Sports Nutrition
Iron deficiency in athletes: signs and fixes
Iron deficiency is the most common nutrient deficiency worldwide, and athletes — especially female endurance athletes — sit squarely in the highest-risk group.
Why iron matters for performance
Iron is the core of hemoglobin, the protein that carries oxygen in your blood, and of myoglobin, which stores oxygen in muscle. Low iron means less oxygen delivered per heartbeat, which shows up directly as fatigue, breathlessness, and a drop in endurance capacity long before it becomes clinical anemia.[1]
How much you need
| Group | RDA |
|---|---|
| Men 19+ | 8 mg/day |
| Women 19–50 | 18 mg/day |
| Women 51+ | 8 mg/day |
| Pregnancy | 27 mg/day |
Menstruation is the main reason the requirement for women aged 19–50 is more than double that of men.[1]
Heme vs. non-heme iron
Iron comes in two forms, and they are not absorbed equally:
- Heme iron — found in meat, poultry, and fish. Absorbed far more efficiently and less affected by other things in the meal.
- Non-heme iron — found in plants, eggs, and fortified foods. Absorbed less efficiently, and inhibited by tea, coffee, and phytates in whole grains and legumes.
Vitamin C markedly improves non-heme absorption, which is why pairing plant iron sources with citrus, peppers, or tomatoes is a useful habit — and why vegan and vegetarian athletes need to plan iron more deliberately.[1]
Don't self-supplement blindly
Iron is one of the few nutrients where excess is genuinely harmful, and the symptoms of low iron overlap with plenty of other causes. Low iron should be confirmed with a blood test (ferritin plus a full blood count) before supplementing, not guessed at.
Keep reading: Plant-based protein sources · Endurance vs. strength macros · Protein intake for women