Do ZMA supplements really work?
The ZMA supplement - also known as zinc magnesium aspartate - is used by people looking to improve their sleep and also by fitness enthusiasts who want to build muscle and increase their stamina. Yet there is little evidence to support the use of ZMA in individuals who aren't nutrient deficient. The best way to absorb and benefit from the nutrients in ZMA is to eat a healthy, well-balanced diet.
What is ZMA?
"Zinc magnesium aspartate (ZMA) is a natural supplement containing three ingredients - zinc, magnesium aspartate, and vitamin B6," says Dr Deborah Lee at Dr Fox Online Pharmacy.
ZMA supplementation is becoming particularly popular among athletes and fitness enthusiasts looking to improve muscle growth, stamina, and recovery from intense exercise. The trouble is, there is very little scientific evidence to back the claims made by ZMA supplement manufacturers.
What are the benefits of ZMA?
While studies on ZMA are scarce, the benefits of the ZMA's ingredients are well documented. Our bodies absorb and benefit from the natural sources of zinc, magnesium, and vitamin B6 we get through our diet. These substances each play an instrumental role in our health.
"Zinc is an essential trace metal that's vital for a range of physiological and biochemical processes. It is a co-factor for the production of over 300 enzymes and 1,000 transcription factors (proteins that transcribe DNA)," says Lee. The NHS recommends that men aged 19-64 years need 9.5 milligrams (mg) a day and women 7 mg a day.
- A healthy immune system.
- Muscle health.
- Wound healing.
- Building the proteins and molecules which are the basis of all our cells.
- Improved taste and smell, and good vision.
A mineral that is involved in over 600 enzyme reactions.
- A healthy immune system.
- Muscle health.
- Regulating blood pressure.
- Nerve function.
- Sleep may improve.
Also known as pyridoxine, this vitamin is needed in over 100 enzyme reactions.
- A healthy immune system.
- Nutrient metabolism.
- Cognitive development.
- Mood regulation.
- Energy metabolism.
- Healthy circulation.
The headline benefits of ZMA supplementation are as follows:
- Enhanced muscle growth and strength.
- Better endurance during exercise and faster recovery post-exercise.
- Improved sleep quality.
The importance of diet
It's important to note that consuming a diet rich in these nutrients is more important and beneficial than any supplement you can take, including ZMA supplements. Our food is our main source of zinc, magnesium, and vitamin B6, and a poor diet can put us at risk of nutrient deficiency. Consequently, diet is a much more significant factor when it comes to all the health benefits advertised on ZMA supplement labels.
"Your body is primed to absorb nutrients from natural foods, far better than from oral supplements," cautions Lee.
- Dietary sources of zinc: meat, shellfish, legumes, nuts, whole grains, dairy, eggs.
- Dietary sources of magnesium: leafy green vegetables, legumes, nuts, whole grains, fatty fish, bananas.
- Dietary sources of vitamin B6: leafy green vegetables, bananas, chicken, fish, fortified cereals.
Does ZMA enhance sports performance?
Put simply, there's little to no evidence to support claims that ZMA improves muscle growth and athletic performance in individuals with healthy zinc and magnesium levels.
Very few studies have looked at the effects of the ZMA supplement. Therefore, these supposed benefits are purely theoretical because the only solid research is based on individual zinc and magnesium supplementation.
Of this research, improvements to sports performance have only been observed in people with zinc deficiency or magnesium deficiency (insufficient levels of these minerals).
Some experts theorise that these deficiencies are more common among athletes and fitness enthusiasts, possibly due to the loss of zinc and magnesium through sweating and also the increased likelihood of following a restrictive diet.
As food is the most important source of zinc and magnesium, the most effective way to ensure you maintain healthy levels is to follow a healthy, nutrient-rich diet.
Does ZMA increase testosterone?
A deficiency in either zinc or magnesium may result in lower levels of testosterone. Higher levels of this male sex hormone are associated with an increase in lean muscle mass, less fat, and enhanced sports performance.
While zinc supplements may boost testosterone levels in those with zinc deficiency, this doesn't appear to apply to healthy individuals.
As such, several ZMA studies carried out on people with adequate zinc levels found that the supplement did not raise testosterone levels or improve muscle mass and exercise performance.
Does ZMA help sleep?
Lee points out that as there are no studies that specifically investigate the effects of ZMA supplements on sleep, we can only draw conclusions from looking at studies of sleep and the individual constituents.
