heart Study"
Authors: Nicola M McKeown, Lisa M Troy, Paul F Jacques, Udo Hoffmann, Christopher J O’Donnell, and Caroline S Fox