ZMA has often been purported as a testosterone booster, and while that claim hasn’t always been proven, ZMA has several other benefits that may boost recovery and immune function for athletes and bodybuilders. Pick a formulation that has at least 30mg zinc, 500mg magnesium, and 10mg vitamin B6. Some individuals will find it most useful to use this supplement before bed as it may improve sleep quality!
Reference: Moëzzi, N., Peeri, M., & Matin, H. (2013). Effects of zinc, magnesium and vitamin B6 supplementation on hormones and performance in weightlifters. Annals of Biological research, 4, 163-168.