Medium-term effect of sublingual L-glutathione supplementation on flow-mediated dilation in subjects with cardiovascular risk factors

Objective: Supplementation of GSH may be a positive strategy to improve the endogenous antioxidant defense required to counteract many acute and chronic diseases. However, the efficacy of GSH treatment seems to be closely related to type of administration, degree of its absorption and increase of its concentrations. We tested a new sublingual formulation of L-GSH, which enter directly the systemic circulation, to assess its efficacy on circulating biochemical markers of hepatic metabolism, lipid profile and oxidative stress and on peripheral vascular function compared to placebo in subjects with cardiovascular risk factors (CVRF). Methods: Sixteen healthy male subjects with CVRF were enrolled in a double-blind randomized placebo-controlled cross-over study. At each visit, blood samples were collected for biochemistry analyses and peripheral endothelial function (RHI) and stiffness were measured by Endo-PAT2000. Results: In the overall population a decrease in total and LDL-cholesterol was highlighted after L-GSH supplementation compared to placebo (p = 0.023 and p = 0.04, respectively). On the contrary, no difference was observed in RHI and oxidative stress markers between L-GSH and placebo in our population. However seven subjects with baseline abnormal RHI (≤1.67) compared to those with normal RHI showed a significant reduction of arterial stiffness after L-GSH administration, (p =0.007 and p = 0.037, respectively). Conclusions: Supplementation of L-GSH compared to placebo influences the lipid profile of subjects with CVRF. Sublingual L-GSH may represent a valid prevention of vascular damage in CVRF subjects with endothelial dysfunction.