Jul 24, 2022 • 8M

What's the difference between 25(OH)D and 1,25(OH)2D when it comes to the VDR?

Q&A Files #295 Early Release Podcast

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Episode details

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 from this batch here:

Questions on Vitamin D, Fatty Liver, HbA1c vs CGM, Turmeric and Testosterone, Fasting, and B6 Markers

In that batch of free episodes you will also find the answers to these questions:

  • 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

  • Why do my urinary B6 markers say I'm deficient if I'm supplementing and my plasma levels are high-normal?

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This snippet is from the April 13 AMA. The full recording and transcript is reserved for Masterpass members. Here is a preview of what’s included:

Ask Me Anything | April 13, 2022

Fat-soluble vitamins, prenatal nutrition, mixing glycine with aspirin, supplementing with alpha-ketoglutarate, nausea in pregnancy, and more.

The questions include:

  • 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.


I am not a medical doctor and this is not medical advice. My goal is to empower you with information. Please make all health decisions yourself, consulting sources you trust, including a caring health care professional.

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