Question: What are optimal levels of B12? So there's a paper called the Pathophysiology of Elevated Vitamin B12 in clinical practice that PM Schoenfeld, another Masterpass member, had given me. And this paper is very interesting because it identifies a bunch of things that high B12 can be an indicator of, not a causal factor in but an indicator of problems. And it also disputes the low end of the range. So according to this paper, we really want B12 levels above 400 picograms per milliliter, which is 295 picomoles per liter. I believe picograms per liter is what most people's lab results come in. And that's like double what most labs are using for low levels at least at the time this paper was written. I believe it's like 1400 is where their cutoff flies for potentially indicating problems. Reference: https://academic.oup.com/qjmed/article/106/6/505/1538806 If you would like to be part of the next live Ask Me Anything About Nutrition, sign up for the CMJ Masterpass, which includes access to these live Zoom sessions, a private discussion group, premium features on all my content, and hundreds of dollars of exclusive discounts. You can sign up at https://chrismasterjohnphd.com/masterpass/ and use the code QANDA to get 10% off the membership for life. For the remainder of 2020, I will be working full-time on finishing my Vitamins and Minerals 101 book, while reserving a portion of my time for consulting clients. You can pre-order my book at https://chrismasterjohnphd.com/book. You can sign up for a consultation at https://chrismasterjohnphd.com/consultations. DISCLAIMER: I have a PhD in Nutritional Sciences and my expertise is in performing and evaluating nutritional research. I am not a medical doctor and nothing herein is medical advice.