ZMA (zinc monomethionine asparate and magnesium asparate) is a supplement that combines zinc, magnesium, vitamin B6 and asparate in a specific formula to aid in boosting testosterone levels and muscle recovery.

ZMA can boost testosterone production by up to 30%, strength by up to 11%, and improve muscle mass and recovery after exercise.  The basis for these claims is that the supplement corrects underlying zinc and/or magnesium deficiencies, thus normalizing various body processes and improving testosterone levels.  Zinc is needed for growth, cell production and testosterone production.  A zinc deficiency may reduce the body's anabolic hormone levels and adversely affect muscle mass and strength. Magnesium helps reduce levels of stress hormone cortisol (high levels are produced during periods of intense training), which would otherwise promote muscle breakdown.  A magnesium deficiency may increase catabolism.  ZMA supplements may therefore help increase anabolic hormone levels and keep high levels of cortisol at bay correcting a zinc and magnesium deficiency.