For some people, the benefits of eating a healthy diet are hard to
detect on a daily basis. But for otherssuch as those with rheumatoid
arthritisthe effects are often much more palpable.
Rheumatoid arthritis, or RA, is a chronic inflammatory disease with
three diet-associated aspects. One is elevated resting energy expenditure.
Another is elevated whole-body protein catabolisma destructive
form of muscle metabolism that translates to muscle wasting. And yet
another is low body cell mass, which leads to increased fat mass.
Nutritionist Susan B. Roberts, rheumatologist Ronenn Roubenoff, and
colleagues have conducted a study that solves the puzzle as to whether
folks with RA should increase their caloric intake to make up for their
increased resting energy expenditure. Roberts is director of the Energy
Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University in Boston, Massachusetts. Roubenoff
has a visiting appointment with the center.
People with RA tend to be less active than people withoutthe
stiffness and swelling caused by inflammation naturally prompt them
to pursue less physical, more sedentary lifestyles. Such habits lead
in turn to overall gains in fat mass. The combination of high fat mass
and low muscle mass contributes to an increased risk of disability.
Researchers at the center had previously shown that those who develop
RA also develop an increased metabolic rate; they simply burn more calories
while at rest. But they did not know what effect the elevated resting
energy expenditure has on daily total energy expenditure and thus on
dietary energy requirements.
Twenty healthy women and 20 women with RA, all of similar weight and
size, were studied. Their total energy expenditure and their energy
expended during rest and during exercise were measured or estimated.
These three measures make up the major components of the energy balance
The researchers found that in the women with RA, low energy expenditure
from physical activity was directly linked to lower total energy expenditure.
"Even though their basal metabolism is revved up, people with rheumatoid
arthritis tend to be less active than people withoutwhich reduces
their caloric needs," says Roberts. This finding helped solve the
puzzle of whether women with RA need to eat more to make up for the
fact that they burn more calories while at rest. They don't.
The researchers concluded that those with RA should consume nutrient-rich
diets and incorporate physical activity throughout the day to boost
their total energy expenditure. "Such a regimen will help them
improve their physical function and quality of life and maintain a healthy
weight," says Roubenoff.
The study was published in the American Journal of Clinical Nutrition.By
Rosalie Marion Bliss,
Agricultural Research Service Information Staff.
To reach scientists mentioned in this article, contact Rosalie
Bliss, USDA-ARS Information
Staff, 5601 Sunnyside Ave., Beltsville, MD 20705-5129; phone (301)
504-4318, fax (301) 504-1641.
"Nutritional Implications of Rheumatoid Arthritis"
was published in the July
2004 issue of Agricultural Research magazine.