ROCHESTER, MINN. -- A recent Mayo Clinic study in the journal Circulation finds that the dietary supplement L-arginine -- touted by the supplement industry as an enhancer for everything from athletic to sexual performance -- improves chest pain symptoms in patients with early heart disease.

"Our study showed that patients who took an L-arginine pill every day for six months had significantly less chest pain and improved coronary blood flow than those who took a placebo," says primary author and Mayo Clinic cardiologist Amir Lerman, M.D. "We propose that there is a role for L-arginine as a therapeutic agent for treating chest pain in some patients with heart disease."

Mayo Clinic investigators studied 26 participants without significant heart disease who were blindly assigned to receive either oral L-arginine or a sugar pill. Researchers assessed the patients? symptoms and their coronary blood flow at the beginning of the study and again after six months of therapy.

"In the patients who received L-arginine, we found marked improvement of symptoms compared with the placebo group," notes Dr. Lerman. "This change began after one week of use and persisted for the six-month study."

Dr. Lerman and colleagues hypothesize that the amino acid L-arginine, through a series of chemical reactions, acts on the lining of blood vessels (endothelium) to relax the vessel wall and may inhibit the build-up of platelets and plaques.

"These findings are exciting," Dr. Lerman says, "but we want to caution patients to discuss the use of L-arginine -- as the use of any supplement -- with their physicians."