eileen

By Chandra Shekhar
NEWS
Vitamin D protects the skin?
Sunlight-induced vitamin D triggers an immune response in the skin, a finding that adds to an ongoing debate over the potential benefits of sun exposure

[Published 29th January 2007 06:31 PM GMT]

Vitamin D generated by sunlight may help protect the skin from cellular damage, including damage caused by sunlight itself, suggests a new study published in this week's Nature Immunology. The researchers found that dendritic cells can convert vitamin D3 -- generated under the skin by sunlight -- into its active hormonal form, and induce T cells to migrate to the skin.

"It's a new action for a chemical we've known to be present for a long time," said Clay Cockerell, a dermatologist at the University of Texas Southwestern Medical Center at Dallas, who was not involved in the study. "We may eventually find that [the T cell response] is protective in some way against skin cancer."

However, this does not mean that more time in the sun is good for the skin, Cockerell stressed. On the contrary, he said, the study implies that excessive sun exposure could trigger a cutaneous inflammation -- providing yet another reason to stay out of the sun.

Previous studies found that vitamin D3 generated under the skin by the sun's ultraviolet rays can be converted into its active form, calcitriol (1,25 dihydroxy-vitamin D3), by enzymes in the liver and kidneys. The new study shows that human dendritic cells could accomplish the same conversion without involving the endocrine system at all. "We propose that the whole thing could be happening in the skin itself," first author Hekla Sigmundsdottir of the Stanford University School of Medicine told The Scientist.

In 2004, research showed that vitamin A could induce T cells to move to the gut. Since the receptors for vitamins A and D are very similar in structure, and the chemokines expressed by epithelial cells in the gut and skin are also closely related, Sigmundsdottir and her colleagues hypothesized a similar T cell homing function for vitamin D, but with the skin as the target.

Using a chemotaxis assay on a co-culture of T and dendritic cells, they showed that vitamin D did attract T cells towards CCL27, a chemokine expressed by skin cells. Indeed, vitamin D not only activated the T cells' skin-homing receptor CCR10, it suppressed the corresponding gut-homing receptor CCR9 that vitamin A activates. "The two vitamins seem to compete with each other," Sigmundsdottir noted.

Vitamin D2, the primary nutritional form of the prohormone, was much less effective in inducing CCR10 expression in T cells than vitamin D3, the sun-induced version. "A little sunshine may be good for your immune system," Sigmundsdottir concluded. "This is what attracts T cells to the skin."

This study adds to a long-standing debate between two research groups: Vitamin D experts, some of whom who argue some sun exposure may be beneficial, and dermatologists (such as Cockerell) who generally advise against any sun exposure, and recommend supplements to meet the body's vitamin D requirements. The new study determined, however, that the levels of vitamin D needed to initiate a T cell response exceed those found in normal serum, even when taking supplements. "This suggests that UV production -- leading to the high local vitamin D levels -- is necessary," said James Fleet of Purdue University in West Lafayette, Ind., who studies nutrition and vitamin D, but was not involved in the study.

Fleet offered a possible compromise -- a topical application of vitamin D, which would protect the skin without putting it at risk from sunlight exposure. (Fleet said he has no financial ties to companies marketing topical vitamin D products.) Sigmundsdottir acknowledged that topical vitamin D -- just like its sun-induced counterpart -- might also be able to draw T cells to the skin. That could perhaps explain why topical vitamin D is effective against psoriasis and other skin conditions, she added.

Chandra Shekhar
mail@the-scientist.com

Links within this article

H. Sigmundsdottir, et al., "DCs metabolize sunlight-induced vitamin D3 to 'program' T cell attraction to the epidermal chemokine CCL27," Nat Immunol, Jan 28, 2007.
http://www.nature.com/ni/index.html

Clay Cockerell
http://www.utsouthwestern.edu/findfac/contact/0,2359,11378,00.html

A. W. Norman, "Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D: integral components of the vitamin D endocrine system," Am J Clin Nutr, 67:1108-10, 1998
'http://www.the-scientist.com/pubmed/15485630

A. McCook, "Vitamin D expert loses post," The Scientist, April 16, 2004
http://www.the-scientist.com/article/display/22116

James Fleet
http://www.purdue.edu/aging/people/faculty/fleet.htm

M. Kira, et al., "Vitamin D and the skin," J Dermatol, 30:429-37, 2003
http://www.the-scientist.com/pubmed/12810989




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billable

Let the vitamin D shine in
Sunlight triggers nutrient: Are you getting enough?
By Deborah Kotz U.S. News and World Report
Article Last Updated: 01/28/2007 01:02:52 PM MST



