Is Vitamin B 12 safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Vitamin B 12. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
Twelve exclusively breastfed infants between 4 and 11 months of age had biochemical, hematological and clinical findings consistent with vitamin B 12 deficiency. Their mothers received a 50 mcg single dose of intramuscular vitamin B 12 . Within 5 to 8 days after the dose, the infants experienced significantly increased hemoglobin and reticulocyte counts, normoblastic erythropoiesis, improved mental status, regression of abnormal skin pigmentation, and reduction in tremors.[ 9 ] Three hundred sixty-six pregnant women in India received 50 mcg of oral vitamin B 12 or placebo capsules once daily beginning during their first trimester of pregnancy and continuing until 6 weeks postpartum. Among 218 infants that underwent neurodevelopment testing at 30 months of age, those born to mothers randomized to vitamin B 12 had higher expressive language scores than the placebo group when adjusted for baseline maternal vitamin B 12 deficiency. Cognitive, receptive language and motor scores were not different between the two groups.[ 26 ] Neurophysiological assessments were then conducted at 6 years of age and there were no differences in the measured brain activity between the two groups.[ 52 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Methylcobalamin is the major form of vitamin B 12 in milk. Deoxyadenosylcobalamin, hydroxocobalamin and cyanocobalamin are minor forms.[ 1 ] When measured in milk, all forms or "total" vitamin B 12 levels are reported. Breastmilk vitamin B 12 levels are correlated with maternal intake and maternal blood levels.[ 34 , 35 ] Infant vitamin B 12 levels are correlated with maternal blood and milk levels.[ 36 ] Infant vitamin B 12 blood levels are significantly lower, and the rate of vitamin B 12 deficiency is significantly higher, in exclusively breastfed infants compared to those who are exclusively formula fed.[ 37 ] A vitamin B 12 blood level 150 pmol/L ( 203 ng/L) is considered a biochemical indicator of deficiency.[ 38 ] A blood level 220 pmol/L ( 298 ng/L) indicates adequate vitamin B 12 status, and values between 150 and 220 pmol/L are considered marginally adequate.[ 23 , 39 ] These are traditional epidemiological cutoffs and not necessarily diagnostic. Numerous laboratory tests in addition to vitamin B 12 blood levels and clinical examination are used to diagnose vitamin B 12 deficiency.[ 40 , 41 ] Maternal Levels. Average milk levels in mature milk are 200 to 700 pmol/L (270 to 950 ng/L) during the first 28 weeks postpartum in healthy, lactating women with known or presumed adequate vitamin B 12 status and not taking a supplement.[ 27 , 28 , 42 - 45 ] Levels are highest during the first 4 weeks postpartum and gradually decrease thereafter.[ 25 , 28 , 29 , 42 - 47 ] Hindmilk levels are 20% to 30% higher than foremilk.[ 29 ] In populations with a high prevalence of vitamin B 12 deficiency or insufficient dietary vitamin B 12 intake, reported median or average milk levels are 120 to 160 pmol/L (160 to 220 ng/L) at 6 months postpartum.[ 30 , 46 ] In one study of 210 lactating women from different regions of Cameroon, rates of maternal vitamin B 12 deficiency were 15% to 25% and median milk levels were between 47 and 236 pmol/L (64 and 320 ng/L). Levels were lowest
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.