Magnesium

Does it work?

• -Only if you're low. Magnesium won't make you stronger or recover faster if your levels are already normal — trials in healthy, active people show no real benefit. But a lot of people run short, and if you do, correcting it can modestly help sleep onset and ease that twitchy, restless feeling. Treat it as fixing a gap, not a performance booster.

How much · when

• -200-400 mg of elemental magnesium per day. The label number is often the compound weight, not elemental — check the elemental amount.
• -Take it in the evening with food. Most of the upside is sleep and relaxation, and food cuts the chance of loose stools.
• -Choose glycinate or citrate. They absorb well and are gentle. Skip oxide — it's cheap but poorly absorbed and the most likely to cause diarrhea.
• -Diet first: leafy greens, nuts, seeds, beans, and whole grains. If you already eat these, you may not need a pill at all.

The catch

• -Healthy, well-fed athletes show no gain in strength, power, or recovery from extra magnesium — the muscle-fitness benefits in the research come almost entirely from deficient groups (the elderly, heavy drinkers).
• -The sleep effect is real but small — roughly 17 fewer minutes to fall asleep in the best meta-analysis, and the underlying trials were modest quality.

Safety

• -High doses from supplements (above ~350 mg/day of supplemental magnesium) commonly cause diarrhea and cramping — oxide is the worst offender.
• -If you have kidney disease, talk to a doctor first; impaired kidneys can let magnesium build to dangerous levels.
• -Magnesium can interfere with absorption of some antibiotics and thyroid medication — separate doses by a few hours.

Key research

• Can Magnesium Enhance Exercise Performance?Nutrients · 2017 · Review
• The effect of magnesium supplementation on muscle fitness: a meta-analysis and systematic reviewMagnesium Research · 2017 · Meta-analysis
• Magnesium for skeletal muscle crampsCochrane Database of Systematic Reviews · 2020 · Systematic review
• Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-AnalysisBMC Complement Med Ther · 2021 · Meta-analysis

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