ZMA is a proprietary trademark blend, developed by Victor Conte of Balco Labs, based on research studies. It was developed to increase testosterone and muscular strength.

How ZMA works

ZMA is zinc, magnesium and B6. Zinc appears to have a strong role in regulating testosterone levels, by blocking the conversion of testosterone to DHT, through the 5A Reductase enzyme. Magnesium is a important neurological mineral and has been shown in past studies to improve strength. Vitamin B6 helps with zinc’s inhibitory action on the 5A reductase enzyme.

ZMA Studies

The original study on ZMA was founded by the Victor Conte. He had NCAA football athletes stop taking nutritional supplements for 8 weeks. The control group took ZMA and their lean muscle, strength, and serum testosterone levels were monitored. ZMA supplementation iincreased the leg strength by 11.5% over 4.9% of the placebo. There was an increase of 30% in free and total testosterone (vs 10% in the placebo), and an increase of 20% in IGF-1 levels (vs a 20% decrease in placebo). Results of the study did not show any changes in lean muscle gains despite the anabolic changes.

A study published in (Journal of the International Society of Sports Nutrition 1 (2): 12-20. doi:10.1186/1550-2783-1-2-12) showed no significant differences were observed between groups in anabolic or catabolic hormone status, body composition, 1-RM bench press and leg press, upper or lower body muscular endurance, or cycling anaerobic capacity during 8 weeks of ZMA supplementation.

A recent ZMA study published in (European Journal of Clinical Nutrition advance online publication, 19 September 2007; doi:10.1038/sj.ejcn.1602899) 14 subjects in their 20s through 30’s excercised regularly and took 11 to 22 mg of zinc a day, before the study started. When the study started, they took the recommended doses of ZMA and measured their urine for testosterone and other metabolites and their serum testosterone levels. Results showed no difference in free or total testosterone serum levels or in changes in urine excretion patterns of testosterone and it’s metabolites. Serum zinc levels and excretion in urine were heightened.

Conclusion:

The only study that shows ZMA works, was the original funded by the developer of ZMA. ZMA probably only works if you are deficient in magnesium or zinc. Zinc appears to be excreted after excercise, so bodybuilders may require slightly more to offset their active lifestyle. This doesn’t point to the efficacy of ZMA as being anything special, just that some may benefit from ZMA because they are already deficient. If you have a really good multi-vitamin with a easily absorbable form of zinc (something other than zinc oxide), it should be adequate zinc intake.