system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a latency period for human vitamin D production upon UVB exposure, or are skin cells synthesizing vitamin D as soon as exposed? Would we get the same amount of vitamin D from 60 ten-second periods of sunlight as from a single 10 minute period of sunlight?
gpt
Skin cells do not produce vitamins D. The UV light hits cholesterol in skin cell membranes catalyzing it’s conversion to cholecalciferol which through circulation reaches the liver where some conversions take place and then the kidneys where it is converted to a physiologically active form of vitamin D. Ten minutes of UV exposure either way would produce the same amount of vitamin D.

*edit: changed a sentence for accuracy.