One Common Mistake That Will Foil Your Vitamin D Supplement Benefits – Mercola
Without Magnesium, Vitamin D Supplementation May Backfire
“As many as 50 percent of Americans taking vitamin D supplements may not get significant benefit, as the vitamin D simply gets stored in its inactive form due to magnesium deficiency”
Dr. Mercola also mentions the importance of increasing Vitamin K2 when increasing Vitamin D
Includes a review of
Role of Magnesium in Vitamin D Activation and Function
Which is in Vitamin D Life – see below
* Magnesium is vital to Vitamin D in 4 places (maybe 8) – March 2018 * A previous study found that one molecule of Vitamin D consumes 8 molecules of Magnesium

Vitamin D Life has long estimated that
Achieving a good level of Magnesium will boost Vitamin D levels by about 30%
About 1 in 300 people get pains in their body when increasing Vitamin D due to a lack of Magnesium
Magnesium is one of the many reasons for low response to Vitamin D
Reasons for low response to vitamin D
Note also: Constipation sometimes occurs with High Vitamin D and low Magnesium