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Biology and You

You and Your Cells

How do skin cells synthesize vitamin D?

Vitamin D is crucial to normal bone growth and development. When UV light shines on a lipid present in skin cells, the compound is transformed into vitamin D. People native to equatorial and low-latitude regions of the earth have dark skin pigmentation as a protection against strong, nearly constant exposure to UV radiation. Most people native to countries at higher latitudes—where UV radiation is weaker and less constant—have lighter skin, allowing them to maximize their vitamin D synthesis.