The most important things you need to know about the connection between the Sun, Ultra Violet Light and Vitamin D

This weekend was the first sunny, warm weekend we had in a while. I took the advantage of the sun and I got my coffee on the roof terrace. While sitting there in the sun I exposed both of my legs and arms to capture as much UV as possible. It was around 11 AM when we went there and we didn’t stay long… 30 min – max 1 h. But in this time, I manage to get some redness on my skin but the redness faded in the next hour after I get back in the house (they weren’t real sunburns). That was the perfect scenario for producing some Vitamin D.

The best source of Vitamin D is the sun, and particularly the Ultra Violet “light” is the one that stimulates the body to produce Vitamin D.

But first let’s understand some things about sun and Vitamin D…

  • There are 3 types of UV: UVA, UVB and UVC – they differ from the wave length they have

  • UVA – It penetrates deep into the layers of the skin. It creates free radicals and damage the collagen => creates wrinkles. It also activates special cells in the skin that creates the dark color pigment (melanin) => you get a tan. It is considered the main factor behind the skin cancer
  • UVB – penetrates less deeply into the layers of the skin. It can cause redness of the skin (sunburn – long exposure can also contribute to the formation of malignant skin tumors). * IT IS ONLY THE UVB FRACTION OF THE SUNLIGHT THAT GENERATES VITAMIN D *
  • Sunscreen creams block only the UVB => this allows us to stay in the sun without the visible burns, but without the benefit of the UVB and also the damage done by the UVA is not blocked.
  • The time when the greatest amount of UV light reaches the earth is between 10:30 AM – 3 PM (at this time of the day the UV passes through the thinnest layer of the atmosphere). In the morning and in the afternoon, the sun’s light has to pass through thicker layers of atmosphere, and only the UVA manage to pass this barrier in a significant amount and very little UVB. So, in the morning and in the evening, we can’t produce too much Vitamin D from sun exposure.
  • The amount of UV depends on the latitude you are located on Earth. At lower latitude, closer to Equator, the amount of UV is much higher than at higher latitudes like in Europe or North America (as you can see in the below picture).

  • The amount of Vitamin D you produce depends on how much skin is exposed to light. The more skin you have exposed, the more Vitamin D you produce. Try to have at least your arms and legs exposed to the light.

  • How much time you should get exposed to the light? 5-10 min twice a week with a big amount of skin exposed (naked) should be enough to generate enough Vitamin D that will match the supplementation of oral Vitamin D. But we can’t get naked every day :), so try to get more exposure (frequency) when less skin is revealed to the sun, at least 10 min every day.
  • People with darker skin need to get more sun exposure to get the same level as people with pale skin

Enjoy the sun!


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