I've been on various methylation protocols since late 2013. In early 2014 I experienced my first side-effects from methylfolate. I've been reading like crazy on this forum about Freddd's active B12 protocol. I was really grateful to find out about the link between B12 and potassium. I was experiencing a feeling of dizziness as though not enough oxygen was getting to my brain, as well as pain in my fingers and toes. It took me about a month to realize methylfolate was the cause. I took the dose down from 800mcg to 400mcg, and that resolved the dizziness and finger/toe pain. I was also experiencing blood pooling in my feet, which my primary care doc diagnosed as venous insufficiency. It was worst first thing in the morning. My feet would turn blue or purple after a few seconds of standing or sitting still. The only way to keep the blue and purple feet and pooling blood away was to walk around. It would feel, when I first started walking after sitting and standing, like I was walking on glass for a few seconds, until the blood worked it's way up. At the worst, I was getting really painful sores on a couple toes. It took me a year to realize the venous pooling was connected to methylfolate, too. I took the dose down to 200mcg, and the feet became less painful, but blood still pooled. I've since stopped the methylfolate completely, just in the last month, and my feet have almost no pain, though blood still pools in them and they still turn blue, albeit a lighter blue than before. I don't read these symptoms on Freddd's symptom list that corresponds to different nutrient deficiencies, so I have no idea what to think. Interestingly, the dizziness and blood pooling issues seem to occur regardless of the type of folate, whether methylcobalamin or folic acid. (I haven't tried folinic in a while.) My serum folate is crazy high, and RBC folate is in the upper-middle range, so I look folate-sufficient in blood testing. I am A1298C heterozygous, so no severe MTHFR mutations. In April, I developed tingling in some fingers and toes, which spread to hands and feet in May. Now I have a loss of sensation in a stocking/glove distribution, and feeling of transient sunburn in hands, feet, arms, legs, face. Also, my feet feel very cold much of the time, much colder than they actually are if I feel them with my hands. I have no idea what the peripheral neuropathy has to do with methylfolate, if anything. If I go by Freddd's symptoms list, this would seem to reflect methylcobalamin deficiency, and yet my serum B12, MMA, and Hcy are all fantastic. Still, I'm upping my B12 in hopes of having the peripheral neuropathy resolve. I wondered if anyone has any idea why methylfolate (or folate in general) would cause blood to pool in your feet, and dizziness like your head lacks oxygen. Has anyone else experienced that? I'm at a loss, since the venous insufficiency isn't mentioned anywhere as a methylfolate side-effect, but in my case it's definitely related in some way to methylfolate. Thanks for any input, thoughts, help! I don't s'pose @Freddd still posts on here and helps people?! That would be amazing.