What's the difference between 25(OH)D and 1,25(OH)2D when it comes to the VDR? | Masterjohn Q&A Files #295

Short answer: 25(OH)D is 1000 times weaker at activating the VDR than 1,25(OH)D, but 1000 times more abundant. This is why I advocate measuring both, and ultimately believe we need to create a calculated index of "biological vitamin D activity" from them. This is a clip from a live Q&A session open to CMJ Masterpass members. In addition to this episode, you can access five other free samples using this link: https://chrismasterjohnphd.substack.com/p/questions-on-vitamin-d-fatty-liver In that batch of free episodes you will also find the answers to these questions: What's the difference between 25(OH)D and 1,25(OH)2D when it comes to the VDR? Reversing Fatty Liver: How Long Does It Take? What if my A1C says I'm diabetic but my CGM says I'm fine? Will reishi, turmeric, or curcumin tank my testosterone? The 3 Phases of Fasting: And How to Get Kicked Out of Each One If you want to become a Masterpass member so you can participate in the next live Q&A, or so you can have access to the complete recording and transcript of each Q&A session, you can save 10% off the subscription price for as long as you remain a member by using this link to sign up: https://chrismasterjohnphd.substack.com/qanda Learn more about the Masterpass here: https://chrismasterjohnphd.substack.com/about This snippet is from the April 13, 2022 AMA. The full recording and transcript is reserved for Masterpass members. Here is a preview of what's included: How to balance vitamins E and K What prenatal vitamin do I recommend? Why does my smoothie make my hands cold? What type of choline to use? Is there an interaction between glycine and aspirin? What supplements can be used in the fasting state? How to manage protein intake within a small eating window on an intermittent fasting regimen? Looking at a study on calcium alpha-ketoglutarate supplementation. Should I take vitamin D for COVID if I easily get hypercalcemia from it? What to do about nausea in pregnancy? Brief questions on restless legs, exercise during fasting, puffy eyes, and health effects of spicy foods. Here's a link to the full AMA: https://chrismasterjohnphd.substack.com/p/ask-me-anything-april-13-2022 Access the show notes, transcript, and comments here . Chris Masterjohn, PhD, is the Founder and Scientific Director of the mitochondria test Mitome .