July 25, 2006

Amino Acid Supplement Has Benefits in Heart Failure

NEW YORK (Reuters Health) - Dietary supplementation with the amino acid L-arginine may improve the physical fitness of heart failure patients by enhancing their endurance to exercise, according to a study.

Heart failure is a condition characterized by an enlarged heart that pumps blood inefficiently, resulting in breathlessness and fluid accumulation in the limbs and lungs.

L-arginine is a precursor of nitric oxide, a compound that plays a key role in the heart and circulatory system, both at rest and during exercise. Nitric oxide helps the inner lining of blood vessels to dilate.

Dysfunction of the "L-arginine-nitric oxide" pathway in heart failure leads to reduced blood flow at rest and during exercise, partly explaining the exercise capacity limitations of chronic heart failure patients.

Dr. Stephane Doutreleau and colleagues from Institut de Physiologie, Strasbourg, France, examined the potential benefits of 6 weeks of L-arginine supplementation on endurance exercise in 10 patients with chronic stable heart failure.

The patients performed an identical endurance exercise test before and after 6 weeks of L-arginine supplementation (n = 6) or no supplementation (control group; n = 4).

Patients who took L-arginine experienced a significant decrease in their average heart rate throughout exercise and the recovery period, the team reports in the International Journal of Sports Medicine. There were no significant changes in blood pressure and respiratory parameters.

These findings indicate that chronic L-arginine supplementation might be useful as add-on therapy to improve patients' physical fitness, the team concludes.

The current study supports a prior study in which a group of heart failure patients were shown to benefit from a combination of exercise and L-arginine supplements. In that study, the combination appeared to help correct the abnormal functioning of blood vessels seen in chronic heart failure.

SOURCE: International Journal of Sports Medicine July 2006.