Iron is a critical nutrient for triathletes and endurance athletes alike. It plays a vital role in transporting oxygen throughout the body via hemoglobin in the blood and myoglobin in the muscles. Without adequate iron, oxygen delivery to working muscles is impaired, making training and performance significantly harder.
Fortunately, understanding how to get enough iron through diet, timing, and, if needed, supplementation can make a huge difference in your energy, recovery, and race-day performance.
Why Iron Matters for Athletes
Iron is essential for:
- Oxygen transport to muscles and organs
- Energy production during endurance exercise
- Supporting recovery and overall health
For endurance athletes, oxygen is a key fuel. Therefore, low iron levels can reduce performance, increase fatigue, and slow recovery. In short, iron deficiency isn’t just a minor inconvenience, it can significantly limit your training and race outcomes.
Dietary Sources of Iron
Iron can be obtained from a variety of sources, and can be categorized as haem (animal-based) and non-haem (plant-based):
Animal-based (haem iron, highly absorbable):
- Red meat (beef, lamb)
- Chicken
- Eggs
Plant-based (non-haem iron, less easily absorbed):
- Lentils, beans, chickpeas
- Nuts and seeds
- Leafy greens and vegetables
- Iron-fortified cereals
For vegetarian and vegan athletes, it is crucial to strategically include iron-rich foods daily and enhance absorption with other nutrients.
Enhancing Iron Absorption
Several strategies can improve iron uptake:
- Pair non-haem iron with vitamin C:
- Citrus fruits, kiwifruit, strawberries, or capsicum can increase absorption.
- Avoid inhibitors during iron-rich meals:
- Calcium (from dairy or almonds) and caffeine can reduce iron absorption.
- Space consumption of these foods by about an hour from iron-rich meals.
- Timing matters:
- Iron absorption may be slightly better earlier in the day.
High-Risk Groups for Iron Deficiency
Athletes most at risk of low iron include:
- Women with regular menstrual cycles or heavy bleeding
- Vegan or vegetarian athletes with low haem iron intake
- Endurance athletes with high training loads
- Individuals with recent injuries, surgeries, or blood loss
- Pregnant or postpartum athletes
Additionally, endurance training can trigger hepcidin, a hormone that temporarily reduces iron absorption for up to 24 hours after exercise, further increasing risk for high-volume athletes.
Iron Supplementation Considerations
- Iron supplements should only be taken under medical guidance if deficiency is confirmed.
- Common forms include ferrous sulfate (Ferro-grad C) and ferric maltol (Maltofer). Gastrointestinal side effects are common, and absorption varies.
- Short-term, monitored supplementation is preferred. Long-term supplementation without deficiency is not recommended.
- Testing iron levels should consider factors like menstrual cycle, recent blood donations, and training intensity for accurate results.
Practical Tips for Athletes
- Include iron-rich foods daily – mix haem and non-haem sources if possible.
- Pair plant-based iron with vitamin C-rich foods to boost absorption.
- Separate iron-rich meals from calcium or caffeine by about an hour.
- Prioritize iron intake on rest or lighter training days.
- Monitor iron status with a GP or sports physician experienced in athletic guidelines.
- Consider using a cast iron pan for cooking!
Key Takeaways
Iron is a non-negotiable nutrient for endurance athletes. It ensures oxygen reaches your muscles, fuels your performance, and supports recovery. Without enough iron, even your best training efforts can be compromised.
If you’re struggling with low energy, frequent fatigue, or gut issues while training, it might be your iron levels holding you back. The good news is that with the right strategy from diet to timing, and supplementation if needed you can optimise your iron and get your performance back on track.