Introduction As first choice of nutrition, breastfeeding is widely promoted but only sufficient for the first few months oflife. Breast feeding mothers following special diets may induce certain deficiencies in their children.

Case report A 16 months old girl presents tothe Paediatric Emergency Department with extreme pallor, long-term vomiting and coughing, general weakness and drowsiness since several months. Physical examination reveals besides cachexia (weight << P3), an almost transparent pale skin, thin fine hair and a holosystolic heart murmur III/VI, also marked reduction of joy of life and obvious psychomotor development retardation. Thorough anamnesis reveals the toddler is exclusively breastfed since birth by a macrobiotic mother. Laboratory findings include extremely low hematocrit (Ht 12%)corresponding with dissociative shock; extreme erythroblastopenia in absence ofmegaloblastosis (MCV 90), low platelets (71,000/µL), very high LDH (10,000 IU/L) and triglycerides (400 mg%), elevated ferritin (440 ng/mL),but normal serum iron and TIBC. Methylmalonic aciduria following immeasurable serum vitamin B₁₂ (< 1 pg/ml) is retained as a final diagnosis. Thegirl was successfully treated by daily intramuscular vitamin B12 injections duringseveral weeks.

Conclusion In developed countries, children should not be exclusively breastfed during a prolonged period of time, especially when the motheris on a macrobiotic diet. Vitamin B12 deficiency as consequence of thisattitude, may lead to extreme erythroblastopenia and developmental retardation. This case is exceptional becauseof the unusual history as well as the very late and discrete appearance of symptoms.