Folate (Folic Acid) 

Folate (folic acid), with  vitamin B12,  is necessary for  the formation  of normal red blood cells and the synthesis of DNA (deoxyribonucleic acid), which  is the genetic material of cells.  Folate is also necessary  for normal development of a fetus's nervous system.  A low intake of folate may increase  the risk  of bone fractures  in older adults. Whether folate supplementation can improve cognitive function  in older adults remains unclear. 

In  the United States,  folate is added  to enrich foods made from grains.  Folate in supplements or in enriched foods  is easier  for the body to absorb than the folate that occurs naturally in food. 

Folate Deficiency 

• Not eating enough raw leafy  vegetables and citrus fruits can cause folate deficiency. 
• Anemia can develop, causing fatigue, paleness, irritability, shortness  of breath,  and dizziness. 
• A severe deficiency may result  in a red and sore tongue,  a reduced sense  of taste, weight loss, depression, tingling or loss  of sensation in the hands and feet, muscle weakness, loss  of reflexes, difficulty walking, confusion,  and dementia. 
• The diagnosis is based on blood tests. 
• Folate supplements taken by mouth usually correct  the deficiency. 

Because  the body stores only a  small amount  of folate, a diet lacking in folate leads  to a deficiency within a few months. Folate deficiency  is common because many people  do not eat enough raw leafy vegetables or citrus fruits. Also, prolonged cooking destroys much  of the folate  in food. Common causes  of deficiency include undernutrition and alcoholism, particularly when combined. Alcohol consumed in large amounts interferes with  the absorption and processing (metabolism)  of folate. Malabsorption disorders interfere with absorption  of folate. Certain anticonvulsants (such as  phenytoin and phenobarbital  and drugs used to treat ulcerative colitis (such as sulfasalazine ) decrease  the absorption of this vitamin. Methotrexate (used to treat cancer and rheumatoid arthritis), triamterene (used to treat  high blood pressure), metformin (used  to treat diabetes), and trimethoprim-sulfamethoxazole (an antibiotic) interfere with the metabolism  of folate. 

Women who are pregnant or breastfeeding and people undergoing dialysis may develop this deficiency because their need  for folate is increased. 

Folate deficiency causes an anemia similar to that due to vitamin B12 deficiency. 

Symptoms 

Anemia develops gradually  and may be more severe than symptoms suggest. Fatigue may be the first symptom. In addition  to the general symptoms of anemia (such as paleness, irritability, shortness of breath, and dizziness), folate deficiency, if severe, may result  in a red and sore tongue,  a reduced sense  of taste, weight loss,  and depression. If a pregnant woman has folate deficiency, her infant may have a birth defect of  the spinal cord or brain (neural tube defect). 

Diagnosis 

If a blood test detects large red blood cells in people who have anemia or who  are undernourished, doctors measure the folate level  in a blood sample. A low level indicates this deficiency. Doctors also measure  the vitamin B12 level  to rule out vitamin B12 deficiency because this deficiency can also result  in anemia  and large red blood cells. 

Prevention  and Treatment 

As a preventive measure, people who are taking drugs  that interfere with  the absorption or metabolism  of folate should take a folate supplement. Women  who are pregnant or who could become pregnant should take  folate supplements  to reduce  the risk  of having an infant with a birth defect. Women who have had a baby with a neural tube defect are often prescribed higher doses of  folate. Folate supplementation  has not been proven to reduce cardiovascular disease but may reduce strokes. 

Treatment consists  of taking daily doses of  a folate supplement by mouth. 

Folate Excess 

Folate  is generally not toxic. If people  with vitamin B12 deficiency take very high doses  of folate, doctors  may be delayed in recognizing  the nerve damage due to  vitamin B12  deficiency. Because  the diagnosis is delayed, nerve damage may be more severe  and more difficult  to treat. 

Notes: Dr. Nelson Crumfield

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EditText of this page (last edited June 8, 2010)