Supplementation Possibly Helpful
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.
Methotrexate is called a "folate antagonist" because it prevents the body from converting folate to its active form. In fact, this inactivation of folate plays a role in methotrexate's therapeutic effects. This leads to an interesting Catch-22: methotrexate use can lead to folate deficiency, but taking extra folate could theoretically prevent methotrexate from working properly.
However, evidence suggests that individuals who take methotrexate for rheumatoid arthritis, juvenile rheumatoid arthritis, or psoriasis can safely use folate supplements.
Not only does the methotrexate continue to work properly, but its usual side effects may decrease also.
For example, in a 48-week double-blind placebo-controlled trial of 434 individuals with active rheumatoid arthritis, use of folate helped prevent liver inflammation caused by methotrexate.
Other side effects did not improve. A slightly higher dose of methotrexate was needed to reach the same level of benefit as taking methotrexate alone, but researchers felt this was worth it.
In the study just described, folate supplements did not help reduce the incidence of mouth sores and nausea. However, in other studies folate supplements did reduce these side effects, both in individuals receiving methotrexate for rheumatoid arthritis
and in those with psoriasis.
In addition, two studies of individuals with rheumatoid arthritis found that use of folate supplements corrected the methotrexate-induced rise in homocysteine without affecting disease control.
Folate supplements have only been found safe as supportive treatment in the specific conditions noted above. It is not known, for example, whether folate supplements are safe for use by individuals taking methotrexate for cancer treatment.