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 5 years’ worth of B12 and several months’ supply of folate in the liver, deficiencies and their associated symptoms can take months to years to manifest in adults. Infants and children, however, will show signs of deficiency more rapidly as they have not yet established extensive reserves.
Over time, a deficiency in either B12 or folate can lead to macrocytic ('large cell') anaemia, a condition characterised by the production of fewer, but larger red blood cells resulting in a decreased ability to carry oxygen. Due to the anaemia, patients may be weak, light-headed, tired and short of breath. A deficiency in B12 can also result in varying degrees of neuropathy (nerve damage that can cause tingling and numbness in the patient’s hands and feet) and mental changes that range from confusion and irritability to severe dementia.
Pregnant women need increased amounts of folate for proper development of the baby. If a woman has a folate deficiency before pregnancy, it will become worse during gestation and may lead to premature birth and neural tube birth defects, such as spina bifida, in the child.