What iron does
Iron is central to haemoglobin, which carries oxygen in the blood, and to the muscle's own oxygen handling. When stores fall, oxygen delivery suffers, and the first thing an athlete notices is that the same session feels harder.
Because it comes on gradually, most athletes adjust to it rather than reporting it. Parents usually notice the performance plateau before anyone notices the cause.
What it looks like
- Tiredness that does not improve with rest.
- Breathless earlier in sessions than usual.
- Heart racing during moderate work.
- Performance flat or declining despite training well.
- Pale appearance, headaches, cold hands and feet.
- Poor concentration at school.
- Frequent minor illness.
Why athletes are at higher risk
- Menstrual blood loss, especially with heavy periods.
- Higher requirements during growth and heavy training.
- Small losses through sweat, gut and repeated foot impact in runners.
- Vegetarian and vegan diets, where iron is harder to absorb.
- Eating little red meat, common in teenagers.
- Under-fuelling generally, which tends to reduce iron intake too.
Getting it tested properly
Ask the GP for a full blood count and ferritin, and mention that she is a training athlete. Ferritin reflects iron stores and can be low while the standard anaemia check still looks normal, which is why a request for both matters.
It is worth asking about vitamin D at the same appointment, since the two often turn up together in indoor-training teenagers.
What to ask for
Full blood count plus ferritin, and mention heavy periods, training hours and any vegetarian or vegan diet.
Food sources that actually shift it
- Red meat, the most easily absorbed source.
- Chicken, turkey, fish and eggs.
- Beans, lentils, tofu and chickpeas.
- Fortified breakfast cereals, check the label.
- Dark leafy greens and dried apricots.
- Pair plant sources with vitamin C, orange juice, peppers, tomatoes, to absorb more.
- Keep tea and coffee away from iron-rich meals, they reduce absorption.
Supplements, carefully
Iron supplements work, but only where there is a deficiency, and excess iron is genuinely harmful. That makes this a test-first situation rather than a try-it-and-see one.
If a GP prescribes iron, expect a course of several weeks to months with a repeat blood test, and expect to address the cause too. Correcting stores without dealing with heavy bleeding or low intake simply repeats the cycle.