Nutritional Supplements May Combat Muscle Loss

[Guest guest]

Source:   National Space Biomedical Research Institute

(http://www.nsbri.org/)

Date:   Posted 8/28/2002

Nutritional Supplements May Combat Muscle Loss

HOUSTON - (Aug. 27, 2002) - Early indications show that nutritional

supplements may lessen muscle atrophy brought on by space travel, prolonged

bed confinement or immobility.

To study space travel's effect on muscles, Dr. Wolfe of the

University of Texas Medical Branch at Galveston enlisted healthy subjects to

stay in bed 28 days during a National Space Biomedical Research Institute

study.

" One cause of muscle atrophy in space is lack of muscular activity. That's

why bed rest is a good model because it minimizes activity, and like

astronauts, you lose muscle mass primarily in the legs, " said

co-investigator Dr. Arny Ferrando, a professor of surgery at UTMB and

Shriners Hospital for Children in Galveston. " When muscles are inactive, as

they are in space, they don't make new proteins. If muscle breakdown rates

are the same, that means you lose muscle. "

Researchers are attempting to increase protein synthesis rates with

supplements of amino acids, which are the raw materials of protein.

Participants received the supplements three times a day, and researchers

compared the protein synthesis/breakdown rates and muscle mass before and

after the bed-rest study. This data was compared to results from a control

group that received a placebo drink instead of the supplements.

" Early results suggest that the amino acid supplement is able to maintain

synthesis rates and body mass, " Ferrando said.

During the study, subjects must remain in bed and can get up only briefly to

use a bedside commode. They eat and bathe from their beds, and daily

activities encompass watching television, reading books and using a bedside

computer.

Midway through the study, researchers determine muscle mass and function by

testing the subjects' strength and body composition.

They gather the most vital data, the protein synthesis and breakdown rates,

by using stable isotope analysis. With the stable isotope technique,

researchers attach a harmless tracer to specific amino acids that travel

through the bloodstream. Then, they take blood samples to determine the

amount of amino acids that enter and exit the leg.

" If 80 amino acids are coming into the artery and 60 are going out of the

vein, we know that 20 were probably made into proteins in the muscle, " said

Dr. Paddon-, also of UTMB and a co-investigator performing

these studies. " We complete the muscle analysis by removing a small piece of

muscle and determining how many amino acids have been incorporated into

proteins. Over time, we can calculate the rate at which the synthesis and

breakdown occurs. "

Space conditions also elevate the body's level of the stress hormone

cortisol, which increases the breakdown rate of proteins. " Under stress, the

body breaks down proteins to make energy for survival, " said Ferrando, a

member of NSBRI's nutrition and fitness research team. " However, this

process also causes muscle atrophy. "

To study the supplement's effects on muscle loss due to elevated levels of

cortisol, researchers infused the stress hormone into the participants'

blood during the stable isotope tests. The researchers mimic the cortisol

concentrations found during space flight, then determine protein synthesis

and breakdown rates of the subjects taking the supplement and compare this

to the rates of the control group.

Ferrando and Wolfe are also collaborating with other NSBRI researchers who

use the subjects' body fluids to study changes in bone, immune function and

cell damage induced by bed rest.

Findings from this research on nutritional supplements could benefit

patients on Earth.

" Muscle atrophy is common in many populations: the elderly, kids with burns,

patients in intensive care or people who have had major operations. We're

looking at this phenomenon in terms of space flight, but the study has many

other implications, " Ferrando said.

The NSBRI's consortium members include Baylor College of Medicine,

Brookhaven National Laboratory, Harvard Medical School, The s Hopkins

University, Massachusetts Institute of Technology, Morehouse School of

Medicine, Mount Sinai School of Medicine, Rice University, Texas A & M

University, University of Arkansas for Medical Sciences, University of

Pennsylvania Health System and University of Washington.