Are We Missing Vitamin B12 Deficiency in the Primary Care Setting?

Rebecca Hilgen Bryan, MSN, APRN


Journal for Nurse Practitioners 

In This Article

Folic Acid Supplementation Masking B12 Deficiency

Folic acid works in conjunction with B12 for DNA synthesis. Folic acid deficiency causes macrocytic anemia but never neurologic deficits. Common causes of folic acid deficiency include poor diet and alcoholism. Since January 1998, the US Food and Drug Administration has required all enriched cereal/grain products to be fortified with folic acid, with the goal of reducing neural tube congenital defects.[10] Nutritionists have expressed concerns that folic acid fortification masks B12 deficiency, and a 2007 study demonstrated cognitive impairment in patients with high folate status in the presence of low B12. These patients were anemic without macrocytosis.[10] The authors suggest that excess folic acid precipitates both hematologic and neuropsychiatric manifestations of B12 deficiency. Interestingly, folic acid conferred cognitive protection in the presence of normal B12 levels. The point here is that folic acid supplementation in the presence of B12 deficiency may actually aggravate neurological symptoms.