Vitamin D₃ Photosynthesis in Skin

7-Dehydrocholesterol → Previtamin D₃ → Vitamin D₃

Overview

UV-B radiation (280–315 nm) converts 7-dehydrocholesterol in the skin to previtamin D₃ through a photochemical ring-opening reaction. Previtamin D₃ then thermally isomerizes to cholecalciferol (vitamin D₃). This is the primary source of vitamin D for most people and requires about 10–30 minutes of midday sun exposure.

Everyday Example

Spending 15–20 minutes in midday sunshine produces about 10,000–20,000 IU of vitamin D₃, far more than any food source.

Industrial Importance

Vitamin D deficiency affects over 1 billion people worldwide, driving demand for supplements and UV-fortified foods.

Properties

Type: Photochemical
Reversible: No
Energy: Endothermic

Related Reactions

Chlorophyll Fluorescence Cis-Trans Isomerization of Retinal Dye-Sensitized Solar Cell (Grätzel Cell) Firefly Bioluminescence (Luciferin Oxidation) Luminol Chemiluminescence Ozone Decomposition by UV Ozone Formation by UV Light Photocatalytic NOx Removal Photocatalytic Water Splitting (TiO₂) Photochemical Cycloaddition ([2+2])

Frequently Asked Questions

What is the equation for Vitamin D₃ Photosynthesis in Skin?

The balanced equation is: 7-Dehydrocholesterol → Previtamin D₃ → Vitamin D₃.

What type of reaction is Vitamin D₃ Photosynthesis in Skin?

Vitamin D₃ Photosynthesis in Skin is a photochemical reaction.

Is Vitamin D₃ Photosynthesis in Skin exothermic or endothermic?

Vitamin D₃ Photosynthesis in Skin is endothermic (absorbs energy).