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Vitamin B12 in breastmilk supports child growth and brain development

Vitamin B12 in breastmilk supports child growth and brain developmentFetuses and children need various nutrients, including vitamin B12, to support the development of the body and brain. According to a study published in The American Journal of Clinical Nutrition, it is crucial to breastfeed the child for a period of at least six months to make sure it gets enough vitamin B12 from the mother’s milk. Most people get enough B12 from animal food sources. However, in countries and populations where people primarily consume plant-based diets, vitamin B12 deficiencies are common. The scientists behind the new study therefore recommend more focus on this specific area and recommend that pregnant and breastfeeding women take vitamin B12 as a supplement in case they don’t get enough from their diet.

Vitamin B12 is important for DNA synthesis, blood formation, energy levels, brain function, the nervous system, and our cognitive abilities. Lack of vitamin B12 during the first year of life may result in serious health problems such as anemia and impaired growth and development. Moreover, it can cause neurological and behavioral abnormalities that are irreversible.
The vitamin B12 status of a neonate depends on the vitamin content in the mother’s B12 status, and this is also the case during the first six months where the child should only get breastmilk. If the mother continues breastfeeding the child while introducing it to solid food, the breastmilk still represents a good source of B12. The mother has an increased need for vitamin B12 during pregnancy and breastfeeding to ensure that the baby gets what it needs.
The widespread problems with vitamin B12 deficiency in underdeveloped countries or areas with limited access to animal food sources is a serious health problem. The same is the case with mothers who prefer eating a plant-based diet and don’t take a vitamin B12 supplement.
In a part of Tanzania with limited resources where there is widespread vitamin B12 deficiency among mothers, a team of scientists from George Mason University in the United States wanted to determine the optimal vitamin B12 intake during pregnancy and breastfeeding. They recruited 412 pregnant women from Dar es Salam in Tanzania and followed them from week 12-27 of their pregnancy until six weeks after giving birth. The women were randomly assigned to a daily multivitamin tablet or matching placebo. Six weeks after delivery, part of the women were divided into two new groups, with one group receiving a larger daily vitamin B12 supplement (50 micrograms) and other vitamins, while the other group got matching placebo.
The scientists then analyzed the vitamin B12 content in the women’s breastmilk six weeks after delivery and again seven months after delivery in all 412 women.

  • B12 is the only B vitamin that is stored in the body.
  • A B12-depleted diet will cause the body’s reserves to dwindle.
  • Pregnancy and breastfeeding increase the need for B12 vitamin

B12 supplementation works differently during pregnancy and after delivery

The study showed that supplementation with vitamin B12 during pregnancy increased the B12 concentration in breastmilk until six weeks after delivery, but there was no effect seven months after delivery. High-dosed B12 supplementation after delivery increased the content of B12 in breastmilk for up to seven months after the child was born.
Based on their findings, the scientists conclude that B12 supplementation during pregnancy has a shorter effect on the B12 content in breastmilk, while high-dosed B12 supplementation after delivery has a longer effect on the B12 content in breastmilk.


Dongqing Wang et al. The effects of prenatal and postnatal high-dose vitamin B-12 supplementation on human milk vitamin B-12: a randomized, double-blind, placebo-controlled trial in Tanzania. The American Journal of Clinical Nutrition. 30 November 2023

George Mason University. How pre- and postnatal B-12 vitamins improve breast milk vitamin B12-levels, which supports infant brain. ScienceDaily December 1, 2023

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