13/08/2026
Vitamin D is not a crisis intervention.
Let me say that again.
If you wait until you get sick to take vitamin D, you've already lost the window.
Your white blood cells need vitamin D to make the specific proteins that kill infections. That process requires vitamin D to be present before the infection arrives.
Shoving down vitamin D capsules on day 2 of a cold with a gut that's already inflamed and absorbing poorly is mostly wasted effort.
The vitamin D you take today protects the you of next November.