A 9-month-old exclusively breastfed infant presents with pallor, irritability, and hypotonia. Hb is 7.2 g/dL, MCV 59 fL, serum ferritin 4 ng/mL. Mother's dietary history shows no red meat, poultry, or iron-rich foods. Which mechanism BEST explains why exclusive breastfeeding beyond 6 months without complementary feeding leads to iron deficiency?
- A Breast milk contains no iron whatsoever
- B Breast milk contains phytates that inhibit iron absorption
- C Breast milk iron content (0.3–0.5 mg/L) is insufficient to meet needs beyond 6 months as fetal iron stores are depleted by then ✓
- D Exclusive breastfeeding causes malabsorption of all minerals
Explanation
Breast milk is a poor source of iron in absolute quantity (~0.3–0.5 mg/L); however, its iron is highly bioavailable (~50% absorbed). During the first 4–6 months, the term infant's fetal iron stores (laid down in the third trimester) supplement the iron from breast milk and meet the daily requirement. By 6 months, fetal stores are largely exhausted and breast milk iron alone (~0.27 mg/day) is insufficient to meet the growing infant's requirement (~11 mg/day RDA at 7–12 months). This explains why exclusive breastfeeding beyond 6 months without iron-rich complementary foods predictably leads to iron deficiency anemia. Phytates are present in plant foods, not breast milk.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.