Can you please define mthfr deficiency?

When real, very rare: True deficiency in methylene tetrahydro folate (folic acid) reductase is an extremely rare, severe and obvious genetic illness. An aggressive lab is promoting testing widespread testing to see which of several common alleles people have at this locus. It's not clear to me that there's any real public or individual health benefit in this testing. All folks should get plenty of folate (folic acid), B12 & b6.

Methylfolate: MTHFR is a gene that codes for an enzyme that makes methylfolate. Mutation can cause decreased enzymatic function resulting in less methylfolate being produced. Not everyone who has MTHFR needs to supplement methylfolate. Those who eat plenty of raw fruit and vegetables may get adequate methylfolate from their diet.