Vitamin D3

The Sun Signal

Cholecalciferol · C₂₇H₄₄O

A sunlight-made signal that teaches the body how to handle calcium, bone, muscle, and immune readiness.

Vitamin D3 (cholecalciferol) is the form your skin makes from sunlight and the one supplements use. It governs how the body absorbs calcium and directs it to bone, supports muscle function, and keeps the immune system ready rather than overactive.