NEW YORK (Reuters Health) – Angina patients given a medical food bar enriched with L-arginine, as an adjunct to traditional treatment, have improved vascular function, exercise capacity, and quality of life, researchers report in the January 2nd issue of the Journal of the American College of Cardiology.
In addition to L-arginine, the bar contains folate, vitamins C, E, B6 and B12, niacin, and soy isoflavones. Cooke Pharma, Silver Springs, Maryland, produces the medical food bar, called the HeartBar.
Dr. Andrew J. Maxwell, with Cooke Pharma's R & D division in Newark, California, and colleagues tested the ability of the food bar to enhance endothelium-derived nitric oxide. The researchers selected 36 patients with stable angina to participate in a randomized crossover trial of two 2-week treatment periods. During each phase subjects ate two L-arginine-enriched bars per day or placebo bars. Subjects were instructed to continue with their current medications, lifestyle, and diet.
When patients received the medical bar, flow-mediated percent increase in brachial artery diameter improved from a mean of 5.5 to 8.0 (p = 0.004), while there was no change during the placebo period.
Exercise time also improved by an average of 16% compared with placebo (p = 0.05). "While there was no evidence of improvement in ECG manifestations of ischemia or angina onset time, there was also no worsening of these parameters or increase in measures of cardiac work despite the observed improvement in exercise capacity," the investigators note.
Also, quality of life scores, measured by the SF36, increased during treatment with the medical bar from 64 to 68 (p = 0.04), Dr. Maxwell's team found.
Previous studies have not found a similar benefit from arginine supplementation, Dr. Richard O. Cannon III from the National Institutes of Health, Bethesda, Maryland, notes in a journal editorial. "The benefit of the medical food bar of Maxwell et al. to endothelial function, which is in contrast to the negative findings of studies…that used even higher daily doses of L-arginine, may be due to the ingredients in the bar other than L- arginine…that might enhance NO synthesis," he suggests.
"Clearly, more placebo-controlled clinical trials will be necessary to resolve the issue of L- arginine (and other active ingredients) as adjunctive therapy for ischemic heart disease and the mechanism of benefit, if real," Dr. Cannon concludes.
J Am Coll Cardiol 2002;39:37-48.
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