Vitamin B₁₂

Vitamin B₁₂ is a normal component of human milk.[1] The recommended daily intake in lactating women is 2.8 mcg and for infants aged 6 months or less is 0.4 mcg.[2] Some authorities recommend 5.5 mcg per day during lactation.[3] Supplementation may be necessary to achieve these recommended daily intakes or to correct a known deficiency. Low doses (1 to 10 mcg) of vitamin B₁₂ found in B complex or prenatal vitamins increase milk levels only slightly. Higher daily doses of 50 to 250 mcg are needed in cases of maternal deficiency. The breastfed infant is not exposed to excessive vitamin B₁₂ in such cases, and their vitamin B₁₂ status should improve if it was previously inadequate.

Poor health outcomes in infants with vitamin B₁₂ deficiency include anemia, abnormal skin and hair development, convulsions, weak muscle tone, failure to thrive, mental developmental delay, and possibly abnormal movements.[4-7] One well-recognized at risk group are exclusively breastfed infants of mothers with B₁₂ deficiency due to minimal or no dietary intake of animal products[8-19] or pernicious anemia caused by a maternal malabsorption of B₁₂.[17,20] Infant vitamin B₁₂ status can be improved through maternal B₁₂ supplementation during pregnancy and lactation.[21-24] Deficient mothers who miss the opportunity to supplement during pregnancy should still be encouraged to supplement during early lactation since infant vitamin B₁₂ status correlates with milk vitamin B₁₂ levels in breastfed infants up to 6 months of age.[25-28] Although there are cases reported of exclusively breastfed infants with vitamin B₁₂ deficiency having biochemical and clinical improvement through adequate maternal supplementation alone,[8] direct supplementation of the infant is recommended when such treatments are available.[29-31]