Zinc and magnesium are two of the most important minerals in the human body — and two of the most commonly depleted in athletes. They regulate hundreds of biochemical reactions between them, from protein synthesis and muscle function to testosterone production, immune response and sleep quality.
The frustrating part is that most people — even those eating reasonably well — are running low on both. Studies show the majority of people on self-selected diets are getting less than two thirds of the recommended daily intake for zinc.
Magnesium deficiency is even more widespread. And those studies were conducted on non-active people. Athletes and people who train regularly deplete their mineral stores significantly faster than everyone else — several studies have shown zinc and magnesium stores can be depleted within days after strenuous activity.
In other words: if you’re training hard and not paying attention to these two minerals, you’re almost certainly leaving gains on the table. Here are some early warning signs your body’s magnesium levels are dangerously low.
What Does Zinc Actually Do?
Zinc is found in every cell throughout the body and is involved in more than 100 enzymatic reactions. Its most relevant functions for athletes:
Testosterone and anabolic hormone support. Zinc directly optimizes testosterone and insulin in healthy men. A deficiency means your body’s ability to produce and utilize anabolic hormones is compromised — which translates directly to slower muscle growth and weaker recovery regardless of how hard you train.
Muscle repair and growth. Zinc promotes tissue repair, supports muscle healing and boosts immune function — all critical components of recovery from hard training.
Lactic acid management. The enzymes responsible for inhibiting the buildup of lactic acid — the fatigue acid that makes your muscles burn during intense sets — require zinc to function properly. Low zinc means faster fatigue and reduced endurance.
Immune function. Zinc supplements have been shown to lower the risk of infections, boost immune response and aid in fighting colds and flu. For athletes who train hard year-round, maintaining immune function isn’t optional.
Wound healing and cell growth. Zinc plays a key role in cell division, DNA synthesis and normal growth — making it essential not just for muscle building but for overall physical health.
Best Food Sources of Zinc
Red meat, liver, oysters, dairy, whole grains, beans, nuts and chicken. Oysters are the richest source by far.
Related: Seven of the best Zinc Rich Foods
Common Causes of Zinc Deficiency
Alcohol consumption is the most common cause — alcoholic beverages deplete zinc rapidly, and most heavy drinkers also eat poorly to begin with. Other causes include a diet high in processed foods, certain medications and intestinal conditions that impair absorption.
Daily Requirement
Adults need 8–12mg of zinc per day. Athletes should aim for the higher end of this range.
What Does Magnesium Actually Do?
Magnesium is essential to muscle and brain function, cardiovascular health, memory, digestion and immunity. For athletes specifically:
Oxygen delivery to muscle tissue. A magnesium deficiency directly decreases the delivery of oxygen to muscle tissue — which means reduced endurance, impaired strength and slower recovery.
Amino acid and carbohydrate metabolism. Magnesium stimulates enzyme activity required for the body to metabolize both amino acids and carbohydrates. Without adequate magnesium, your body can’t efficiently use the protein and carbs you eat to fuel training and build muscle.
Sleep and recovery. Magnesium activates the parasympathetic nervous system, helping the body wind down and relax before sleep. It also plays a role in melatonin regulation — the hormone responsible for normal sleep cycles. Better sleep means better recovery, higher growth hormone output and more testosterone.
Anti-inflammatory effects. Magnesium lowers systemic inflammation by inhibiting calcium-induced inflammation pathways in cells. Low magnesium levels cause inflammatory cytokines — specifically interleukin-6 and TNF-alpha — to elevate in the body. Both of these molecules are linked to heart attacks and congestive heart failure, and both are signs of active inflammation. Increasing magnesium intake reduces levels of both proteins.
Magnesium and testosterone. This connection is backed by solid research. Scientists at the University Hospital of Parma studied nearly 400 men aged 65 and older and found that every man with higher magnesium levels also had higher testosterone and IGF-1 levels. In a separate study conducted by Turkish and Italian scientists, giving athletes 1g of magnesium sulphate per day significantly increased their testosterone levels.
The suspected mechanism: inflammatory processes and free radical damage decrease testosterone production, and inflammation worsens as magnesium levels drop. Cells with adequate magnesium release fewer inflammatory factors because antioxidant enzymes require magnesium to function. Less magnesium means more inflammation, which means less testosterone.
Mood and mental health. Low magnesium levels appear to reduce serotonin production. A 2008 study found magnesium was as effective as antidepressants in treating depression in people with diabetes — a finding that rarely gets discussed in athletic contexts but matters for anyone dealing with chronic training stress.
Aging. Studies show that magnesium deficiency accelerates the aging process. Combined with the testosterone and IGF-1 connection, this makes adequate magnesium intake one of the most important long-term health decisions an athlete can make.
Relaxation and cramp prevention. One of the most practically noticed benefits of magnesium supplementation is the reduction in muscle cramps and spasms — directly relevant to anyone doing high-volume training.
