ZMA is a natural mineral supplement made up of zinc, magnesium aspartate, and vitamin B6. Zinc supports your immune system and muscles. Magnesium plays a role in metabolism, supports muscle health, and promotes restful sleep. B6 may boost energy and support brain health.
“Zinc, magnesium, and vitamin B6 are all essential micronutrients. We need them in our diets,” says Stella Volpe, PhD, RDN, head of the Department of Human Nutrition, Foods, and Exercise at Virginia Tech. “But even though minerals and vitamins are so important, taking more of them doesn't necessarily mean they're going to help us.”
What Does ZMA Do?
ZMA makers claim that increasing these three nutrients — zinc, magnesium aspartate, and vitamin B6 — in your system can build muscle strength and stamina, speed up muscle recovery, and improve the quality of your sleep.
But there’s not a lot of research to back that up.
In 2000, researchers gave ZMA supplements to a group of NCAA football players working out twice a day. After seven weeks, they found a major increase in the players’ testosterone and growth hormone, both of which are linked to muscle growth. However, one of the scientists who conducted the study holds the registered trademark for the original formula of ZMA, and their company funded the research.
Other scientists have tried to repeat the study but haven’t found the same benefits. In fact, there’s no other research suggesting that ZMA aids athletic performance or weight loss.
While there is more research suggesting that magnesium supplements might improve sleep, the studies so far have been small. There isn’t enough solid evidence to say for sure whether they really work.
So, the International Society of Sports Nutrition says that ZMA’s effect on building muscle is “not known.” The Australian Institute of Sport, which informs athletes about supplements, has also decided that ZMA lacks clear proof of benefits. There are no similar supplement-rating organizations in the U.S.
What Are the Other Benefits of ZMA?
Beyond muscle support and sleep aid, some people take ZMA for other potential health benefits — though, not all of them are backed up by good evidence. They include:
ZMA may help improve immunity. Many ZMA makers claim their supplements can support your immune system because they contain zinc, a mineral your body needs to grow and maintain cells that help fight off viruses and bacteria. But you only need a small amount of zinc each day — about 11 milligrams for adult men and 8 milligrams for adult women — which you can get naturally from foods such as meat, seafood, and legumes. Taking too much zinc can cause problems, such as making it harder for your body to absorb other important minerals like iron and copper. That’s why you should always talk to your doctor before adding a supplement that contains zinc to your routine.
ZMA's impact on sperm quality. The claim that ZMA can improve your sperm count comes from the flawed 2000 study of NCAA football players, which recorded about a 30% increase in free testosterone levels among participants taking ZMA. Because zinc plays a role in hormone production, some supplements that contain zinc — including ZMA — are marketed as a treatment for male infertility. But several newer studies show that ZMA doesn’t improve sperm count or function in healthy men.
ZMA may help regulate blood sugar. Another benefit that some ZMA makers advertise is better blood sugar control. Some studies suggest that zinc supplements can help lower fasting blood sugar in people with diabetes. There’s also research showing that magnesium might have similar effects — both in people with diabetes and those who have a high chance of developing it. But more research is needed to know for sure how effective these supplements really are.
ZMA may improve mood. Some ZMA brands claim to boost mood and support brain function as an added benefit. A recent review of studies found that magnesium supplements may help ease symptoms of depression. Other research suggests magnesium could also ease anxiety by helping regulate the stress hormone cortisol, and by keeping neurotransmitters — the on and off switches in our brains — from being overwhelmed. Still, more research is needed to fully understand how magnesium may support mental health.
Who Should Take ZMA Supplements?
ZMA supplements are often marketed to athletes to improve muscle strength and recovery. But research suggests they don’t actually improve training results. If you have a deficiency in zinc, magnesium, or B6, you may benefit from taking ZMA, but Volpe suggests changing your diet first, since most people can get enough of these nutrients by eating the right foods.
“My cautionary approach is always — if the bucket is full, why try to overfill it?” she says. “We want to make sure that we don't overdo it because people can get negative effects from overtaking any vitamin or mineral supplement.” Always talk to your doctor before starting any new supplement, especially because some can interact with medications.
What is the recommended dosage for ZMA?
The recommended dose of ZMA might vary slightly by brand, but most suggest three capsules per day for men and two capsules per day for women. If you’re not deficient in these nutrients, Volpe advises taking less than the recommended amount. “You're still getting zinc, magnesium, and B6 from food,” she says. “If you take too much, you won’t absorb all of it, so why take the chance to overdo it?”
A typical serving provides:
- 30 milligrams of zinc for men/20 milligrams for women
- 450 milligrams of magnesium for men/300 milligrams for women
- 10-15 milligrams vitamin B6 for men/7-10 milligrams for women
Most brands recommend taking ZMA on an empty stomach about an hour before bed.
Supplements in the U.S. aren’t regulated in the same way that medications are, so Volpe suggests choosing a brand that’s been third-party tested. “It ensures that what it says is in there is really in there,” she says. She also advises checking the label for the elemental amount of each mineral listed on the bottle — it tells you how much of the nutrient you’re really getting.
ZMA Side Effects
No major side effects of ZMA have been reported, but there could be health concerns if the supplements are taken more frequently than the drugmaker suggests.
Too much zinc or magnesium can cause diarrhea, nausea, and cramping. When taken in high doses over a period, zinc can lower the body’s immunity and its levels of HDL, or “good,” cholesterol. One study also found that men who took 100 milligrams of zinc supplements for 10 years were more likely to get prostate cancer, but the reason isn't clear. Taking too much supplemental B6 for a year or more may cause nerve damage.
More immediate concerns: Zinc and magnesium can make it harder for your body to absorb some prescription medications, such as antibiotics, while B6 supplements can intensify the side effects of certain drugs.
What Are the Natural Food Sources of Zinc and Magnesium?
You can lose zinc and magnesium when you sweat a lot or urinate, but the loss is usually temporary. Some people have low magnesium levels because of certain medications they take (like proton pump inhibitors) or because of alcohol use.
A simple way to replenish these minerals is through the food you eat. Foods that are a good source of magnesium include:
- Spinach
- Nuts and seeds, especially pumpkin seeds, almonds, and cashews
- Whole grains
- Beans
- Low-fat dairy products
- Dark leafy greens
- Avocados
The following foods are high in zinc:
- Oysters
- Red meat
- Poultry
- Breakfast cereals
- Lentils
If you’re looking to add more vitamin B6 to your diet, try to eat more:
- Fish
- Beef liver
- Potatoes and other starchy vegetables
- Chickpeas
- Bananas
Before taking any supplements, make sure to talk to your doctor, a registered dietitian, or pharmacist to see if it’s right for you.
Takeaways
ZMA is a supplement made of zinc, magnesium aspartate, and vitamin B6 that’s often marketed to athletes for muscle recovery, improved performance, and better sleep. While these nutrients are important for overall health, most research doesn’t back up the claimed benefits of ZMA — especially when it comes to athletic performance. Most people can get enough zinc, magnesium, or B6 through the foods they eat, but if you think you might be deficient, talk to your doctor or a dietitian before starting a supplement.
ZMA FAQs
Is it safe to take ZMA every day?
ZMA is generally safe when taken as recommended, but too much zinc or magnesium can cause side effects.
Can ZMA cause weight gain?
There’s no evidence that ZMA causes weight gain.
What does ZMA supplement do?
ZMA is often marketed to improve muscle recovery, athletic performance, and sleep. Some people also take it to support immunity, mood, and blood sugar levels. But there’s limited research to back up these health claims.
How long does it take for ZMA to work?
Most supplements take between four and six weeks to have an effect, but they don’t work the same way for everyone.