Magnesium or ZMA: What's the Difference

Magnesium is one of the most popular minerals among people who train, and ZMA is one of the best-known complexes in which magnesium is a component. Despite the similarity of the names on the labels, these are products with different logic: in the first case you choose a specific form and dose of magnesium, in the second you get a ready-made mixture with zinc and vitamin B6. The editors explain the difference.

The role of magnesium in the body

Magnesium takes part in hundreds of enzymatic reactions. The most important of them for an athlete is its work with ATP: in the cell the energy molecule actually functions as a complex with magnesium. Without it, muscle contraction, protein synthesis and nerve impulse transmission are impossible.

The mineral also regulates the work of ion channels, in particular blocking NMDA receptors at rest and affecting calcium channels. It is with this that its importance for neuromuscular excitability, muscle relaxation and, in part, sleep is associated.

The main part of magnesium is stored in bones and muscles, while less than one percent of the total reserves is in the blood serum. Because of this, a normal blood test does not always rule out a deficiency in the tissues.

The recommended intake of magnesium for adults is approximately 310-420 mg per day depending on sex and age. A person should get a significant part of this amount from food, and supplements only complement the diet.

Forms of magnesium in supplements

Standalone magnesium supplements are produced in many forms: oxide, citrate, glycinate (bisglycinate), malate, lactate, chloride, taurate, L-threonate. They differ in elemental magnesium content, solubility and effect on digestion.

Oxide contains a lot of elemental magnesium but is absorbed worse and more often acts as a laxative. Citrate is soluble and well absorbed, but in large doses it also loosens the stool. Glycinate is usually gentler on the intestine, so it is often chosen for evening intake.

The ability to choose the form is the key advantage of standalone magnesium. A person with sensitive digestion takes glycinate, a person prone to constipation takes citrate, and one for whom price matters takes the more affordable salts.

The dose of standalone magnesium is also easy to adjust: from 100-200 mg as a supplement to a good diet to larger amounts on a doctor's recommendation in the case of a confirmed deficiency.

How ZMA differs

ZMA is a ready-made combination in whose classic version magnesium is presented as aspartate in an amount of about 450 mg, zinc as mono-L-methionine and aspartate (about 30 mg), plus vitamin B6 (10-11 mg). The form of magnesium here is chosen for you.

The amount of magnesium in ZMA exceeds the recommended upper limit for supplements - 350 mg per day for adults. This limit is set precisely because of the risk of a laxative effect, not because of systemic toxicity, but it is worth taking into account.

Another difference is the interaction of the components. Studies of mineral balance have shown that very high doses of zinc can reduce the absorption of magnesium. At ZMA doses this effect is most likely small, but the very combination of two competing minerals in one capsule is not ideal from the standpoint of absorption.

So, the magnesium in ZMA is not a "better" magnesium, but simply one component in a fixed mixture that may be appropriate only under certain conditions.

The evidence base

For standalone magnesium there are randomized studies on sleep. Abbasi and colleagues (2012) reported an improvement in insomnia measures in elderly people who took magnesium. The systematic review by Mah and Pitre (2021) rated the quality of evidence as low, although the direction of the effect was favorable.

As for athletic performance, the data are mixed: reviews indicate that correcting a magnesium deficiency may improve performance, but in people with normal status additional magnesium provides no noticeable benefit.

For ZMA the key works concern hormones and strength. The initial positive study by Brilla and Conte (2000) was not confirmed by Wilborn and colleagues (2004), who found no effect on testosterone, IGF-1, body composition or strength.

Thus, magnesium has a modest but real evidence base for certain purposes, while ZMA as a combination is mainly a marketing story with one dubious positive study.

Safety and signs of deficiency

A magnesium deficiency can manifest as muscle cramps, twitches, fatigue, irritability and heart rhythm disturbances. However, these symptoms are nonspecific, so self-diagnosis based on them is unreliable.

The risk groups for deficiency are people with gastrointestinal diseases, type 2 diabetes, chronic alcohol use, as well as patients who take proton pump inhibitors or some diuretics for a long time.

• Do not take magnesium supplements without a doctor in chronic kidney disease.
• Separate the intake of magnesium and antibiotics of the tetracycline and fluoroquinolone classes.
• Take into account the magnesium in multivitamins and heartburn remedies.
• Loosening of the stool is a signal to reduce the dose or change the form.

With ZMA, questions about the safety of zinc are added: prolonged intake of doses exceeding the upper limit can cause a copper deficiency. Therefore the safety of the complex must be assessed by all its components, not just by magnesium.

Editorial conclusions

Magnesium and ZMA differ above all in the possibility of choice: standalone magnesium allows you to select the form and dose, while ZMA gives a fixed mixture with a high dose of magnesium, zinc and vitamin B6.

For supporting sleep and correcting a magnesium deficiency, a standalone product is usually the more precise tool. ZMA makes sense only when both minerals are needed.

The hormonal promises associated with ZMA are not confirmed by independent studies, so a product should be chosen according to real needs.

We also recommend our materials on the forms of magnesium, on comparing zinc and ZMA and on melatonin and magnesium for sleep.

References

1. de Baaij JH, Hoenderop JG, Bindels RJ. Magnesium in man: implications for health and disease. Physiol Rev. 2015;95(1):1–46.
2. Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: National Academy Press; 1997.
3. Abbasi B, Kimiagar M, Sadeghniiat K, et al. The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial. J Res Med Sci. 2012;17(12):1161–1169.
4. Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review & meta-analysis. BMC Complement Med Ther. 2021;21(1):125.
5. Nielsen FH, Lukaski HC. Update on the relationship between magnesium and exercise. Magnes Res. 2006;19(3):180–189.
6. Spencer H, Norris C, Williams D. Inhibitory effects of zinc on magnesium balance and magnesium absorption in man. J Am Coll Nutr. 1994;13(5):479–484.
7. Wilborn CD, Kerksick CM, Campbell BI, et al. Effects of zinc magnesium aspartate (ZMA) supplementation on training adaptations and markers of anabolism and catabolism. J Int Soc Sports Nutr. 2004;1(2):12–20.