Important Note on Blood Tests
Around 99% of the body’s magnesium is located inside cells, not in the bloodstream. This means standard blood tests are not a reliable way to detect magnesium deficiency — you can have perfectly normal blood levels and still be significantly deficient at the cellular level. The only reliable approach is to ensure you’re consistently eating foods high in magnesium and supplementing if your diet is falling short.
Best Food Sources of Magnesium
Spinach, kale, broccoli, avocado, potatoes, bananas, legumes, whole grains, pumpkin seeds, sunflower seeds, almonds, cashews, Brazil nuts, tuna, dark chocolate, kiwi, mango and orange. Leafy greens and nuts are consistently the richest sources.
Common Causes of Magnesium Deficiency
Intestinal conditions (IBS, Crohn’s), kidney disease, high thyroid levels, diabetes, alcohol addiction, chronic stress, certain medications and a diet high in processed foods. Calcium supplements and soft water can also impair magnesium absorption. The biggest driver across the general population is simply the shift away from fruits and vegetables toward processed foods — the main dietary sources of magnesium are being systematically removed from most people’s diets.
Therapeutic Uses
Magnesium is used clinically for severe asthma, migraines, arrhythmia, leg cramps, constipation, insomnia, premenstrual syndrome and blood pressure management. It also improves insulin sensitivity. For athletes, the sleep, recovery and testosterone benefits are the most immediately relevant.
Daily Requirement
Adults need 310–400mg of magnesium per day. Most people don’t come close to this through diet alone.
What Is ZMA and Does It Work?
ZMA is a supplement combining zinc, magnesium and vitamin B6 in specific ratios. It became popular in athletic circles after research showed meaningful benefits for testosterone, recovery and sleep quality in men who were deficient in these minerals.
On testosterone: ZMA can optimize testosterone levels — but primarily in individuals with lowered testosterone caused by zinc or magnesium deficiency. Studies confirm it won’t significantly raise testosterone in men who already have healthy levels of both minerals. If you’re training hard, sweating regularly and not supplementing, deficiency is more likely than you think.
On sleep: This is where ZMA has the most consistent evidence. Zinc enhances sleep quality, magnesium activates the parasympathetic nervous system for relaxation and both work together to support melatonin regulation. The combination produces meaningfully better sleep quality for most users — and better sleep means more growth hormone, better recovery and higher testosterone the next day.
On immunity: Zinc reduces infection risk and speeds up recovery from colds and flu. Vitamin B6 is required for the production of antibodies that fight infections. Together they give the immune system a meaningful boost — important for athletes who put their bodies under repeated stress.
The Full Benefits of Zinc and Magnesium Supplementation
When both minerals are adequate, athletes consistently report:
- Increases in muscular endurance and strength
- Reductions in muscle pulls and cramps
- Faster healing and injury recovery
- Higher alertness and concentration
- Reduced water retention
- Improved relaxation and sleep quality
- Better immune function and resistance to illness
How to Supplement: Dosage and Timing
Getting the timing right matters more with ZMA than with most supplements.
Dosage:
- Zinc: 20–30mg
- Magnesium: 450mg
- Vitamin B6 is typically included in ZMA formulas at 10–11mg
Timing: Take ZMA at least 30 minutes before bed on an empty stomach. Wait 1–2 hours after your last meal before taking it. Here’s why this matters: zinc’s effect on the body is maximized during the sleep cycle, when the body enters repair mode. The biggest surge of growth hormone occurs approximately 1.5 hours into sleep — and because testosterone, magnesium and zinc all amplify the effects of growth hormone, taking the supplement around bedtime gives you maximum absorption and maximum benefit during the most anabolically active window of your day.
Critical note: don’t take calcium at the same time. Calcium directly competes with zinc and magnesium for absorption. If you take a calcium supplement, separate it from your ZMA by several hours — or take ZMA before bed and calcium with a meal earlier in the day.
Food Sources vs Supplementation
A well-constructed diet can cover your zinc and magnesium needs — but for athletes training at high intensity, food alone often isn’t enough. Sweat depletes both minerals rapidly and the amounts lost through hard training sessions can exceed what even a good diet replaces.
If you’re eating plenty of red meat, leafy greens, nuts and whole grains and training at moderate intensity, you may be fine without supplementation. If you’re training hard four or more times per week, supplementing with ZMA is a low-cost insurance policy with meaningful upside and essentially no downside.
Zinc and magnesium supplements are also commonly recommended for pregnant women and those following low-calorie diets — two groups at elevated risk of deficiency regardless of training status.
The Bottom Line
Lacking in just one area — whether it’s micronutrients, macronutrients or sleep — your gains will suffer from it. Zinc and magnesium are two of the areas most athletes overlook, and given how rapidly training depletes both, deficiency is more common than most people realize.
Supplement with ZMA before bed, keep calcium separate, hit your daily targets and you’ll have covered one of the most commonly neglected bases in athletic nutrition. It’s not glamorous, but neither is leaving gains on the table because of an easily fixable mineral deficiency.
For more on supplements that support testosterone production, see our complete guide to natural testosterone boosters.
