Updated January 23, 2024. Weight lifters and bodybuilders tout ZMA, a well-known sports performance supplement, for its ability to raise testosterone and other anabolic hormones, and some claim it improves muscle strength too. Others take this vitamin and mineral supplement to improve the quality of their sleep and aid with muscle recovery after intense exercise. Despite all being well and good and setting aside testimonials, the question arises: Does ZMA genuinely deliver results? And if it does, are there any side effects or contraindications? Fortunately, clinical research has been conducted on this sports supplement.
What Is ZMA
ZMA is a proprietary blend of vitamin B6, magnesium, and zinc. Three capsules of contain the following nutrients:
| Men's Formula | Women's Formula | |
| Vitamin B6 | 105 mg (618% DV) | 7 mg (412% DV) |
| Magnesium (aspartate & Oxide) | 450 mg (107% DV) | 300 mg (71% DV) |
| Zinc (Mono-L-Methionine, Aspartate & Oxide) | 30 mg (273% DV) | 20 mg (182% DV) |
There is both a men's and women's formula however clinical research involving the woman's ZMA supplement could be located.
How Do You Take ZMA?
The company recommends men take 3 capsules a day, 30-60 minutes before bedtime on an empty stomach. For women, take two capsules on an empty stomach 30-60 minutes before going to bed. For the best results, avoid taking it alongside foods or supplements containing calcium.
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ZMA Clinical Research
Study 1
The first study of this popular supplement involved 27 college football players who were instructed to take ZMA supplements or a placebo each day for 8 weeks. 3-day diet analysis revealed the football players were not deficient in zinc, magnesium, and vitamin B6 and actually exceeded the RDA for these nutrients. It was reported that ZMA vitamin and mineral supplements significantly raised the anabolic hormone profile of the athletes, including total testosterone, free testosterone, and IGF-1. To see the before and after levels, watch the video. In contrast, these hormone levels actually declined in placebo-takers.
An additional finding was that ZMA supplements also improved muscle power in the quadriceps and hamstrings (thigh muscles) too. In theory,
this might improve football game performance.
One possible criticism, however, was that the study was funded by SNAC, the company that makes ZMA supplements. Victor Conte, one of the researchers in the investigation, is the founder of SNAC. The acronym SNAC stands for Scientific Nutrition for Advanced Conditioning.
Study 2
In an attempt to shed light on the original findings, other researchers recruited 42 men and gave them ZMA supplements or a placebo, and instructed them to take the capsules before going to bed each night for 8 weeks. During that time, the men also performed a progressive strength training program. These investigators reported that the vitamin and mineral supplement did not raise total or free testosterone or IGF-1 levels. Likewise, there were no significant improvements in muscle strength either.
A major drawback to this study, however, was that it did not used a dietary supplement called Z-Mass instead of the original ZMA formula. While the Z-Mass supplement contained similar amounts of vitamin B6, zinc, and magnesium, it also contained additional ingredients such as L-Dopa, potassium, and Mucuna pruriens (velvet bean), which, in theory, may have interfered with the results.
Study 3
In another clinical investigation, 14 healthy, weight-trained men with normal to high blood levels of zinc were given ZMA supplements or a placebo for 56 days and instructed to follow their usual strength training program. While the supplement did raise zinc levels, it proved ineffective at boosting free or total testosterone levels.
Study 4
Researchers in Iran recruited 12 young male weightlifters who were given placebos or ZMA supplements. After seven weeks of weightlifting training, the supplements proved ineffective at raising total or free testosterone levels or reducing cortisol. Additionally, both groups gained similar improvements in strength from the exercise program.
Summary of ZMA Testosterone Research
| Amount of Zinc | Amount of Magnesium | Amount of Vit B6 | Raised Testosterone | |
| Brilla LR et al. 2000 | 30 mg | 450 mg | 10.5 mg | Yes |
| Wlborn C et al. (2004) | 30 mg | 450 mg | 11 mg | No |
| Koehler K et al. (2009) | 30 mg | 450 mg | 10.5 mg | No |
| Moezzi N et al. (2013) | 30 mg | 450 mg | 10.5 mg | No |
Can ZMA Help You Sleep Better?
Because both zinc and magnesium play a role in central nervous system regulation and muscle contractions, this combination of supplements is popular with athletics attempting to battle insomina and maximize recovery. When researchers gave sleep-deprived men the ZMA, the supplement stack failed to improve sleep quality or weight-lifting performance.
No studies were located that specifically tested whether this supplement improves the quality of sleep (REM sleep, delta wave, etc) or aids with muscle recovery following intense exercise. So far no investigators have tested whether the supplement works better when cycled. In other words, if people periodically stop taking it for a few weeks.
What Does ZMA-5 Do?
The ZMA-5 supplement is touted as “the next generation.” This supplement gets its name from 5-HTP, a metabolite of the amino acid tryptophan. ZMA-5 contains the same amounts of magnesium, zinc, and vitamin B6 as the original formula but, in addition, also has 50 mg of 5 HTP and 100 mcg of folic acid. Bioperine (black pepper extract) is also added to enhance nutrient absorption. Some studies show that 5-HTP may help with sleep, weight loss, and depression.
How They Compare To Each Other
| ZMA-5 | Original (men's formula) | |
| Vitamin B6 | 10.5 mg | 10.5 mg |
| Folic acid | 100 mcg | – |
| Magnesium | 450 mg | 450 mg |
| Zinc | 30 mg | 30 mg |
| 5-HTP | 50 mg | – |
| Bioperine (black pepper extract) | 5 mg | – |
No studies could be located comparing the effects of ZMA-5 to the original formula.
ZMA Side Effects and Cautions
The supplement has been available for many years and is likely safe for at least two months of use in healthy people, which was the duration of the studies summarized above. General guidelines to reduce the chances of adverse side effects include:
General Suggestions
- Start with less-than-recommended. Give your body time to adjust.
- Avoid this if you are pregnant/breastfeeding until speaking with your physician.
- Cease taking it at least two weeks before having surgery, including dental surgery.
- Speak to your doctor/pharmacist if you take any medications.
- Magnesium can cause diarrhea at doses above 350 mg
ZMA Customer Endorsements
While not confirmed by research, some testimonials report the following:
- Improved sleep
- Reduced Aggression
- Enhanced libido
Other Considerations
- In one of the ZMA clinical studies, people's urine became more alkaline, and their urine output almost doubled.
- Taking more than 1000 mg of vitamin B6 can irritate nerves, causing feelings of pins and needles (called paresthesia). Thus, look at the amount of B6 in other sports supplements you take.
- Vitamin B6 might reduce folic acid levels.
- Some research finds people taking 50 mg/day of zinc had higher harmful LDL cholesterol levels.
Verdict: Does ZMA Boost Testosterone?
The original clinical trial indicated this vitamin and mineral combination raised anabolic hormone levels and strength. However, subsequent experiments have failed to replicate those findings. Thus far, the hormone-boosting effects of this supplement in women appear to be lacking.
there was no mention on whether they test the zinc and magnesium levels in the first study were they tested pre/post study? since low levels of zinc and magnesium decrease testosterone in the body I would think that would be an important thing to test for. The second study they said the levels were tested and normal; so it makes sense that taking more of something that you are not deficient in would not have much of an impact
April, good call. I re-read the first study (the original ZMA study) and the football players’ intake of zinc, magnesium, and vitamin B6 was higher than the RDA so they were not deficient. I have corrected this and added it to the review.