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Folate deficiency

Last updated: February 5, 2021

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Folate (vitamin B9) is an essential coenzyme that enables critical biochemical reactions. Dietary sources include naturally folate-rich foods such as leafy green vegetables, fruit and liver, but also supplements and fortified foods. Malnutrition and excessive alcohol use are the most common causes of deficiency. Folate deficiency causes impaired DNA synthesis, which leads to megaloblastic anemia. The clinical picture of anemia is similar to that of vitamin B12 deficiency, although folate deficiency is generally not associated with neurological manifestations. Diagnosis is based on laboratory findings such as macrocytosis, hyperhomocysteinemia, and normal levels of methylmalonic acid. Therapy consists of oral supplementation.

Folate deficiency is the most common vitamin deficiency in the US.

Decreased folate levels leads to decreased levels of tetrahydrofolate. This, in term, leads to the following effects:

Unlike vitamin B12 deficiency, folate deficiency does not result in neurological symptoms.

If folate deficiency is suspected, always exclude the possibility of vitamin B12 deficiency.

  • Oral folate supplementation for four months or until hematologic recovery takes place
  • Nutritional counseling to increase folate intake

Because of the risk of neural tube defects, it is recommended that women planning to become pregnant initiate folate supplementation before conception.

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