Vitamin D

Matthew Capowski

Staff member
This is going to be a long thread. Vitamin D is a wonderous molecule with many benefits.

Peter Bergman, Anna-Carin Norlin, Susanne Hansen, Rokeya Sultana Rekha, Birgitta Agerberth, Linda Björkhem-Bergman, Lena Ekström, Jonatan D Lindh, Jan Andersson. Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention study. BMJ Open, 2012; 2: 6 e001663 DOI: 10.1136/bmjopen-2012-001663

Mayo Clinic. "Vitamin D toxicity rare in people who take supplements, researchers report." ScienceDaily. ScienceDaily, 30 April 2015.

Americans have low vitamin D levels, research shows, and as a result, vitamin D supplement use has climbed in recent years. Vitamin D has been shown to boost bone health and it may play a role in preventing diabetes, cancer, cardiovascular disease and other illnesses. In light of the increased use of vitamin D supplements, researchers set out to learn more about the health of those with high vitamin D levels. They found that toxic levels are actually rare.

Effects of vitamin D supplementation on intestinal permeability, cathelicidin and disease markers in Crohn’s disease: Results from a randomised double-blind placebo-controlled study [PDF file of study]

The above study finds that 2000IU/day for 3 months helped reduce both inflammation in Chrohn's disease and reduced intestinal permeability.

Vitamin D Status and Rates of Cognitive Decline in a Multiethnic Cohort of Older Adults:

Low VitD status was associated with accelerated decline in cognitive function domains in ethnically diverse older adults, including African American and Hispanic individuals who exhibited a high prevalence of VitD insufficiency or deficiency. It remains to be determined whether VitD supplementation slows cognitive decline.

Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level:

A letter to the editor about preventing respiratory infections that discusses the virtues of Vitamin D:

Large, single-dose, oral vitamin D supplementation in adult populations: a systematic review.

Safety of High-Dose Vitamin D Supplementation: Secondary Analysis of a Randomized Controlled Trial

Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths

How true is this? I tried to look into this and found:

"Thus, vitamin D at physiological doses may enhance magnesium absorption in non previously vitamin D-depleted pigs fed diets with abundant magnesium. This nutritional situation may help explain the predominant bone-resorbing effect of vitamin D supplementation."

And then there is some other research about magnesium potentially being necessary to make vitamin D bioavailable.

This one study says "and taking large doses of vitamin D can induce severe depletion of Mg" but I don't see more details:

So at what levels of vitamin D intake do we have to worry about this?
Paul Bergner in his excellent book on minerals states "High intakes of calcium, protein, vitamin D, and alcohol all increase the magnesium requirement." So I think it's fair to say that there's truth to taking into consideration magnesium when doing high doses of vitamin D. Where exactly to draw the lines, though, I'm unsure.