May 18, 2023·edited May 18, 2023Liked by Robin Whittle

I read a study on human participants that showed how high fructose corn syrup can impair conversion of Vit D3. Not sure if it would also apply to regular fructose from fruits or honey.

On the issue of conversion or utilization of Vit D3 to the active and hormonal forms, I've read bout the necessity of Magnesium for this. One suggested to get lots of ot it, as if there's no upper bound, while another study showed that there appears to be a optimal spot. The later case showed Mg below certain level (which most people who are not supplementing) resulted in lower D3 conversion, but too much Magnesium seems to also impair conversion. I will have to go back and find the study to see if it was just observational correlation or direct intervention testing on the subjects.

Also do you know about biotin interference in serum testing for 25-OH D3 levels? I think I will have to get my levels along with numerous other tests redone after I stop biotin supplementation for 4+ days. I had deficient D3 levels several years ago at 16 ng/mL. Then I started supplementing, got more sun exposure when I could, and got my levels up (mid-upper 40's). However, it went back down when retesting twice in the past couple years, though not down to the truly deficient level (at 37 ng/mL a year ago). I seem to have hard bringing it back up despite increasing supplementation a bit.

My only guess at this point is the biotin interference causing false results in the blood tests because that's what has changed in my regimen since then. See: https://chrismasterjohnphd.substack.com/p/biotin-causes-false-lab-tests

Expand full comment
May 17, 2023Liked by Robin Whittle

Is there a vit D intake chart that takes elderly hypo-intake into consideration?

Expand full comment

What about high levels of vitamin d causing hypercalcemia and therefore heart issues. I heard it's necessary to also take K2 to protect the heart?

Expand full comment