Adequate vitamin B12 in human breast milk is essential for normal infant growth and development. Pregnant women in Tanzania were enrolled in a randomized, controlled trial to assess the effects of prenatal and postnatal B12 supplementation on human milk at six weeks and seven months postpartum.

The study in The American Journal of Clinical Nutrition reported that the prevalence of vitamin B12 levels below 310 mmol/L was 73.3 percent at six weeks and 68.4 percent at seven months postpartum.

Prenatal supplementation with vitamin B12 resulted in a significant increase in breast milk B12 levels. Postnatal supplementation of vitamin B12 significantly elevated levels in human milk at seven months.

The authors concluded, “ Prenatal maternal vitamin B12 supplementation has benefits on short-term [breast milk] status, and postnatal maternal vitamin B12 supplementation has benefits on long-term [breast milk] status.”

Vitamin B12 deficiency is very common, and it is crucial for fetal growth and the normal development of the nervous system. Deficiency during gestation can lead to lifelong problems, including poor growth and development as well as neurological and behavioral abnormalities that may not be reversible.

More information about B12 can be found in my book, Vitamin B12 for Health.