Folic Acid

Folic acid is a vitamin that provides many health benefits. While it is most commonly known for its benefits in pregnant women, the vitamin may also play an important role in cancer and heart disease. Folic acid is found in many "fortified" foods and is also available as supplements. Side effects that may occur with high doses of the vitamin include diarrhea, hyperactivity, and rash.

 

What Is Folic Acid?

Folic acid (vitamin B9) is a water-soluble vitamin. It is added to many different "fortified" foods in the United States and is also available in supplement form. Most people are aware of the importance of this vitamin for pregnant women, but folic acid may also play an important role in cancer, heart disease, and numerous other medical conditions.
 
(Click Benefits of Folic Acid for more information on what it is used for.)
 

How Does Folic Acid Work?

Many of the effects of folic acid can be attributed to the two following actions:
 
 
  • DNA and cellular effects -- Folic acid is important for creating new DNA (the genetic material within cells). It also helps prevent errors when DNA is copied (when cells divide) and prevents other types of DNA damage. Although these actions are especially important during pregnancy, they are also important for children and adults as well. For instance, low folic acid levels can cause anemia by interfering with the normal division and maturation of red blood cells.
     
  • Homocysteine metabolism -- Folic acid helps to break down homocysteine, an amino acid that can cause problems if it builds up to high levels. In particular, it is thought that high homocysteine levels may contribute to problems such as cardiovascular disease or blood clots.
     

Is It Effective?

Folic acid is effective for several different uses. However, there is much controversy about some of these claimed uses, such as for cardiovascular disease (see Does Folic Acid Work? for more information).
 

Dosing Information for Folic Acid

Because the vitamin has been studied quite a bit, good information about dosing is available. For some of the less studied uses, the most effective (and safe) doses have not yet been established.
 
(Click Folic Acid Dosage for more information.)
 

Are There Side Effects?

Most people do not experience side effects with folic acid (at normal doses). However, high doses may be associated with side effects such as:
 
  • Abdominal (stomach) cramps
  • Diarrhea
  • Rash
  • Sleeping problems
  • Hyperactivity.
     
(Click Folic Acid Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
 

Drug Interactions

Folic acid can potentially interact with a few medications (see Folic Acid Drug Interactions).
 

Safety of Folic Acid

Normal doses are probably safe for most people, although high doses can cause problems. Some people may be more likely to experience problems due to the vitamin. Therefore, you should talk with your healthcare provider prior to taking it if you have:
 
Also, let your healthcare provider know if you are:
 
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Folic Acid Safety for more information, including any available warnings and precautions.)
 

What If I Take an Overdose of Folic Acid?

An overdose is unlikely to cause serious problems, since it is a water-soluble vitamin (which means that any excess is usually excreted in the urine). However, high doses have been reported to cause problems in some people.
 
(Click Folic Acid Overdose for more information.)
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;