Possible Benefits and Risks
Folate (also known as folic acid) is a B vitamin that plays an important role in many vital aspects of health, including preventing neural tube birth defects and possibly reducing the risk of heart disease. Because inadequate intake of folate is widespread, if you are taking any medication that depletes or impairs folate even slightly, you may need supplementation.
Most drugs used for preventing seizures can reduce levels of folate in the body.
Phenytoin in particular appears to decrease folate levels by interfering with its absorption in the small intestine,
as well as by accelerating its normal breakdown by the body.
The low blood levels of folate caused by anticonvulsants can raise
levels, a condition believed to increase the risk of
Adequate folate intake is also necessary to prevent neural tube birth defects, such as spina bifida and anencephaly (absence of a brain). Because anticonvulsant drugs deplete folate, babies born to women taking anticonvulsants are at increased risk for such birth defects. Anticonvulsants may also play a more direct role in the development of birth defects.
However, there can be problems with using folate supplements. High folate levels may speed up the normal breakdown of phenytoin.
This can lead to breakthrough seizures.
For this reason, folate supplementation during phenytoin therapy should be supervised by a physician.