Vitamin B12: Benefits, Sources, and Deficiency Risks During Pregnancy and Breastfeeding

If you’re pregnant, trying to conceive, breastfeeding, or you’ve recently given birth, you’re likely aware of the essential vitamin folic acid—also called folate, or vitamin B9.

Studies show that babies born to mothers with folate deficiency are at a higher risk of having neural tube defects—that’s why all women who are trying to get pregnant, or who are pregnant, are recommended to take folic acid.

Vitamin B12 is a close relative to folic acid.

This essential vitamin is crucial for development of healthy nerve tissue, for brain function, and for red blood cell production. Vitamin B12 deficiency can result in anemia and potentially irreversible neurological problems.

The good news is, if you aren’t vegan, you’re most likely getting enough of this essential vitamin. If you are vegan, you can take vitamin B12 supplements or fortified foods to fill your recommended daily intake.

Here are the ins and outs of vitamin B12—everything you need to know about this essential vitamin for healthy pregnancy and breastfeeding:

What is vitamin B12?

Vitamin B12 is a water-soluble essential vitamin—meaning, it dissolves in water and must come from an outside source, because it cannot be synthesized by the body.

Vitamin B12 can be stored in the body for many years—that is why vitamin B12 deficiency is relatively rare. The body will absorb as much vitamin B12 as it needs, and the rest will be passed through urine.

What role does vitamin B12 play in the body?

Vitamin B12 is used for many functions in the body including red blood cell formation, cell metabolism, nerve function, and production of DNA. It also helps with the absorption of folic acid.

Red blood cells are constantly being produced in the body, and this process would not be possible without vitamin B12. This is especially important for a pregnant woman, whose plasma volume will increase by up to 50%, and red blood cell count by up to 30% during pregnancy.

Vitamin B12 consumption is also important for breastfeeding mothers—especially if the baby is exclusively breastfed. B12 is passed on to the baby through breastmilk—but in very small quantities, and infants require 0.4 micrograms (mcg) of vitamin B12 daily up to 6 months old, and 0.5 mcg from 7-12 months old.

How much vitamin B12 do I need?

According to the National Institutes of Health, the recommended dietary allowances for vitamin B12 are as follows:

0-6 months: 0.4 mcg

7-12 months: 0.5 mcg

1-3 years: 0.9 mcg

4-8 years: 1.2 mcg

9-13 years: 1.8 mcg

14+ years: 2.4 mcg

Pregnant women: 2.6 mcg

Lactating women: 2.8 mcg

Which foods are good sources of vitamin B12?

Vitamin B12 is not available in plant-based foods. The best sources of this essential vitamin are animal products including meat, poultry, fish, shellfish, eggs, and dairy products. Some foods including soy products and rice beverages are fortified with vitamin B12.

Foods which contain the highest amounts of vitamin B12 include: beef liver, sardines, mackerel, lamb, wild salmon, fortified nutritional yeast, and feta cheese.

Vegans, or people who follow a plant-based diet plan should consider taking vitamin B12 supplements or fortified foods to achieve their daily recommended intake.

What are the risks of vitamin B12 deficiency?

At all ages, vitamin B12 deficiency can lead to anemia. It can cause memory and cognitive impairment—including dementia in the elderly—and in serious cases, permanent nerve and brain damage.

Vitamin B12 deficiency during pregnancy may be associated with higher risk of a baby being born with neural tube defect, according to the World Health Organization.

Vitamin B12 deficiency in children has a clear link with developmental delays, lower scores at school, and lower cognitive performance.

Who is at risk for vitamin B12 deficiency?

People who don’t eat animal products, including vegans and plant-based dieters are at risk for vitamin B12 deficiency. Luckily, there are many other ways to get vitamin B12 including eating fortified foods and taking supplements.

Exclusively breastfed babies whose mothers are vegan or vegetarian are at risk for not getting enough vitamin B12. As it is, breastmilk does not contain a lot of this essential vitamin, but breastmilk from vegan or vegetarian women contains even less. If you are vegan and exclusively breastfeeding, you may want to consider taking vitamin B12 supplements.

The elderly are also at risk for vitamin B12 deficiency, as they cannot absorb this vitamin as well as younger people can. People over the age of 60 are often recommended to take multivitamins—which include vitamin B12—for this reason.

Another group of people at risk for B12 deficiency are those with pernicious anemia—a condition in which people lack the protein intrinsic factor (IF) which plays a role in absorption of vitamin B12.

Anyone with a medical condition which interferes with nutrient absorption including people with small intestine problems, gastritis, celiac disease, or inflammatory bowel disease may be at risk for B12 deficiency.

What are the symptoms of vitamin B12 deficiency?

Because vitamin B12 deficiency can lead to anemia, it may result in fatigue, muscle weakness, heart palpitations, shortness of breath, and intestinal problems.

Other vitamin B12 deficiency symptoms include nerve problems like numbness and tingling; vision loss; depression; memory loss; behavioral changes.

The National Institutes of Health reports that during infancy, vitamin B12 deficiency can present as failure to thrive, movement disorders, developmental delays, and megaloblastic anemia.

How is vitamin B12 deficiency treated?

Fortunately, there are many treatment options for those with vitamin B12 deficiency. People who suffer from pernicious anemia or who cannot absorb nutrients properly for any other reason, may be given vitamin B12 injections followed by vitamin B12 nasal spray for long-term use.

Those who are deficient in vitamin B12 for dietary reasons can supplement with fortified foods, injections, or oral vitamin B12.

Unfortunately, effects of long-term vitamin B12 deficiency, like nerve damage, may be irreversible—so if you see any early signs of vitamin B12 deficiency, consult with your doctor right away.

How can deficiency be prevented?

Healthy, young individuals who eat animal products should not be concerned with vitamin B12 deficiency.

People on plant-based diets, people with medical conditions, the elderly, and pregnant and breastfeeding women should consult with a doctor to find out if vitamin B12 supplements are right for them.

Long-term vitamin B12 deficiency is very preventable, and short-term deficiency is treatable. Fortunately, most prenatal vitamins contain vitamin B12, so if you’re taking your vitamins daily, you shouldn’t worry too much about being deficient in B12.


  1. Office of Dietary Supplements. Dietary Supplement Fact Sheet: Vitamin B12. National Institutes of Health. Available at June 24, 2011; Accessed: December 5, 2015.


3. Ladipo OA. Nutrition in pregnancy: mineral and vitamin supplements. Am J Clin Nutr. 2000 Jul.               72(1 Suppl):280S-290S.

4.  MyPlate Dietary Guidelines. Available                   at . June 2011;

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