Inside Iowa State: Iowa State University

February 28, 2003

Study rates effectiveness of dietary supplements

by Kevin Brown
A new study by Iowa State researchers has found that two dietary supplements -- creatine and HMB (beta-hydroxy beta-methylbutyrate) -- have a positive effect on lean mass and strength gain in humans when combined with resistance training.

The study by Rick Sharp, professor of health and human performance, and Steve Nissen, professor of animal science, was published in the January 2003 issue of the Journal of Applied Physiology and has been rated as the No. 1 article referenced by online readers.

Sharp and Nissen examined scientific research conducted between 1967 and 2001 on more than 250 dietary supplements. Six of those met their study criteria for review, but only creatine and HMB were shown to significantly affect lean mass or strength gain. The other four supplements studied -- chromium, dehydroepiandrosterone (DHEA), androstenedione and protein (the most widely sold supplement to the public) -- do not significantly affect lean gain or strength.

"There is a disconnect between what the evidence is and what the market is showing us," Sharp said. "The research hasn't borne out any significant benefit of protein-based supplements. The average American already consumes more than enough protein daily to augment lean mass and muscle strength."

However, he added, more studies are being conducted on protein supplements that vary the composition of the protein and timing of its use.

According to the ISU research, creatine and HMB showed significant net gain in lean mass and strength each week. The study also showed a possible additive effect between the two supplements.

"Creatine and HMB both seem to work differently and independently to positively impact lean mass and muscle strength," Sharp said. "That means they could potentially work together for a maximum benefit, which doesn't happen very often."

The safety of creatine and HMB supplements has been addressed in several papers, Sharp said. Creatine shows no adverse health effects. HMB had no major health effects but did result in a net decrease in total cholesterol, LDL cholesterol and systolic blood pressure.

HMB, a natural body-building compound, was discovered through ISU research conducted by Nissen.