Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.

Vitamin B12 Deficiency and Folate Deficiency

Print this article
Share this page:
Also known as: Cobalamin; Folic Acid

What are vitamin B12 and folate deficiencies?

B12 and folate are B complex vitamins that are necessary for normal red blood cell formation, tissue and cellular repair, and DNA synthesis. A B12 and/or folate deficiency reflects a chronic shortage of one or both of these vitamins. Since the body stores 3 to 6 years worth of B12 and about a 3 months' supply of folate in the liver, deficiencies and their associated symptoms can take months to years to manifest in adults. Infants and children will show signs of deficiency more rapidly because they have not yet established extensive reserves.

Over time, a deficiency in either B12 or folate can lead to macrocytic anemia, a condition characterized by the production of fewer but larger red blood cells, thus a decreased ability to carry oxygen. Due to the anemia, those affected may be weak, light-headed, and short of breath. A deficiency in B12 can also result in varying degrees of neuropathy or nerve damage that can cause tingling and numbness in the person's hands and feet. In severe cases, mental changes that range from confusion and irritability to dementia may occur.

Pregnant women need increased amounts of folate for proper fetal development.  Because of the added stress of rapidly growing cells (the fetus), increased amounts of folate are required. If a woman has a folate deficiency prior to pregnancy, it will be intensified during gestation and may lead to premature birth and neural tube birth defects, such as spina bifida, in the child. The number of neural tube defect cases decreased by 36% in the U.S. since focusing on folate supplements during pregnancy. Restless leg syndrome during pregnancy is another neurologic symptom associated with decreased folate. 

Next »