Folate, vitamin B12 and birth defects.Forum Nutr 2003; 56:45-9FN
While the evidence that folic acid/folate can prevent most cases of NTDs if taken periconceptually, the position is less clear with respect to OFCs. Some studies indicate a positive protection while others are negative. There are also conflicting reports as to whether or not the C677T variant of MTHFR increases risk. This is to be contrasted with NTDs where it clearly does.