Previous research has demonstrated the benefits of anti-oxidant treatment in the prevention of hearing loss in animals. Our study tested the effects of an undenatured whey protein supplement rich in glutathione on human patients with hearing loss. Over an average of 36 months, 30 patients with hearing loss and who had data sufficient for analysis were treated with a glutathione supplement and were compared with 30 retrospective controls selected from the same otologic patient population. Patients were followed using regular hearing tests. Linear regression analysis was used to determine whether study group, baseline audiometric score, time followed, and autoimmune etiology modified the rate of hearing loss. Treatment with the glutathione supplement failed to modify significantly the progression of hearing loss in the treated population. The baseline audiometric score was most predictive of the final audiometric score (p < 0.0005). Although glutathione supplementation was not shown to be helpful in slowing hearing loss in the patients studied, our research model proved valid as it demonstrated an overall decline in hearing in both the treated and control groups over time of sufficient magnitude to permit detection of a treatment effect if a substantial effect had occurred. We suggest that this model be applied to future studies investigating the effects of antioxidants on hearing loss.