What is folate deficiency?

Updated: Nov 03, 2020
  • Author: Katherine Coffey-Vega, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Folate (vitamin B9) is an essential water-soluble vitamin that occurs in fruits, green leafy vegetables, liver, and other foods. [1] Folic acid, the synthesized form of folate, is present in fortified foods (eg, breads, pasta) and supplements; however, the terms folate and folic acid are often used interchangeably. [2]  Folate deficiency can result from inadequate diet, diseases that inhibit folate absorption, certain drugs, and congenital disorders; it may also be secondary to vitamin B12 deficiency. Alcoholism, pregnancy and lactation, hemolytic anemia, and dialysis can lead to folate deficiency. [1]

Presenting features of folate deficiency include the following:

  • Glossitis
  • GI signs and symptoms (anorexia, nausea, vomiting, abdominal pain, diarrhea)
  • Manifestations of anemia
  • Neuropsychiatric symptoms (eg, cognitive impairment, dementia, depression)
  • Patchy hyperpigmentation, especially particularly at the dorsal surfaces of the fingers, toes, and creases of palms and soles.
  • Low-grade fever

Folate deficiency in pregnancy can result in birth defects (anencephaly and spina bifida), which underlies the strong recommendation for folic acid supplementation in women of reproductive age. [2]

See Presentation for more detail.

A low serum folate level is suggestive of folate deficiency, but is not diagnostic. Testing to rule out cobalamin deficiency is very important because deficiency of folic acid and vitamin B12 produce overlapping neurologic manifestations, and both cause megaloblastic anemia. If there is strong clinical suspicion of folate deficiency but the serum folate level is normal and cobalamin deficiency has been ruled out, the red blood cell folate level may be measured. See Workup for more detail.

The dosage of folic acid needed to prevent or reverse folic acid deficiency varies with the clinical circumstances. Referral to a dietician may be indicated to ensure that the patient has appropriate dietary intake of folic acid. Fruits, vegetables, and fortified foods constitute the primary dietary source of folic acid. See Treatment and Medication for more detail.

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