Just "D" Facts about Vitamin D

Benefits of Moderate UV Sunshine Exposure

Sun and Skin

Posted by D3forU on March 23, 2008

 

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There’s more fuel for the debate over the risk of skin cancer versus the benefits of vitamin D produced in our skin by sunlight. As this ScienCentral News video explains, it turns out that vitamin D might actually help the skin protect itself. Vitamin D and SunlightVitamin D has long been known to be important for helping our bodies absorb calcium and maintain strong bones, and a host of other benefits of vitamin D have been revealed in recent years.

Our bodies’ main source of the vitamin is our own skin, which produces it in response to UV rays in sunlight. But, why? Stanford University pathology researchers have made two important discoveries about how vitamin D produced in the skin by sunlight can trigger a protective immune response in the skin itself.

Hekla Sigmundsdottir and colleagues in Eugene Butcher’s Stanford University lab studied immune system cells called T lymphocytes, or T-cells, which circulate in our bodies and attack foreign or abnormal cells.

 
   
 

Sigmundsdottir Researcher
Hekla Sigmundsdottir, Stanford University

“In order for them to do their job, they have to know that there’s a danger, and that’s the job of another type of cells called dendritic cells,” Sigmundsdottir explains. “These dendritic cells scan the body and when they find something, they eat it up and then go to the T-cells and the T-cells then judge if this is harmless or something harmful that needs to be responded to. But the body is a big place and scientists have wondered, do they get some extra help to find the site more quickly. And that’s where the vitamin D would come in,” she says.The researchers isolated T-cells with dendritic cells and exposed them to different forms of vitamin D, including vitamin D3 from sunlight and vitamin D2, which is the type often added to milk and other foods. They found that, contrary to scientists’ beliefs, dendritic cells in the skin can convert vitamin D produced by sunlight into its active form. And they found that the active form triggers the protective T-cells to travel to the skin.

 
   
  Sigmundsdottir says the process was most efficient with vitamin D produced from sunlight. “Vitamin D that we obtain through the diet seems to be less effective than the vitamin that is generated in the sun,” she says.As they wrote in the journal Nature Immunology, the research could help explain why vitamin D is important to our skin’s immune system functions.“I think just the fact that the vitamin D can attract or draw T-cells towards the skin is a function that’s needed, I think that’s why we make vitamin in the skin,” says Sigmundsdottir.

TCells
The researchers isolated T-cells, shown here in blue, with dendritic cells and exposed them to different forms of vitamin D.
image: Hekla Sigmundsdottir

It’s also a surprise that vitamin D can be activated in the skin. Scientists have long known that vitamin D produced in sunlight has to be converted by the body into its active form in order to be useful, but it was thought that that only happens in our liver and kidneys.

 
   
  “What we find in our study is that if you isolate these helper cells or these dendritic cells from the skin, they can do it themselves, indicating that it does not have to go through the liver or the kidneys to be converted to the active form,” explains Sigmundsdottir.Put together, the discoveries suggest our skin has evolved a clever trick to protect itself. While she cautions that her research is preliminary and the team is at work on further studies, “I think a little sunshine is good for you,” she says. “I think the reason we make vitamin D in the skin indicates that it’s there for a reason.”Sigmundsdottir also points out that it’s too soon to know if this process may protect skin from the harmful effects of sunlight itself. “We are now in the process of examining this further,” she says, “but there are many other reasons why we would need enhanced immunity in the skin. There’s infections, there is all kind of exposure to harmful substances in the environment …”

And sun worshippers beware: Sigmundsdottir means it when she says “a little” sun exposure is good, because too much sun is still bad for you.

How much?

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Sunscreen blocks out the UVB light that triggers vitamin D production in skin. But it only takes 10 to 15 minutes of unprotected sun exposure a couple of times a week to make enough vitamin D for your body’s needs.More sunlight than that doesn’t make more vitamin D, but it can increase your risk of skin cancer and other skin damage. Dermatologists also warn that a tan is evidence of skin damage– good reasons to use sunscreen if you are going to spend more time than that in the sun.

This research was published in Nature Immunology, March 2007, and was funded by the National Institutes of Health (NIH), the Department of Veterans Affairs, FACS Core Facility of Stanford Digestive Disease Center, the Arthritis Foundation and Deutsche Forschungsgemeinschaft.

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One Response to “Sun and Skin”

  1. […] TV Pool Thai Series Video: TV Pool Thai Series Video WordPress Blog wrote an interesting post today onHere’s a quick excerptSun and Skin Posted by Tan Man on March 23, 2008 There’s more fuel for the debate over the risk of skin cancer versus the benefits of vitamin D produced in our skin by sunlight. As this ScienCentral News video explains, it turns out that vitamin D might actually help the skin protect itself. Vitamin D and SunlightVitamin D has long been known to be important for helping our bodies absorb calcium and maintain strong bones, and a host of other benefits of vitamin D ha […]

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