Minerals for Athletes and Active People: Sweat Losses, Iron, Magnesium, Zinc and Doping Cautions
What research shows about iron, magnesium, zinc and sweat losses in athletes, why testing comes before supplements, and how contamination and doping rules affect product choice.
Content last updated . This page has not been medically reviewed.
Seek care first
- If someone collapses, is confused or has a seizure during or after hard exercise, call 911 in the US. See Hyponatremia in endurance exercise and hot weather for what low blood sodium means.
- If anyone may have swallowed iron tablets, call 911 or Poison Help at 1-800-222-1222 in the US. The NHS says very high doses of iron can be fatal, particularly in children. [1]
- Persistent tiredness, falling performance or dizziness deserve a clinician's assessment, not a guess. See Anemia and iron deficiency.
The short answer
Active people lose some minerals in sweat, and some athletes, especially women and endurance athletes, are commonly found to have low iron. [2] But a 2019 systematic review found little evidence that mineral supplements improve performance, with the possible exceptions of iron in particular situations and magnesium. [3] This page is information only and does not replace advice from a clinician or sports dietitian.Official intake levels (general adults)
The sources we read give no separate official figures for athletes (Proper evidence not found in NHS, MedlinePlus, EFSA or Health Canada tables for athlete-specific values), so these are the general adult levels. They are published reference levels, not a plan.| Mineral | Reference intake per day | Upper level per day | Source and year |
|---|---|---|---|
| Iron | US: men 8 mg; women 18 mg (19 to 50). UK: men 8.7 mg; women 14.8 mg (19 to 49) | Canada: 45 mg. UK: 17 mg or less from supplements "unlikely to cause any harm"; continue a higher amount if a GP advises | MedlinePlus 2025; NHS 2020; Health Canada 2025 |
| Magnesium | US: men 400 to 420 mg; women 310 to 320 mg. UK: men 300 mg; women 270 mg | UK: 400 mg or less from supplements unlikely to cause harm. Canada: 350 mg from supplements only | MedlinePlus 2025; NHS 2020; Health Canada 2025 |
| Zinc | US: men 11 mg; women 8 mg. UK: men 9.5 mg; women 7 mg | UK: no more than 25 mg from supplements unless advised. Canada: 40 mg | MedlinePlus 2025; NHS 2020; Health Canada 2025 |
[4] [5] [6] [1] [7] [8]
How label amounts relate to these figures (elemental versus compound weight) is on Understanding minerals.
What the research found
Evidence labels: established is a documented role or deficiency treatment; limited, mixed and insufficient describe how consistent or small the evidence is.| Question | What the source found | Strength |
|---|---|---|
| How common is low iron in athletes? | A narrative review reported iron deficiency in roughly 15 to 35% of female athlete groups and 5 to 11% of male groups, and noted exercise raises hepcidin, a hormone that regulates iron. [2] | Observational |
| Do iron pills help athletes? | A meta-analysis of 13 studies (449 athletes) found ferritin rose, mainly when starting ferritin was 12 µg/L or lower; hemoglobin did not change significantly and the VO2max change was a non-significant trend. [9] | Limited; helps stores when low |
| Do minerals improve performance in general? | 130 experiments found little evidence for mineral supplements, except possibly iron and magnesium, and many minerals had no good-quality studies. [3] | Limited |
| Does magnesium prevent cramps? | A Cochrane review of 11 trials (pregnancy and idiopathic cramps, largely older adults) found no significant difference from placebo in idiopathic cramps. [10] Proper evidence not found for exercise-induced cramps in the reviews we read. | No good evidence of benefit (idiopathic) |
| Can sweat sodium be predicted? | Sweat sodium varies considerably within and between people; a large analysis explained only 17 to 23% of the variation, and sweat testing methods can give inconsistent results. [11] [12] | Limited |
Doping and product quality
A clinical review found poor manufacturing and intentional contamination with banned substances still occur in supplements sold in the US, mainly in weight-loss and muscle-building products, and suggested third-party certified products to reduce risk. [13] Competitive athletes should read Sports certification and banned-substance contamination and Quality testing and certifications, and check with their governing body.Frequently asked questions
Do athletes need more iron?
Low iron is commonly found in female and endurance athletes. [2] Whether you need iron depends on a blood test and a clinician's advice. [9]
Do mineral supplements improve performance?
A systematic review found little evidence, with possible exceptions for iron in particular situations and magnesium. [3]
Does magnesium prevent muscle cramps?
Not in the trials Cochrane reviewed for idiopathic cramps. [10]
Do I lose a lot of minerals in sweat?
It varies a lot between people and conditions. [11] Ask a sports dietitian about testing rather than copying another athlete.
Are mineral supplements safe for drug-tested athletes?
Contamination in some supplements is documented, so look for third-party certification and check your sport's rules. [13]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Practical limits of the research
- Test before supplementing. Ferritin and related tests have limits; see Deficiency testing and its limits and Iron for athletes, heavy periods and blood donors.
- Unneeded iron can harm people with iron overload; see Iron overload and hemochromatosis.
- Electrolyte drinks and powders are covered in Electrolyte powders, drinks and tablets.
Safety and who should ask first
Medicines: the NHS lists calcium and iron supplements among products that may not mix well with levothyroxine. [14] Teen athletes should see Vitamins for children and teens. Kidney or liver conditions, pregnancy and upcoming surgery all change what is safe; tell your clinician or pharmacist about every product (Medication interactions).
References
- NHS (UK). Vitamins and minerals: Iron. Page last reviewed 3 August 2020. Read 2026-10-23.
- Sim M et al. Iron considerations for the athlete: a narrative review. Eur J Appl Physiol 2019;119:1463-1478. PubMed abstract (PMID 31055680). Read 2026-10-23.
- The role of mineral and trace element supplementation in exercise and athletic performance: a systematic review. Nutrients 2019;11:696. PubMed abstract (PMID 30909645). Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Iron in diet. Review date 1/21/2025. Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Magnesium in diet. Review date 1/21/2025. Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Zinc in diet. Review date 1/21/2025. Read 2026-10-23.
- NHS (UK). Vitamins and minerals: Others (magnesium, potassium, selenium, zinc and others). Page last reviewed 3 August 2020. Read 2026-10-23.
- Health Canada, Dietary reference intakes tables: Reference values for elements, page dated 2025-11-19. Read through the WebFetch tool, whose output is a model-made extract of the table, so these figures should be treated as (WebFetch extract). Read 2026-10-23.
- Effects of oral iron supplementation on blood iron status in athletes: a systematic review, meta-analysis and meta-regression of randomized controlled trials. Sports Med 2024;54:1231-1247. PubMed abstract (PMID 38407751). Read 2026-10-23.
- Garrison SR et al. Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev 2020;9:CD009402. PubMed abstract (PMID 32956536). Read 2026-10-23.
- Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability. Sports Med 2017;47(suppl 1):111-128. PubMed abstract (PMID 28332116). Read 2026-10-23.
- Explaining variation in sweat sodium concentration: effect of individual characteristics and exercise, environmental, and dietary factors. J Appl Physiol 2022;133:1250-1259. PubMed abstract (PMID 36227164). Read 2026-10-23.
- Prohibited contaminants in dietary supplements. Sports Health 2018;10:19-30. PubMed abstract (PMID 28850291). Read 2026-10-23.
- NHS (UK). Levothyroxine (medicine page). Page last reviewed 6 July 2026. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.