The Tired Swimmer: Iron Deficiency in a 14-Year-Old

Low iron status has three contributors: reduced intake, reduced absorption and increased loss.

• Intake: Sofia's day contains very little haem iron (she is pescatarian and dislikes oily fish) and modest non-haem iron. Cheese, white bread, crisps and cola are low in iron; pasta with tomato sauce contributes some, but the total is unlikely to meet the 14.8 mg/day reference nutrient intake for a 14-year-old girl.
• Absorption: non-haem iron needs vitamin C in the same meal to be reduced to Fe2+ and absorbed. Her lunch has no fruit or vegetables rich in vitamin C, and the cheese provides calcium, which competes with iron. Tea contains tannins/polyphenols that bind iron; at 21:00 it is two hours after dinner, so its effect is smaller than if drunk with the meal, but if she has biscuits and tea as a snack it still reduces absorption from that snack.
• Losses: six-day heavy periods are a major cause of iron deficiency in adolescent girls; each millilitre of blood contains about 0.5 mg iron, so heavy loss can exceed dietary absorption.
• Pattern: skipping breakfast means a long fast and low energy; tiredness and stopping swimming suggest low energy availability.

The ferritin of 8 µg/L shows depleted stores, so diet alone will be slow. The answer is not 'which single cause' but the combination: low intake + poor absorption + high menstrual loss.

Plan (approximate, budget-conscious):

• Breakfast: 40 g fortified wholegrain cereal + 150 ml orange juice; or porridge made with water + sultanas.
• Mid-morning: banana + small handful of peanuts (or pumpkin seeds).
• Lunch: 300 ml lentil and tomato soup + 2 slices wholemeal bread + an orange.
• Afternoon: hummus with red pepper strips.
• Dinner: bean and spinach curry with 150 g rice, lemon juice squeezed over; 1 small wholemeal pita.
• Supper: 200 ml milk or yogurt (keep dairy away from the iron-rich meals).

Justification:

1. Vitamin C pairing: orange juice at breakfast and orange at lunch increase absorption of non-haem iron; 50 mg vitamin C can roughly triple absorption from a meal.
2. Plant iron sources: lentils, beans, spinach and fortified cereal are cheap per mg iron; adding lemon at dinner gives acid and vitamin C.
3. Avoid inhibitors at main meals: tea/coffee should be at least one hour away; cheese and milk are moved to supper so calcium does not compete at dinner.
4. Energy and fibre: regular meals address tiredness and support concentration; wholemeal bread adds fibre and B vitamins. Cost is kept low by using pulses, oats, seasonal fruit and supermarket own-brand cereal; this is a realistic €4–6/day in Malta. The plan does not 'cure' deficiency alone but supports the prescribed iron and improves absorption.

Side effects: constipation and abdominal discomfort/nausea are common with ferrous sulphate; dark/black stools are harmless but alarming if not explained.

Strategies: (1) take with a source of vitamin C (e.g. a small glass of orange juice) and on an empty stomach if tolerated; (2) avoid tea, coffee, calcium supplements and antacids within about an hour of the dose; (3) if GI upset is severe, ask the GP about alternate-day dosing or a different salt, but do not stop the prescription.

Why food alone may not be enough: a typical diet provides about 10–15 mg iron, of which only 1–2 mg is absorbed; a 200 mg ferrous sulphate tablet provides 65 mg elemental iron, of which perhaps 10–20 mg is absorbed when stores are low. Heavy menstrual loss can exceed what diet can replace, and rebuilding ferritin takes three to six months after haemoglobin normalises. Food is essential for long-term maintenance, but it is unrealistic to expect it to correct a ferritin of 8 µg/L quickly.