It also decreased cortisol (stress hormone) levels and lower blood pressure. While this study was very small (13 people), other studies have shown that vitamin D3 improves exercise performance and increase muscle strength. It has also been shown that vitamin D3 inhibits the activity of the enzyme needed to make cortisol.
What was the average serum vit D levels at start and end of the trial in the 13 people tested? With 2000IU supplemented the average increase should have been around 10ng/L. I am very curious as to whether there is an observed threshold starting point whereby the 10ng/L increase (i’m assuming this value) made no difference or perhaps there is an increasing positive effect with higher serum vitD start points, given the same dose and overall net increase. Scott