Changes in mineral status are associated with improvements in insulin sensitivity in obese patients following l-arginine supplementation

PURPOSE: The aim of this study is to evaluate the long-term influence of l-arginine intake on mineral concentration in patients with obesity and to assess the changes in lipid serum levels, fat content, and insulin resistance that result. METHODS: A randomized double-blind placebo-controlled study was conducted. 88 obese patients were randomly assigned to receive either 9 g of l-arginine or placebo daily, for 6 months. At baseline and after 6 months, selected anthropometrical measurements and blood biochemical analyses were performed and mineral levels were assessed. To assess insulin sensitivity, the gold-standard euglycemic clamp methodology was used. RESULTS: We found that 6 months of l-arginine supplementation resulted in significant increases in insulin sensitivity (Δ1.1 mg/kg/min, P < 0.01) and zinc levels (Δ1.5 μmol/L, P < 0.001). Moreover, a positive correlation between the change in zinc concentration in serum and the change in insulin sensitivity was observed (R = 0.80, P < 0.01). In the group of patients treated with l-arginine, a negative correlation between the change in zinc concentration in serum and the change in body fat content was noted (R = −0.38, P < 0.05). CONCLUSIONS: l-Arginine supplementation affects zinc status in obese patients. One beneficial influence is related to the improvements in insulin sensitivity.