Humans cannot produce folate and therefore rely on adequate dietary intake. Since the introduction of folic acid food fortification throughout the world, the prevalence of folic acid deficiency has decreased. However, certain population groups and health conditions may warrant increased folate intake from foods or folic acid supplements.
Folic Acid Deficiency Causes
The most common folic acid deficiency cause is a low daily intake from foods. This may be from a lack of fresh green vegetables, legumes, and enriched grains or from food processing or preparation. Prolonged storage and cooking can cause a 50% to 95% loss of folate.
Other factors that may cause folic acid deficiency are:
- Alcoholism: alcohol interferes with folate metabolism and increases folate breakdown
- Malabsorption diseases: such as celiac disease and gastric diseases that cause low stomach acid
- Pharmaceuticals: some drugs may impair folate absorption and inhibit folate metabolism
- Acquired folate malabsorption: a rare hereditary folate malabsorption
- Pregnancy, lactation and infancy: all have an increased folate requirement
- Kidney dialysis: increases folate excretion
- Other nutrient deficiencies: zinc, riboflavin (vitamin B2), niacin (vitamin B3) and vitamin B12. These may affect folate absorption and metabolism
- Age: the elderly are more susceptible due to low intake, malnutrition and existing medical conditions.
Folic acid deficiency poses a number of clinical and diagnostic challenges because in the early stages there may be no obvious signs of deficiency. It may take four months before any signs or symptoms.
Folic Acid Deficiency Symptoms
Folic acid deficiency causes very general symptoms such as:
- Fatigue and weakness
- Headaches and difficulty concentrating
- Palpitations
- Diarrhoea
- In the early stages, the tongue may be red and painful leading to a smooth shiny surface in the chronic stages of deficiency.
The Three Stages of Folic Acid Deficiency
At the first stage of deficiency the plasma folate levels fall. If the diet does not contain adequate folate, the red blood cell (RBC) folate levels drop after three to four months. With continuing deficiency, the bone marrow cells and other cells become affected. This is stage three, the clinical stage of folic acid anemia. It occurs after approximately four to five months of deficiency. Folic acid anemia is called megaloblastic anemia.
Folic acid functions in DNA synthesis and therefore cell division. Without this important vitamin, cells such as red blood cells produced in the bone marrow, fail to divide properly. RNA continues to form and build up producing excess haemoglobin. The RBC becomes an immature enlarged non-functioning cell often containing excess haemoglobin. This is megaloblastic anemia.
Certain factors confuse the diagnosis of folic acid deficiency anemia. The folic acid anemia is identical to the anemia of vitamin B12 deficiency. Therefore, it is very important to rule out vitamin B12 deficiency before taking folic acid supplements for anemia; otherwise, the megaloblastic anemia of vitamin B12 may go on unnoticed. In addition, the factors that lead to folate deficiency, such as poor diet, malabsorption and alcoholism, affect other nutrients as well, so singling out folic acid as the cause is often difficult.
Testing for Folic Acid Deficiency
Serum folate levels reflect recent changes in folate intake whereas RBC folate measures the folate stored in the body. RBC folate is a more reliable test. These tests are available through a standard blood test from the doctor.
High homocysteine levels may also reflect low folate status but it may also be indicative of vitamin B12 and vitamin B6 deficiency.
Resources:
Shils ME, Shike M, Ross AC, Caballero B, Cousins RJ. Modern Nutrition in Health and Disease. 10 ed. Maryland: Lippincott Williams & Wilkins; 2006.
Gropper S, Smith JL, Groff JL. Advanced nutrition and human metabolism. Belmont, CA: Thomson Wadsworth; 2005.
Johnson LE. Folate [monograph on online] 2007 April [cited 2008 November]
Gentili A. Folic Acid Deficiency. [monograph online] 2007 19 September [cited 2008 November]
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