ZMA® ('Zinc monomethionine and aspartate and Magnesium Aspartate) is a supplement used by bodybuilders and athletes. It was developed by Victor Conte (founder of BALCO Laboratories in Burlingame, California) and is a combination of zinc, magnesium and vitamin B6. ZMA claims to raise strength levels, though independent studies do not support this claim.

The original ZMA formula is composed of zinc monomethionine and aspartate (30 mg), magnesium aspartate (450 mg), and vitamin B6 as pyridoxine hydrochloride (10.5 mg). According to the label directions, ZMA should be taken 30 - 60 minutes prior to bedtime and on an empty stomach to help synchronise absorption with sleep. Also, the product should not be taken with foods or supplements containing calcium for calcium blocks the absorption of zinc.

Since ZMA is a registered trademark of SNAC Nutrition (SNAC Systems Inc.) but not a patented formula, other manufacturers using the abbreviation for their products may introduce various formulae with different chelated or other compounds (such as citrate, gluconate, and oxide) of basic components (i.e. zinc, magnesium, and vitamin B6), additional ingredients (such as copper, melatonin, fenugreek,tribulus terrestris, vulgara suma, and mucuna pruriens)of properties supposedly synergistic with basic components, and different proportions. Nevertheless, some manufacturers market products of a similar basic formula but do not use the trademark ZMA abbreviation.Furthermore, SNAC Nutrition itself has ZMA-5 (ZMA formula with 5-Hydroxytryptophan) marketed as a sleep enhancer and ZMA Nightcap (ZMA-based proprietary blend with 5-Hydroxytryptophan) marketed as an anabolic mineral support.