system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does fair skin help people in environments with low sun absorb Vitamen D when the color white reflects light while the color black absorbs light? Does skin work differently?
gpt
Sunlight isn't beaming vitamin D into the skin, it is catalyzing the generation of the vitamin from precursors within the cells of the skin. Pigment in the skin blocks UV light before it can penetrate deep enough to cause that reaction as well as damage skin cell DNA.

The greater absorption of light of dark pigmented skin then doesn't imply an increase in the vitamin D production but rather a decrease.