Are pregnant women getting enough vitamin B12?

During pregnancy there is a significant increase in the nutrient requirements of the mother and developing baby.   We often hear of folic acid but another important one is vitamin B12, also known as cobalamin.  A recent study in Canada evaluated Vitamin B12 levels in pregnant women that is often underrepresented in national surveys.

Vitamin B12There are many benefits of vitamin B12 including maintaining healthy nerve cells, producing DNA and RNA (the body’s genetic material.  Another critical role is to help make red bloods and help iron work better in the body.

Another function of vitamin B12 is to lower levels of homocysteine in your blood.

High levels of homocysteine have been associated with heart disease with some health providers suggesting patients increase vitamin B12 and folic acid as ways to reduce homocysteine.

The 368 women evaluated in the study were represented from diverse geographic origins:

  • 45% white
  • 17% Asian
  •  9% Latin American
  • 7% black
  • 6% South Asian
  • 16% other

Here were some of the results from the study in subjects during early pregnancy (12-16 weeks): 

  • 16.9% were ‘deficient’ in B12 (<148 pmol/L)
  • 35% were ‘marginal’ in B12 (148-220 pmol/L)

What are the symptoms of B12 deficiency?

Symptoms of B12 deficiency without adequate vitamin B12 can cause permanent damage including blindness, deafness, and dementia. Early symptoms could include tingling in the hands or feet.  Another symptom could be low red blood cell numbers which a doctor can diagnose and distinguish between that or a folic acid deficiency.

Does supplementation of B12 increase levels?

The results of this study found that higher serum levels of B12 were observed in patients during early pregnancy and at delivery compared to non-users.

What are natural sources of B12?

B12 is typically found in meats including shellfish, liver, fish, and crab.  Non-meat sources included fortified foods such as soy products and grains (e.g. bran, cereals, etc.).  Other sources of B12 include milk, yogurt, cheese and eggs.

Take away message:  Plant based foods are typically low in vitamin B12 unless they have been fortified. This vitamin often requires supplementation or modifying dietary choices to include foods that are high in vitamin B12.  During pregnancy there is an increased nutrition demand for the growing baby which is why supplementation with B vitamins is advised by health professionals.

Journal of Nutrition. 2016 Apr 13.

Jeremy Johnson, PharmD, PhD


Categories: Food, Plant Medicine, Vitamins