Sleep and zinc
"Recent research has demonstrated that low levels of zinc can contribute to poor sleep and that zinc supplementation may lead to improvements," says Lee. "Scientists have discovered that zinc has many integral roles that may explain its effects on sleep. Some types of brain neurons are filled with vesicles containing zinc, and the local release of zinc affects the function of a range of brain receptors and other neurotransmitters.
"There is no doubt that sleeping and eating bear a close relationship. In one study of 120 healthy individuals, the group that consumed zinc-rich food took less time to fall asleep and showed improved sleep efficiency."
Sleep and magnesium
The role of magnesium in sleep is not yet fully understood by scientists. However, it does appear to play an important role in calming brain activity, which may help our bodies prepare for sleep. Lee explains:
"Magnesium is thought to stimulate the GABA pathway - the pathway in the brain responsible for calming excitatory neurons (in other words, calming the brain). It also blocks N-methyl-D-aspartate (NMDA) receptors, again damping down excitatory brain activity.
"A 2012 study showed that magnesium supplements could significantly improve the time taken to fall asleep, sleep efficiency, and increased melatonin (the "sleepy hormone") and lowered cortisol (the "stress hormone") in people with insomnia."
Sleep and vitamin B6
"Low levels of vitamin B6 are linked to depression and poor sleep. This may be explained by the fact that vitamin B6 is needed in the production of the hormones serotonin and melatonin," says Lee. These hormones play an important role in regulating sleep.
Are ZMA supplements safe?
There have been no reports of major side effects from the ZMA supplement. However, taking ZMA more frequently than the recommended manufacturer dosages could lead to health issues.
Too much zinc
- Could cause nausea, diarrhoea, vomiting, abdominal cramps, loss of appetite, and headaches.
- Taking over 150-450 milligrams (mg) of zinc per day can also cause long-term problems, including reduced immune system function and clogged arteries (blood vessels).
Too much magnesium
- Can lead to nausea, diarrhoea, and abdominal cramps.
- While very rare, taking significantly more magnesium than recommended in supplements can lead to serious problems such as cardiac arrest and irregular heartbeat.
Too much vitamin B6
- May result in nausea, heartburn, sensitivity to light, painful skin disfigurations.
- In the long term, high doses may cause nerve damage.
It's also worth noting that zinc and magnesium supplements may affect certain medications. This includes antibiotics, blood pressure medicine, and diuretics (water pills).
Is ZMA good for females?
Some people have questioned whether ZMA is safe for females, due to the claims that this supplement promotes testosterone production. As we have seen, there is little evidence that ZMA boosts testosterone where zinc or magnesium levels are already healthy - this applies to both women and men.
It's also a common misconception that women don't have testosterone. It may be known as the male sex hormone, but women produce testosterone in lower levels in their ovaries, in adrenal glands (on top of the kidneys), and in certain tissues. Low testosterone levels in women (below 20 nanograms per decilitre in women aged 50 and above) can be a cause of muscle weakness and tiredness, just as it can in men.
How much ZMA should I take?
Always read the label for the recommended dose. For most brands, ZMA contains around:
- Three times the recommended daily dose of zinc - 30 mg.
- The recommended daily dose of magnesium - 450 mg.
- 10 times the recommended daily dose of vitamin B6 - 11 mg.
While zinc and vitamin B6 doses usually exceed the recommended daily allowance, these levels are generally considered safe to take. Most labels recommended a slightly smaller dose for women (usually two capsules or scoops of powder as opposed to three for men) for the same ratio of ingredients.
When to take ZMA
You will find that most ZMA supplement labels advise taking ZMA around 30-60 minutes before bed. This helps to align your supplementation with your sleep schedule.
In order to prevent the zinc from competing for absorption with any calcium in your system, it's not recommended that you eat or drink anything containing calcium before taking ZMA. Research shows that zinc may decrease the absorption of calcium into the intestines.
Does ZMA actually work?
More research is needed on the effects of the ZMA supplement on muscle mass, endurance, and sleep quality. However, as Lee points out, its individual components zinc, magnesium, and vitamin B6 have many important roles in the body that extend beyond these health markers. As long as you take the advised dosage and ensure ZMA doesn't impact any other medication, ZMA is unlikely to cause you harm. However, there is no substitute for a healthy diet when it comes to reaping the benefits of zinc, magnesium, and vitamin B6.