People with dark skin can need up to six times more sun exposure than people with pale skin to make the same amount of Vitamin D.

If a person with very pale skin needs about 10 to 15 minutes in the midday summer sun to get their daily dose of Vitamin D, someone with very dark skin might need anywhere from 30 minutes to two hours. This difference is entirely due to how much light gets past the melanin in the skin. In northern countries, this means dark-skinned individuals rarely get enough strong sunlight during the autumn and winter months to make any Vitamin D at all.