An interesting tidbit that you are probably not aware of. The folate metabolism markers are actually a couple of rna and dna building blocks that require proper function of the folate cycle, which is the left gear of the methylation cycle. That is what I talk about when I mention that methylation being optimal is required for cell construction and its the fast dividing cells that are hit the hardest by this. Those would be the cells that make up the lining of the gut and all the white blood cells (immune cells). The effects of this problem are even being studied for their involvement in cancer. Its no surprise your markers are low. Folinic acid, 200 mcg daily, is the supplement to take for this problem, which is common for those with SHMT mutations. Some do not tolerate folinic acid, it has been theorized that this is due to a possible MTHFS mutation. The possible temporary bad effects arent bad enough to stop anyone from trying it if they think they need it.