ZMA A testosterone booster that actually works?

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ZMA (Zinc Monomethionine Asparate) has been on the market for several decades and is still going strong. The patented combination of zincmagnesium and vitamin B6 is known as a testosterone booster and sleep aid. Although it would also give you weird dreams. What’s true?

The main points:

1.   ZMA is a combination of Zinc Monomethionine and Aspartate (30mg), Magnesium Aspartate (450mg) and Vitamin B6 (10.5mg).

2.   Zinc, magnesium and vitamin B6 are important micronutrients for energy, muscle protein synthesis and hormones, among other things.

3.   According to its creator, supplementation with ZMA promotes testosterone levels and strength performance, and therefore muscle growth.

4.   Two independent studies have disproved these claims: ZMA is only effective if there is a shortage of one or more of the ingredients. It is therefore not a testosterone booster, but a support supplement.

5.   The fact that many strength athletes say they have had positive experiences with ZMA may be because strength athletes are more likely to have a deficiency of zinc, magnesium and/or vitamin B6. In addition, there may be a synergy between the ingredients when taken together in these proportions. However, this has not been scientifically proven.

6.   Due to the large amount of magnesium it contains, ZMA can also have a positive effect on sleep, but probably only if you are deficient in magnesium.

7.   Supplements with zinc, magnesium and vitamin B6 can be useful if you combine intensive exercise with a calorie-restricted diet, such as during the cut. A one-sided or unhealthy diet can also cause a deficiency. ZMA is then a useful support supplement, although the ingredients are also available as separate supplements or as part of a multivitamin.


ZMA was conceived in the early 1990s by American supplement guru Victor Conte, founder and president of Bay Area Laboratory Co-operative (BALCO), a California sports nutrition center.

The original patented formula of the strength sports supplement was as follows:

  • 30 mg zinc (monomethionine and aspartate)
  • 450mg magnesium aspartate
  • 10.5mg vitamin B6

Conte claimed that this combination of ingredients increases levels of testosterone and IGF-1, two hormones that play an important role in muscle strength and mass. He substantiated this with his own research at Western Washington University in 2000. In it we see increases of 30% in testosterone and 20% in IGF-1 i ] . Not exactly an objective study, as you will understand.

Conte proved to be a shrewd marketer and quickly turned ZMA into a bestseller. But there was a dark edge to that clever marketing. Conte found a number of well-known American athletes willing to promote ZMA in advertising campaigns. Except in the ‘innocent’ ZMA, Conte also acted in illegal doping. And those same athletes later turned out to be Conte’s loyal customers… The scandal came to light in 2005 and Conte was jailed for several months. His reputation and that of the athletes involved had been damaged. ZMA’s, remarkably, not very much.

ZMA is of course not doping either; actually it’s little more than a stripped-down multivitamin. The results of Contes’ study of his own supplement were quashed in 2004 by researchers at Baylor University. They concluded that supplementation with ZMA has no effect on hormone levels, nor on strength during strength training, as long as you get enough zinc, magnesium and vitamin B6 through your diet ii ] . A more recent study, from 2018, led to the same conclusion iii ] . From this perspective, ZMA is not a testosterone booster, but a support supplement.


Nevertheless, ZMA is still a popular supplement among bodybuilders to this day. And on the web you can read many positive user experiences, although they are often also about beneficial effects on sleep. And sleeping well is also important for your gains.

Do all those users have a shortage of one or more of the ingredients, so that supplementation has an effect? Or is it mainly the synergy of the ingredients that gives something extra? Or just a placebo effect? Let’s briefly review the composition of ZMA.


Zinc is an important mineral that is involved in, among other things, the construction of proteins, the growth and development of tissue, and the proper functioning of the immune/immune system.

The average person should get about 10 milligrams of zinc each day. Normally, this can be achieved through food without any problems: zinc is found in small amounts in many different foods, such as meat, dairy products, grain products, nuts and shellfish such as shrimp and mussels. A significant zinc deficiency or excess is rare.

However, bodybuilders need more zinc because of its role in muscle protein synthesis and thus muscle repair and growth. In addition, zinc has a protective function for existing muscle mass. With a normal, not too one-sided diet and certainly in bulk, you as a bodybuilder probably get more than enough zinc. During the cut, however, zinc supplementation can sometimes be necessary, especially if there is a long-term energy deficit and/or a lot of cardio. Vegetarians and vegans also often need zinc supplementation.

