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Eating mostly Whole Grains, few Refined
Grains linked to Lower Body Fat
Newswise,
October 2010 — People who consume several
servings of whole grains per day while
limiting daily intake of refined grains
appear to have less of a type of fat tissue
thought to play a key role in triggering
cardiovascular disease and type 2 diabetes,
a new study suggests.
Researchers at the Jean Mayer USDA Human
Nutrition Researcher Center on Aging (USDA
HNRCA) at Tufts University observed lower
volumes of visceral adipose tissue (VAT) in
people who chose to eat mostly whole grains
instead of refined grains.
“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,” says first
author Nicola McKeown, PhD, a scientist with
the Nutritional Epidemiology Program at the
USDA HNRCA.
“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.”
McKeown and colleagues, including senior
author Caroline S. Fox, MD, MPH, medical
officer at The Framingham Heart Study of the
National Heart Lung and Blood Institute (NHLBI),
examined diet questionnaires submitted by
2,834 men and women enrolled in The
Framingham Heart Offspring and Third
Generation study cohorts.
The participants, ages 32 to 83, underwent
multidetector-computed tomography (MDCT)
scans, to determine VAT and subcutaneous
adipose tissue (SAT) volumes.
Visceral fat surrounds the intra-abdominal
organs while subcutaneous fat is found just
beneath the skin. “Prior research suggests
visceral fat is more closely tied to the
development of metabolic syndrome, a cluster
of risk factors including hypertension,
unhealthy cholesterol levels and insulin
resistance that can develop into
cardiovascular disease or type 2 diabetes,”
explains co-author Paul Jacques, DSc,
director of the Nutritional Epidemiology
Program at the USDA HNRCA and a professor at
the Friedman School of Nutrition Science and
Policy at Tufts.
“Not surprisingly, when we compared the
relationship of both visceral fat tissue and
subcutaneous fat tissue to whole and refined
grain intake, we saw a more striking
association with visceral fat. The
association persisted after we accounted for
other lifestyle factors such as smoking,
alcohol intake, fruit and vegetable intake,
percentage of calories from fat and physical
activity.”
Published online September 29 by The
American Journal of Clinical Nutrition, the
present study builds on prior research that
associates greater whole grain intake with
reduced risk of metabolic syndrome and
insulin resistance.
“However, because these studies are
observational, future research that
specifically investigates whole grain intake
and body fat distribution in a larger, more
diverse study population is needed to
identify the mechanism that is driving this
relationship,” Jacques adds.
Additionally, in the present study, the
authors observed that participants who
consumed, on average, three daily servings
of whole grains but continued to eat many
refined grains did not demonstrate lower VAT
volume.
“Whole grain consumption did not appear to
improve VAT volume if refined grain intake
exceeded four or more servings per day,”
says McKeown, who is also an assistant
professor at the Friedman School.
“This result implies that it is important to
make substitutions in the diet, rather than
simply adding whole grain foods. For
example, choosing to cook with brown rice
instead of white or making a sandwich with
whole grain bread instead of white bread.”
This study is funded by the National Heart
Lung and Blood Institute (NHLBI), the USDA,
and a research grant from the General Mills
Bell Institute of Health and Nutrition.
About Tufts University School of Nutrition
The Gerald J. and Dorothy R. Friedman School
of Nutrition Science and Policy at Tufts
University is the only independent school of
nutrition in the United States. The school's
eight degree programs which focus on
questions relating to famine, hunger,
poverty, and communications, are renowned
for the application of scientific research
to national and international policy.
For two decades, the Jean Mayer USDA Human
Nutrition Research Center on Aging at Tufts
University has studied the relationship
between good nutrition and good health in
aging populations. Tufts research scientists
work with federal agencies to establish the
USDA Dietary Guidelines, the Dietary
Reference Intakes, and other significant
public policies.
