Antioxidant supplementation in vitro does not improve human sperm motility.

To determine the effects of supplementation of preparation media with ascorbate and alpha-tocopherol on subsequent sperm motility and reactive oxygen species production. Prospective study to analyze postpreparation human sperm motility parameters and reactive oxygen species production following antioxidant supplementation. Andrology Laboratory, Royal Maternity Hospital, Belfast, Northern Ireland. Sixty patients attending the Andrology Laboratory for semen analysis. Normozoospermic and asthenozoospermic semen samples (n = 10 for each control and antioxidant group) were prepared by Percoll density centrifugation (95%-47.5%) in media supplemented with ascorbate or alpha-tocopherol to different concentrations within physiologic levels. Controls were included that were not exposed to antioxidant. Sperm motility parameters were assessed using computer-assisted semen analysis. The generation of reactive oxygen species was determined using luminol-dependent chemiluminescence. The production of reactive oxygen species by sperm was reduced by supplementation in vitro with ascorbate and alpha-tocopherol. However, progressive motility, average path velocity, curvilinear velocity, straight-line velocity, and linearity were decreased significantly, with the greatest inhibition observed with the highest concentrations of antioxidants. Supplementation of preparation media with ascorbate and alpha-tocopherol, either singly or in combination, is not beneficial to sperm motility.