The recommended dose of zinc supplements for adults is 15 to 30 milligrams per day. The upper limit for total zinc intake is 40 milligrams per day.

Zinc supplements only function as a testosterone booster in cases of zinc deficiency and/or unusually low testosterone levels. With sufficient zinc and normal testosterone levels, there is probably no noticeable effect.


Magnesium is one of the most important minerals in our body. It is involved in numerous processes, including the proper functioning of the muscles. A magnesium deficiency results in stiff muscles and cramps. A deficiency also leads to fatigue and can negatively affect your sleep. Matters that can be at the expense of performance during strength training. Strength athletes therefore need more magnesium than non-active people, who must consume 300 to 400 milligrams of the mineral daily.

Fortunately, magnesium is found in many foods that you consume every day, such as whole wheat bread and other whole grain products, vegetables, nuts, milk and milk products and meat. You will therefore not soon have a shortage, especially if you are in the bulk as a bodybuilder.

The risk of a (small) magnesium deficiency is real if you follow a long-term calorie-restricting diet as an athlete, for example as a bodybuilder in the cut. In that case, err on the side of caution by taking a magnesium supplement. The maximum dose is 250 milligrams per day.

Take a supplement with a magnesium compound that guarantees high absorption: magnesium citrate, malate, taurate, glycinate, lactate or gluconate. Avoid the poorly absorbable magnesium sulfate and oxide.


Vitamin B6 (pyridoxine) is important for metabolism (especially for the breakdown and construction of amino acids), the functioning of certain hormones, and for growth, blood production and proper functioning of the immune system and nervous system. The vitamin is found in meat, eggs, fish, nuts, bread and grain products, milk and milk products, cheese, legumes and vegetables.

The recommended dietary allowance (RDA) of vitamin B6 for adults is 1.5 milligrams per day. Strength athletes may need more vitamin B6: on the one hand for energy supply, on the other for muscle protein synthesis. Again, with a versatile diet with a calorie surplus you probably get more than enough. In the case of a calorie deficit in combination with intensive sports, such as in the cut, supplementation may sometimes be necessary. Since this also applies to other vitamins, a multivitamin is often a handy and cheap solution.

Vitamin B6 affects testosterone levels both directly and indirectly. Vitamin B6 supplementation is unlikely to increase testosterone in healthy individuals (not even as part of the ZMA supplement), unless there is a major vitamin B6 deficiency.

The tolerable upper limit of vitamin B6 in Europe has been set at 25 milligrams per day for adults.


It is evident that the three components of ZMA are important for all kinds of processes in the body. Moreover, these are three micronutrients that play a significant role in energy, muscle protein synthesis and the production of testosterone, which are important for strength athletes/bodybuilders. But that doesn’t make ZMA a testosterone or strength booster.


Although zinc, magnesium and vitamin B6 work together in many areas in the body, it is questionable whether and to what extent they reinforce each other if you take them together from one supplement. Zinc is known to be able to inhibit the enzyme 5alpha reductase in the conversion of testosterone to dihydrotestosterone (DHT) iv ] . Normally, the levels of zinc in the body are too limited to fulfill that role, but vitamin B6 can enhance zinc in that role. Taking both zinc and vitamin B6 in sufficiently high doses could increase testosterone levels at the expense of DHT iv ]. The aforementioned independent studies from 2004 and 2018 showed no testosterone-boosting effect in individuals who have sufficient zinc and vitamin B6 in their bodies ii ][ iii ] .


How is it possible that so many strength athletes annex bodybuilders say they have had positive experiences with ZMA? Well, perhaps many do not get enough zinc, magnesium and/or vitamin B6, all the more because strength athletes have a greater need for these micronutrients. If you do a lot of intensive sport, while you have a fairly unhealthy or one-sided diet, it is quite conceivable that a deficiency will arise. Especially on a calorie-restricted diet. Perhaps not a deficiency that is directly harmful to health, but enough to, for example, lower the testosterone level. If you then start supplementing with ZMA, it is quite possible that you will notice something.

However, do not forget that the use of supplements such as ZMA often also involves a placebo effect.


But why ZMA when you can also use a multivitamin or individual supplements? After all, these are also ways to get zinc, magnesium and vitamin B6, and usually cheaper than ZMA. But in most multivitamins, these ingredients, especially magnesium, are fairly low in doses. In addition, ZMA contains specific compounds of zinc (namely monomethionine asparate) and magnesium (asparate) and the ingredients are dosed in a certain ratio to each other.

