|DROR, DAPHNA - Consultant
|Allen, Lindsay - A
Submitted to: Advances in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2018
Publication Date: 5/29/2018
Citation: Dror, D., Allen, L.H. 2018. Vitamin B12 in breast milk: a systematic review. Advances in Nutrition. 9:358S-366S. https://doi.org/10.1093/advances/nmx019.
Interpretive Summary: Vitamin B12 concentrations in human milk are sensitive to maternal B12 status, and B12 depletion or deficiency in infants results from a combination of low in utero storage of the vitamin and low milk B12 concentrations. Our laboratory recently developed and validated a new method for analysis of the vitamin in human milk – older methods largely produced erroneous values. The systematic review showed limitations in data due to problems with laboratory methods used for sample pretreatment and assay, a wide range of infant age at the time of milk collection, few longitudinal studies, and a lack of multi-center studies including populations of differing baseline intake and status. In women with deficient or marginal vitamin B12 status, maternal supplementation with physiological or pharmacological doses of vitamin B12 was effective in raising breast milk vitamin B12 concentrations. Future studies are needed to fill the identified gaps and to investigate correlations between breast milk vitamin B12 concentration and infant status, including neurologic and metabolic function.
Technical Abstract: Because of limited liver reserves at birth, infants are dependent on vitamin B12 in human milk to support tissue synthesis and normal neurological development. Consequences of infantile vitamin B12 deficiency resulting from maternal depletion during pregnancy or lactation include irritability, apathy, anorexia, failure to thrive, and gross developmental regression. To evaluate existing data on human milk vitamin B12 concentrations over the course of lactation, a systematic search of published literature was undertaken using the US National Library of Medicine’s MEDLINE/PubMed bibliographic search engine. Observational and intervention studies were included if research was original and vitamin B12 concentration in human milk was measured at one or more time points during the first twelve months of lactation. Of the 26 studies identified, only two were considered to be of high and one of moderate quality using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system. While absolute measurements of human milk vitamin B12 concentration using outdated analytical methodologies may be inaccurate, within-study trends suggest that vitamin B12 concentration is highest in colostrum and decreases to a potential nadir at 3-4 months postpartum. Vitamin B12 concentration in human milk is inconsistently correlated with plasma or serum vitamin B12 or maternal anemia but is positively associated with habitual vitamin B12 intake during lactation according to the majority of available data. Supplementation with 2.6-250 µg/d oral vitamin B12 during lactation is effective at raising human milk vitamin B12 concentration compared with controls provided that supplementation is continued until the point of sampling. Future studies are needed to determine optimal human milk vitamin B12 concentrations to support maternal and infant requirements, including infant neurologic and metabolic function