Vitamin B-6 further enhances absorption and utilization. ZMA is a powerful, 100% natural supplement that has been clinically proven to increase free testosterone, total testosterone and insulin-like growth factor (GF-1) levels. It also heightens muscle strength in training athletes without the use of steroids. Its synergistic combination of zinc, magnesium, and vitamin B-6 is designed to enhance muscle strength, endurance, healing and recovery after exercise. ZMA is the only such product validated by published research.