Vitamin D: Sunshine and Skin Cancer

May 1, 2007

DasL wants to know how Vitamin D derived from sun exposure can prevent cancer when we have been told to cover up from the sun to prevent skin cancer. Marc answers DasL’s confusion in the comments section (see full exchange here).

So here is my interpretation. There are two types of skin cancer, melanoma and nonmelanoma. Nonmelanoma skin cancers are very common but rarely fatal. Malignant melanoma is very rare but deadly. Over-exposure (i.e. sun burns) can lead to skin cancer in general. Vitamin D protects against cancers that have a very high mortality rate, including malignant melanoma.

Vitamin D is produced in skin exposed to UV-B. The more common and abundant type of UV is UV-A which gives us a tan. UV-B levels are dependent on where the sun is in the sky. Highest levels occur at mid-day in the summer while typical Canadian UV-B levels are insufficient for 4-6 months of the year (winter).

The trick is to get UV-B exposure without getting burned. Short exposures at mid-day are ideal.

So how did the famously healthy Greenland Inuit get their Vitamin D? Food, of course. I’ll take a shot at Vitamin D in food in another post.

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2 Responses to “Vitamin D: Sunshine and Skin Cancer”

  1. das L Says:

    thx for the cLarification!


  2. […] D: Food Sources In my Vitamin D: Sunshine and Skin Cancer post I mentioned the Greenland Inuit and that they would have acquired all the Vitamin D they need […]


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