So, I wanted to do everything in a controlled, methodical way, but that ship has sailed. It was becoming clear a month or more ago that my major symptom of Oxalate dumping (chronic diarrheal) was possibly also what you call a paradoxical folate insufficiency, which is to say, not enough methyl B-12 to receive the methyl-folate I was taking. I was still trying to sort all this out when I found myself in the middle of it. Whoops. The Country Life Coenzyme B-Complex I was taking pulled a fast one on me sometime last year and switched out the Cyano-Cobalamin and Folic Acid (not that this was benefitting me, I now realize) for the active forms of both: 800 mcg Methyl-Folate and 500 mcg Methyl B-12. (All true, I've spoken to the company) I'd been taking this supplement for at least a decade and it was the last thing I suspected over the last year as some symptoms worsened--pain and muscle tightness--and my worst--atrial fibrillation--came and went...after a long, exhausting addition of low a dose beta blocker and supplemental magnesium, a small bit of iodine (225 mcg, I think, or whatever is the RDA), and a good probiotic. But then I kept visiting this sight and reading posts and trying to figure out this methylation stuff and how it might pertain to the mystery of my SNPs. It all felt overwhelming. I decided to get to that place @Freddd recommends of the low dose lower Bs and then move on to the @Sherpa recommendation for additional B-2 to iron out my Homozygous MAO. But I couldn't get to that because the withdrawal symptoms I had from going off the B-Complex have been a roller coaster ride of alternating depression, exhaustion, insomnia, muscular weakness and, worst of all, the slow re-entry of the heart stuff. PVCs at first, then the afib. All of these responded when I re-introduced the B-Complex--just one instead of the daily two--and I'd return to my usual, acceptable limping along for some days till that was too much and I'd go cold turkey till that stopped working and for a couple of weeks I threw in a single B-Complex once a week or so, each time with diminishing returns or increasing symptoms, until the final straw, anxiety within hours of taking the supp, followed by increasing diarrhea, and waking at night after an hour of sleep with atrial fibrillation. Oy. It was clear this wasn't working. Last Saturday I decided to bite the bullet--or in this case the methyl cobalamin--and took a jagged little piece of the pill (about 1/5) and stuck it up in my cheek. But only for a few minutes. Really. I took it out before it was half dissolved. After all, my husband who knows well my hyper-sensitivities joked that the best way to take it would be to put it on a nearby plate, wait a minute and push it away. So what might I have gotten from this approximate 200mcg dose? Maybe 100 mcg, or according to Freddd about 30mcg absorbed. At most. But more than I was getting from one-percent absorption of the Country Life's 500 mcg--even back when I was taking two pills a day. Well, the energy was pretty great. I went for a walk in the woods, cleaned house for two hours, ignoring my pain, took a nap for over an hour (unheard of on Folate), had a nice evening, went to bed and slept like a log for three hours, got up and ironed for a couple of hours (this middle of the night wakefulness is my pretty normal sleep disruption), went back to sleep for another two hours and woke up feeling very heavy and drugged, this time with the most disruptive atrial fibrillation I've ever had. I dutifully took 350 mg of potassium and the same of magnesium, but neither helped. My heart managed to convert on its own over two hours later in the Emergency Room of the local hospital. So, that was clearly too much B12, right? My husband thought the low B Complex (Nature Made) was where I ought to hang for a bit and I agreed. I had one night's respite--PVCs, but no afib, not too bad. Energy yesterday and off to sleep by 11. Then awake at 11:45 with a less wild afib...not so scary this time as I'd learned long ago that if I just sat up and drank bentonite clay water and did deep breathing, it would settle down. Not that I could actually lie down. It was a night of accommodating my heart (that sounds so sweet!)--sitting up, finding a suitably distracting book to read, finally falling asleep for an hour and a half or so wedged against a pile of pillows, before my heart woke me again. Just irregular bumps. After more bentonite clay I may be able to sleep for another two or three hours if I'm lucky. (Well, that didn't happen) But what now? It's pretty clear to me I need the B-12. I even googled some info about the relationship between afib and low B-12. But How much? I guess I need to go to @caledonia's "Start Low and Go Slow". Also I keep thinking that I may have been dehydrated the other night. I'd been adding more potassium over the last week or so (is it true that this isn't so much of an issue if I'm not currently taking the active folate?). And I recently read a thread about the autonomic nervous system and deep sleep and low blood pressure (my tendency) and heart irregularities. I was wondering if the B-12 put me into a deeper sleep and somehow with lowered bp that affected my heart. Or. Do I take a smaller amount of the Methyl-B12 before breakfast, then go back to the Country Life B-Complex, but at 1/2 of one pill, keeping the low Bs low and giving me 200 mcg of Methyl-folate. Would the two active forms help each other? The B 12 from the paradoxical Folate deficiency (and chronic diarrhea) and the Folate from that deep B12 heavy, deeper sleep? Well. So sorry for the length here. But I know many of you have far more experience than I, and possibly some thoughts that might help me with my Indecision... Thank you all.