The Pros and Cons of Folic Acid Supplements and What You Should Be Taking Instead

Folic acid is best known for its benefits in the prevention of spina bifida and other neural tube birth defects. Fortified cereal grains became mandatory about 15 years ago, and as a result the number of these birth defects decreased.

On the flip side, megadoses of this synthetic vitamin can cause an excess amount of unusable folic acid to remain in the bloodstream. This can stimulate the spread of preexisting cancers or mask a B12 deficiency.

Health Benefits of Folic Acid Supplements

During pregnancy, folic acid is used for the prevention of birth defects. It also supports a fetus' developing central nervous system.

It can help bring down homocysteine levels, reducing your risk of stroke or heart attack. Folic acid supplementation may also be helpful in the treatment of Alzheimer's disease.

Folic Acid Must Be Converted

Folic acid is a synthetic B vitamin. In order to be used by the body it must be converted intotetrahydrofolate. Your body makes tetrahydrofolate using an enzyme called dihydrofolate reductase (DHFR).

Prior to the mandatory fortification of grains, researchers found that rats could convert a significant amount of folic acid using DHFR. But in this case, what is true for the rat isn't true for the human being.

Scientists discovered later that humans produce less DHFR than laboratory rats. With only a small amount of the enzyme, not much folic acid can be converted into tetrahydrofolate. Unmetabolized folic acid is left to float around freely in the bloodstream.

High Levels of Unmetabolized Folic Acid Can Cause Health Problems

High amounts of folic acid in the bloodstream may exacerbate preexisting cancers and precancerous lesions. The immune system's natural killer cells may be compromised. High folic acid levels may also mask a B12 deficiency, which causes irreversible nerve damage that can become severe when left untreated.

Small Amounts of Folic Acid are Safe, Bioactive Forms are Best

A small amount of folic acid each day is more effective then megadoses. When less then one milligram is ingested, folic acid is more likely to be converted in most people. A combination of dietary supplements and fortified foods that goes above this amount may elevate the level of unmetabolized folic acid in your bloodstream.

If you want to take higher amounts of folic acid during pregnancy, or for other therapeutic effects, active forms of the vitamin are safest and most beneficial. Tetrahydrofolate or 5-methyltetrahydrofolate (5-MTHF) will not lead to elevated levels of unmetabolized folic acid. They are both natural forms that your body can assimilate and won't cause unwanted side effects that can be caused by synthetic folic acid.