MTHFR isoform carriers. 5-MTHF (5-methyl tetrahydrofolate) vs folic acid: a key to pregnancy outcome: a case series.

The conventional use of large doses of folic acid (5 mg/day) has become obsolete. Regular doses of folic acid (100-200 μg) can be tolerated in the general population but should be abandoned in the presence of MTHFR mutations, as the biochemical/genetic background of the patient precludes a correct supply of 5-MTHF, the active compound. A physiological dose of 5-MTHF (800 μg) bypasses the MTHFR block and is suggested to be an effective treatment for these couples. Moreover, it avoids potential adverse effects of the UMFA syndrome, which is suspected of causing immune dysfunction and other adverse pathological effects such as cancer (especially colorectal and prostate).