ZMA is a popular dietary supplement for athletes and active individuals. Its main ingredients — zinc, magnesium and vitamin B6 — support overall health. This formula is marketed as a natural energy booster, recovery aid and even fat burner. While most claims lack scientific evidence, ZMA may help prevent nutrient deficiencies. Before you start using it, take time to research ZMA side effects and potential benefits.
What Is ZMA?
This supplement contains zinc and magnesium aspartate plus vitamin B6. ZMA dosage varies among brands. The formula from Optimum Nutrition, for example, provides 200 percent of the recommended dietary allowance (RDA) of zinc, 525 percent of the RDA of vitamin B6 and 113 percent of the RDA of magnesium per serving. The ZMA supplement from My Protein, by comparison, delivers 200 percent of the RDA of zinc, 500 percent of the RDA of vitamin B6 and 80 percent of the RDA of magnesium.
According to manufacturers, these three micronutrients support muscle growth and repair, speed recovery and boost immune function. Some say that it also helps maintain healthy testosterone levels, wards off fatigue and improves muscle function. Unfortunately, there isn't enough scientific proof to confirm these benefits.
Zinc and Magnesium Benefits
As a 2015 study published in the journal Evidence-Based Practice shows, ZMA supplementation doesn't increase testosterone levels in previously active men. Its ingredients, however, have other potential health benefits. Zinc supports DNA and protein synthesis, accelerates wound healing and enhances your body's natural defenses.
Read more: Magnesium, Testosterone & Zinc
Magnesium, another key ingredient in ZMA, contributes to more than 300 enzymatic reactions in the human body. According to a 2013 review published in the journal Nutrients, optimal magnesium intake supports bone health and protects against osteoporosis. This nutrient has also been shown to lower the risk of coronary artery calcification, improve exercise performance and reduce inflammation.
The Role of Vitamin B6
In addition to zinc and magnesium, this formula contains vitamin B6. Also known as pyridoxine, it plays a key role in protein, carbohydrate and lipid metabolism. Vitamin B6 also keeps your immune system strong and aids in the production of red blood cells.
But how safe are ZMA supplements? Are there side effects you should be aware of?
Digestive Discomfort and Gastrointestinal Symptoms
Both zinc and magnesium may cause nausea, vomiting and digestive discomfort when consumed in excess. According to WebMD, routine zinc supplementation might lead to kidney and stomach damage in addition to the previously mentioned side effects.
Read more: Nausea After Zinc
It's important to note that these reactions are unlikely to occur if you stick to the daily recommended dosage of ZMA. They're more common in those who take large doses of either magnesium or zinc. If you experience any adverse effects, consult a medical professional.
Zinc and Prostate Cancer
According to a 2017 article that appeared in the Natural Medicine Journal, taking more than 100 mg of zinc daily may double the risk of prostate cancer in men. A 2014 study published in the journal Metallomics indicates that zinc may cause prostate cancer cells to become resistant to cisplatin and other chemotherapy drugs, reducing the chances of recovery. Other studies show the opposite, that zinc may actually lower the risk of dying from prostate cancer.
As the Natural Medicine Journal notes, these findings are conflicting. What's interesting, though, is that dietary zinc appears to protect against cancer, while supplemental zinc may increase cancer risk. Most studies involved large doses of zinc, which is not the case when you're taking ZMA.
The Bottom Line
Most ZMA brands contain small or moderate doses of zinc, magnesium and vitamin B6, so you're unlikely to experience side effects. However, be aware that even a quality ZMA supplement can interfere with certain medications and may not be safe for those with existing health conditions.
Zinc, for example, which is one of its main ingredients, may interact with antibiotics and diuretics. Magnesium can decrease the absorption of digoxin, bisphosphonates, gabapentin and certain medications for diabetes and high blood pressure. Furthermore, it may cause bleeding when used in combination with anticoagulants. Vitamin B6 interacts with 35 drugs, including aspirin, ibuprofen, Prozac and several dietary supplements.
ZMA side effects are uncommon in healthy individuals. To stay on the safe side, talk to a doctor before you start taking this supplement. Read ZMA reviews online and check the labels so you can make an informed decision.
- Endocrine Abstracts: Effects of Zinc, Magnesium and Vitamin B6 (ZMA) Supplementation on Serum IGF-I, IGFBP-3 and Testosterone Concentrations in Young Athletes
- Optimum Nutrition: ZMA
- My Protein: ZMA
- Evidence-Based Practice: Does Supplementation With Zinc Magnesium Aspartate (ZMA) Increase Levels of Serum Testosterone in Men?
- NIH: Zinc
- NIH: Magnesium
- Nutrients: Magnesium and Osteoporosis — Current State of Knowledge and Future Research Directions
- JACC Cardiovascular Imaging: Magnesium Intake Is Inversely Associated With Coronary Artery Calcification
- PLOS ONE: Magnesium Enhances Exercise Performance via Increasing Glucose Availability in the Blood, Muscle and Brain During Exercise
- Archives of Medical Research: Oral Magnesium Supplementation Decreases C-Reactive Protein Levels in Subjects With Prediabetes and Hypomagnesemia
- NIH: Vitamin B6
- NIH: Magnesium: Health Risks From Excessive Magnesium
- WebMD: Zinc
- Natural Medicine Journal: Zinc for Prostate Cancer May Not Be a Good Idea
- Metallomics: KRAS NF-κB Is Involved in the Development of Zinc Resistance and Reduced Curability in Prostate Cancer
- Linus Pauling Institute: Vitamin B6 Toxicity
- RX List: Zinc
- RX List: Magnesium
- Drugs.com: Vitamin B6 (Pyridoxine) Drug Interactions