Vitamin D3
Cholecalciferol
More than a bone supplement. Vitamin D3 functions as a hormone precursor in the body and deficiency is directly correlated with low testosterone in men. Foundation doses it at 5,000 IU for a reason.
What it is
A fat-soluble vitamin produced by the body in response to sunlight exposure. Most men living and working indoors are chronically deficient. At the cellular level D3 acts more like a hormone than a vitamin, influencing hundreds of biological processes including testosterone production.
Why it's in Foundation
Vitamin D3 deficiency is one of the most common and most correctable contributors to low testosterone. Studies show men with optimal D3 levels have significantly higher testosterone than deficient men. Foundation doses at 5,000 IU - the level consistently shown to move deficient men into optimal range.
What the Research Shows
A 12-month randomized controlled trial showed men supplementing with Vitamin D3 had significantly higher testosterone levels compared to placebo. The correlation between D3 status and testosterone is one of the most well-documented relationships in men's hormonal health research.
View the Human Study
Testosterone correlation with Vitamin D3 status in men, published 12-month randomized trial
What to Expect
How it Works with Other Ingredients
Vitamin K2
K2 is essential for D3 to work properly - it directs calcium where it belongs and supports the hormonal signaling D3 activates.
Zinc
Both support testosterone production through separate mechanisms. D3 through hormonal signaling, Zinc through direct synthesis support.
Boron
Boron has been shown to increase the bioavailability of Vitamin D3, enhancing the hormonal effects of both ingredients.