Nutritional Supplements May Combat Muscle Loss

Nutritional supplements may lessen muscle atrophy, show early findings from a study conducted by scientists associated with the National Space Biomedical Research Institute, a consortium of 12 medical institutions including several Texas Medical Center institutions. The institute is charged with studying the health risks related to long-duration space flight, with the ultimate goal of benefiting patients on Earth, since many health conditions related to space flight also affect non-astronaut patients.

To study space travel’s effect on muscles, Robert Wolfe, M.D. with The University of Texas Medical Branch at Galveston, enlisted healthy subjects to stay in bed 28 days.

“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 Arny Ferrando, M.D., professor of surgery at UTMB and Shriners Hospital for Children in Galveston.

When muscles are inactive, they don’t synthesize, or make, new proteins. In the study, researchers attempted to increase protein production by giving participants amino acids – the raw materials from which proteins are made. Participants received the supplements in a drink three times a day, and researchers compared participants’ protein synthesis/breakdown rates and muscle mass before and after their 28 days in bed. 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 remained in bed and got up only briefly to use a bedside commode. They ate and bathed from their beds, and daily activities were limited to watching television, reading books and using a bedside computer.

Midway through the study, researchers determined muscle mass and function by testing the subjects’ strength and body composition. They gathered the protein synthesis and breakdown rates by using stable isotope analysis. With the stable isotope technique, researchers attached a harmless tracer to specific amino acids that traveled through the bloodstream. Then, they took blood samples to determine the amount of amino acids that entered and exited 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 Douglas Paddon-Jones, M.D., also of UTMB and a co-investigator performing these studies. “We completed 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 the institute’s nutrition and fitness research team. “This 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. Researchers duplicated the cortisol concentrations found during space flight, then determined protein synthesis and breakdown rates of the subjects taking the supplement and compared this to the rates of the control group.

Findings from this research on nutritional supplements could potentially 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.

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