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ZMA (zinc monomethionine aspartate, magnesium aspartate and vitamin B6) is a supplement used primarily by athletes, gymnasts, and bodybuilders. It was developed by Victor Conte (founder of BALCO Laboratories in Burlingame, California). No high quality scientific study has found it to have any beneficial effects on muscle building or strength, and the International Society of Sports Nutrition and the Australian Institute of Sport regard it as having no clear benefits.
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 because calcium blocks the absorption of zinc.
Since ZMA is not a patented formula, other manufacturers can produce supplements using the original ZMA formula. However, as ZMA is a registered trademark of SNAC Nutrition (SNAC Systems Inc.), other manufacturers can only brand a product as ZMA, or use the term in marketing, when they have been licensed to do so by SNAC Nutrition. A number of manufacturers take the original ZMA formula and seek to enhance it with added ingredients. 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. Like all 5-HTP-containing supplements, vivid dreams and/or nightmares are a recognized possible side effect within a subset of users.
All three basic components in ZMA formula are important in biological processes, and while studies have shown that most Americans get enough zinc and vitamin B6, more than 50% don't meet the U.S. government's recommendation for magnesium.
A 1998 study was undertaken on NCAA football players during an 8-week spring training program. The control group was told to cease taking any nutritional supplements. Those who took the ZMA tablets claimed greater increases in muscle strength. This study was funded by SNAC Systems Inc, the intellectual property right holder, and one of the study's authors, Victor Conte, has ownership equity in this company.
In 2004, a study funded by a research grant from Cytodyne (another supplement producing company) with 42 resistance trained males showed that ZMA supplementation had no significant effects on total and free testosterone, IGF-1, growth hormone, cortisol, the ratio of cortisol to testosterone, or muscle and liver enzymes in response to training. No significant effects were observed in changes in strength, upper or lower body muscle endurance, or anaerobic sprint capacity.
In another study done in 2006, a team of German scientists conducted a study on the effect of ZMA and testosterone levels in the body. The result showed an increase in zinc secretions in urine making it much darker like blood, but no effect on the level of testosterone in the body.
- "What Is ZMA?". WebMD. Retrieved 2018-03-25.
- "High dietary calcium intakes reduce zinc absorption and balance in humans". Retrieved 2016-03-01.
- "Ohio State University Extension Fact Sheet". Retrieved 2006-08-11.
- "More than half of Americans don't get nearly enough magnesium" (PDF). Retrieved 2006-08-11.
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