The Low Down on Folic Acid
How does it work?
Folic acid is a B vitamin needed for cell replication and growth. Folic
acid helps form building blocks of DNA, the body’s genetic
information, and building blocks of RNA needed for protein synthesis in
all cells. Therefore, rapidly growing tissues, such as those of a
fetus, and rapidly regenerating cells, like red blood cells and immune
cells, have a high need for folic acid. Folic acid deficiency results
in a form of anemia that responds quickly to folic acid supplementation.
In 1996, the FDA began to require that all enriched flour, rice, pasta,
cornmeal and other grain products contain 140 mcg of folic acid per 100
grams. Among people who do not take vitamin supplements, this amount of
food fortification has been associated with increased folic acid levels
in the blood and decreased blood levels of homocysteine.
Key Uses for Folic Acid
- Depression: A deficiency of folic acid can disturb mood; a
large percentage of depressed people have low folic acid levels.
- Gingivitis (periodontal disease) (rinse only): A 0.1%
solution of folic acid used as a mouth rinse (5 ml taken twice a day
for 30 to 60 days) has reduced gum inflammation and bleeding in people
with gingivitis in double-blind studies.
- High homocysteine (in combination with vitamin B6 and
vitamin B12): Folic acid is needed to keep blood levels of homocysteine
(an amino acid by-product) from rising. A growing body of evidence
suggests that an elevated homocysteine level is a risk factor for many
diseases, especially heart disease. Of the B vitamins with a role in
homocysteine metabolism, folic acid appears to be the most important in
lowering homocysteine levels for the average person.
- Pap smear (abnormal): Large amounts of folic
acid–10 mg per day–have been shown to improve the
abnormal Pap smears of women who are taking birth control pills. Folic
acid does not improve the Pap smears of women who are not taking oral
contraceptives.
- Pregnancy and postpartum support: The requirement for folic
acid doubles during pregnancy, while deficiencies of folic acid during
pregnancy are associated with low birth weight and an increased
incidence of neural tube defects (e.g., spina bifida) in infants. Most
doctors, many other healthcare professionals, and the March of Dimes
recommend that all women of childbearing age supplement with 400 mcg
per day of folic acid. If a woman waits until after pregnancy has been
discovered to begin taking folic acid supplements, it will probably be
too late to prevent a neural tube defect.
- Schizophrenia: People with schizophrenia may have a greater
tendency to be deficient in folic acid than the general population and
may show improvement when given supplements.
Other Potential Uses for Folic Acid
- Anemia
(for deficiency): Folic acid deficiency results in a form of anemia
that responds quickly to folic acid supplementation.
- Atherosclerosis and heart attack: While several trials have
consistently shown that folic acid lowers homocysteine levels, the
amounts used vary from study to study. Many doctors recommend
500–800 mcg of folic acid per day.
- Breast cancer (reduces risk in women who consume alcohol)
- Canker sores (for deficiency only)
- Celiac disease: The malabsorption that occurs in celiac
disease can lead to multiple nutritional deficiencies, including folic
acid deficiency.
- Colon cancer (prevention): Folic acid appears to protect
against alcohol-induced DNA damage. Increasingly, researchers believe
that folic acid may be able to protect against some of the colon
cancer-causing effects of alcohol.
- Preeclampsia:
In one preliminary study, women with high homocysteine and a previous
pregnancy complicated by preeclampsia who supplemented with 5 mg of
folic acid and 250 mg of vitamin B6 per day successfully lowered
homocysteine levels.
- Sickle cell anemia: Deficiencies of folic acid occur more
frequently in people with sickle cell anemia than in others and are a
cause of high homocysteine levels. A double-blind study of children
with sickle cell anemia found that children given 5 mg per day of folic
acid had less painful swelling of the hands and feet compared with
those receiving placebo, but blood abnormalities and impaired growth
rate associated with sickle cell anemia were not improved. These
amounts of folic acid are much higher than is typically used and should
only be taken under the supervision of a doctor. In the treatment of
sickle cell anemia, folic acid is typically supplemented in amounts of
1,000 mcg daily.
- Ulcerative colitis (UC): Studies have found that people
with UC who have been taking folic acid supplements or who have high
blood levels of folic acid have a reduced risk of colon cancer compared
with other individuals with UC. Individuals with UC who are taking the
drug sulfasalazine, which inhibits the absorption of folic acid, are at
particularly high risk of developing folic acid deficiency.
Where is it Found?
- Beans, leafy green vegetables, citrus fruits, beets, wheat
germ, and meat are good sources of folic acid.
How Much is Usually Taken?
- Most doctors recommend that all women who are or who could
become pregnant take 400 mcg per day in order to reduce the risk of
birth defects. Some doctors also extend this recommendation to other
people, as well, in an attempt to reduce the risk of heart disease by
lowering homocysteine levels.
- For people who frequently eat grain products, the amount
needed to be taken in supplement form may be lowered by approximately
100 mcg per day, because of the FDA’s mandated addition of
folic acid to many grain products.
Which Form of Folic Acid is Best?
- Folate naturally found in food is much less available to
the body compared with synthetic folic acid found both in supplements
and added to grain products in the United States.
Are
There Any Side Effects or Precautions?
- Folic acid is not generally associated with side effects.
However, folic acid supplementation can interfere with the laboratory
diagnosis of vitamin B12 deficiency, possibly allowing the deficiency
to progress undetected to the point of irreversible nerve damage.
Although vitamin B12 deficiency is uncommon, no one should supplement
with 1,000 mcg or more of folic acid without consulting a doctor.
- Folic acid is needed by the body to utilize vitamin B12.
- Proteolytic enzymes and antacids inhibit folic acid
absorption. People taking either of these are advised to supplement
with folic acid.
- Folic acid–containing supplements may interfere
with methotrexate therapy in people with cancer. People using
methotrexate for cancer treatment should consult their prescribing
doctor before using any folic acid–containing supplements.
- People with rheumatoid or psoriatic arthritis who are
taking methotrexate should supplement with relatively large amounts of
folic acid in order to reduce the toxicity of the drug. However, a
physician should be consulted to determine the proper way to combine
folic acid with methotrexate.
- A preliminary study showed that people taking diuretics for
at least six months had significantly lower blood levels of folic acid
as well as significantly higher levels of homocysteine, compared with
people not taking diuretics.
Potential adverse drug interactions
- Chemotherapy (Methotrexate only)
- Medroxyprogesterone (Cycrin®,
Depo-Provera®, Provera®): Folic acid may interfere with
the drug’s effects.
- Methotrexate (Abitrexate): Folic acid may interfere with
the drug’s anticancer effects. However, folic acid is often
recommended when methotrexate is being used for rheumatoid arthritis.
Consult a physician.
- Piroxicam (Feldene®): Folic acid may interfere with
the drug’s effects.
- Sulindac (Clinoril®): Folic acid may interfere with
the drug’s effects.
The information presented in this article is for informational purposes
only. It is based on scientific studies (human, animal, or in vitro),
clinical experience, or traditional usage as cited in each article. The
results reported may not necessarily occur in all individuals. For many
of the conditions discussed, treatment with prescription or
over-the-counter medication is also available. Consult your doctor,
practitioner, and/or pharmacist for any health problem and before using
any supplements or before making any changes in prescribed medications.