No effect of an L-arginine-enriched medical food (HeartBars) on endothelial function and platelet aggregation in subjects with hypercholesterolemia

Background Providing L-arginine as a precursor for nitric oxide has been proposed to improve endothelial function in populations at high risk for cardiovascular events. We studied the effects of dietary L-arginine supplementation with HeartBars (a medical food rich in L-arginine, Cooke Pharma, Belmont, Calif) on flow-mediated dilation and markers of endothelial function in subjects with hypercholesterolemia. Methods We randomly assigned 47 subjects with hypercholesterolemia to receive one HeartBar containing 3.3 g t-arginine each, or a placebo bar, consumed twice daily for 2 weeks. Flow-mediated dilation, platelet aggregation studies, and soluble levels of endothelial and platelet adhesion molecules were obtained before and after the 2-week treatment period. Results Baseline and follow-up levels of L-arginine were 78.5 +/- 28.2 mumol/L and 80.7 +/- 26.7 mumol/L, respectively (P = .54). The HeartBar group had no improvement in flow-mediated dilation; changes in brachial artery diameter at baseline and follow-up were 5.52% +/- 3.32% and 4.96 +/- 2.39%, respectively. There were also no changes in the soluble levels of E-selectin and P-selectin by treatment group. Conclusions In our study, 2 weeks of HeartBar supplementation in subjects with hypercholesterolemia showed no favorable effects on endothelial or platelet function.