It is unclear whether these properties of the formula do indeed contribute to the claimed effects. In addition, most ZMA clones contain different compounds and dosages than those in the original formula. Other connections are probably also sufficient, although not all. For example, zinc sulphate, magnesium sulphate and magnesium oxide are poorly absorbed by the body.


ZMA users often mention positive effects on sleep. This is mainly due to the presence of magnesium.

Magnesium regulates the so-called neurotransmitters, which send signals through the nervous system and the brain. The mineral also regulates the hormone melatonin, which plays a role in your body’s sleep-wake rhythm. Finally, magnesium binds to gamma-aminobutyric acid (GABA) receptors, neurotransmitters responsible for calming nerve activity. It’s the same neurotransmitter used by certain sleep medications.

A magnesium supplement can only help you sleep better if you have a magnesium deficiency v ] . On the other hand, magnesium in ZMA is dosed so high that it may also have some effect if you already get enough magnesium from food. Or is it again the interaction with the other ingredients? Because zinc may also have a beneficial effect on sleep vi ] . It continues to speculate at this point.


ZMA users also sometimes report that the supplement causes “weird, vivid dreams.” Something that again cannot be substantiated with direct research. It is possible that vitamin B6 can indeed influence dreaming, but then there must already be an extreme dose (250 mg) vii ] . But it cannot be ruled out that magnesium enhances the effect of vitamin B6 at this point and the effect on dreams therefore already occurs at lower doses vii ] . Experience it for yourself, we would say.


According to the original ZMA formula, you should take 30 mg of zinc, 450 mg of magnesium and 10.5 mg of vitamin B6. Many ZMA products are dosed lower, although you can of course take more capsules. However, it does not hurt to start with a lower dose and see how you react to it. After all, remember that the average person only needs 10 mg of zinc, 350 mg of magnesium and 1.5 mg of vitamin B6.

Although athletes need more of these micronutrients, the magnesium dosage in ZMA is very high. According to the Nutrition Center, you should supplement no more than 250 mg per day (on top of your magnesium intake from food) viii ] , while other sources use 350 mg as an upper limit ix ] . Higher intakes can cause intestinal complaints such as diarrhea.

An upper limit of 40 mg applies to the total intake of zinc. Due to the interaction with copper, that mineral can be deficient if you consume more zinc.

Supplements may not contain more than 21 mg of vitamin B6, according to the Nutrition Center. Prolonged overdose may cause peripheral neuropathy. This is a nervous system disorder that can cause numbness, tingling, or severe nerve pain in the hands and feet x ] .

If you want to stick to the original composition of ZMA as much as possible, then at least ensure the following proportions:

  • zinc: 6%
  • magnesium: 92%
  • vitamin B6: 2%


Because of the possible effect on sleep, it is usually recommended to take ZMA about an hour before sleep, preferably on an empty stomach for optimal absorption of the ingredients.

In addition, for best results, you should not take ZMA with dairy products or calcium-containing supplements. Minerals have the property that they compete with each other. If you take large amounts of magnesium and calcium at the same time, the absorption of one mineral can be at the expense of the other.


Although ZMA is touted as a testosterone booster, it is probably primarily a support supplement. Only if you are deficient in one or more of the ingredients – zinc, magnesium and vitamin B6 – will supplementation possibly have effects, including increasing testosterone levels.

Normally, a bulk bodybuilder should be able to get enough vitamins and minerals, despite his increased need for those micronutrients. If this is not the case, there is probably an unhealthy and/or one-sided diet or excessive exercise.

During a calorie-restricted diet in combination with intensive exercise, a micronutrient deficiency is real and ZMA can offer a solution. Besides the testosterone level, zinc, magnesium and vitamin B6 also influence other processes that are important for the strength athlete, such as energy supply, muscle protein synthesis and sleep.

In principle, you can also take zinc, magnesium and vitamin B6 as separate supplements, or, for example, in the form of a multivitamin. But the high doses, synergy of the ingredients and the specific compounds (in the original formula zinc monomethionine aspartate and magnesium aspartate) mean that ZMA is perhaps more than the sum of its parts. Although that possibility is still based on ‘anecdotal evidence’ alone and lacks the scientific basis. And much of that anecdotal evidence may be traced back to a placebo effect, fueled by the clever and dubious marketing of ZMA creator Victor Conte.


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