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A single nutrient that keeps bones strong, wards off diabetes, and protects against tuberculosis, cancer, colds and the flu. Sound too good to be true? There's more: It's free. But you're almost certainly not getting enough.
Research on vitamin D has flooded out the past few months, linking a growing array of health ills to low levels of the nutrient. Scientists now know that the vitamin, which is naturally produced in skin exposed to the sun's ultraviolet rays, binds to cell receptors throughout the body and that a lack can cause various systems to malfunction.
In December 2006, for example, University of Pittsburgh researchers reported that a D deficiency doubles the risk of dangerous hypertension during pregnancy because the nutrient helps control a hormone affecting blood pressure. In March 2006, a study examining how the vitamin affects the pancreas' release of insulin found the risk of diabetes to be one-third lower in people with the highest levels than in those getting the least.
"The vitamin D story is becoming clear. I think it's very exciting," says Robert Heaney, a professor of medicine at Creighton University in Nebraska who's researched the nutrient's effects on the bones and who, like many researchers, now thinks supplements are a good idea.
Prior to the industrial revolution, humans had no trouble getting an abundance of the sunshine vitamin; a mere 10 to 15 minutes outdoors at midday gives the average fair-skinned person 10,000 international units.
That's far above the government's dietary recommendations of 200 IUs a day up to age 50, 400 IUs to age 70, and 600 IUs over 70. But most people nowadays spend little time outdoors, and food sources such as milk and salmon contain relatively modest amounts. What's more, the rash of new findings suggests to the experts that the guidelines are way too low.
"There's no one working in the field who thinks these levels still make sense," says Walter Willett, a professor of epidemiology and nutrition at Harvard University whose recent studies have focused on the connection between vitamin D and cancer.
Many people run particularly short during the winter, says vitamin D researcher Michael Holick, a professor of medicine at Boston University School of Medicine. That's because anyone living north of Atlanta makes little, if any, from the sun when the UV rays fall at too low an angle to penetrate the atmosphere.
Vitamin D is best-known for promoting bone health. It was first added to the milk supply in the 1930s to prevent the bone-deforming disease rickets, and it defends against osteoporosis by triggering the absorption of calcium into bone cells.
New evidence indicates that many people suffering symptoms of chronic fatigue syndrome and fibromyalgia actually have a painful softening of the bones caused by a D deficiency.
But having too little appears to cause the immune system to weaken. A landmark study published in the March 2006 issue of Science found that cells from African-Americans (whose dark skin doesn't efficiently absorb UV rays) churned out 63 percent less of a protein needed to fight off tuberculosis than expected. When added to the cells, vitamin D appeared to signal the cells to produce normal levels of the protein.
An immune-system link might explain why the flu seems to strike only during the winter. A review of more than 100 studies on vitamin D and respiratory diseases, published in a recent issue of Epidemiology and Infection, found that low levels probably allow the viruses to penetrate the immune system.
"It's the first comprehensive theory set forth to explain the seasonality of influenza," says vitamin D expert and lead author John Cannell, president of the Vitamin D Council and staff psychiatrist at Atascadero State Hospital in California. What's now needed, he says, is a trial to see if those exposed to flu viruses are less likely to come down with an infection if they take supplements.
The possibility intrigues researchers bracing for an outbreak of avian flu, which quickly kills by triggering an excessive immune response. Victims often suffocate when an onslaught of disease-fighting cells, known as a cytokine storm, results in a rapid buildup of fluid in the lungs. Experts think vitamin D might rev up the part of the immune system that prevents the germs from gaining entry to cells in the first place.

Sherin

I highly reccomend going to Dr. John Cannell's website, and signing up for his newsletters!
http://vitamindcouncil.com/

__________________
War does not determine who is right, war determines who is left.

eileen

A Little Sun Might Shield Against Skin Cancer


A Little Sun Might Shield Against Skin Cancer

It's a puzzle to scientists, but a new study suggests that the main cause of deadly skin cancer sunlight might also help protect against the disease yorum yazarkadaşına ilet

The key could lie in the amount of ultraviolet B (UVB) light the skin absorbs -- enough to stimulate a healthy, vitamin D-linked immune response in the skin but not so much that it boosts skin cancer risk.
"I do think that a little bit of sunlight is good for people, but I think that one of the problems that the American Cancer Society and dermatologists have is, how do you define what a little bit is?" said skin cancer researcher Marianne Berwick, chief of epidemiology at the University of New Mexico's Cancer Research and Treatment Center. "How do you tell people that it's OK to have a little bit of sunlight but not too much?"
In 2005, Berwick's team published a controversial study that found that melanoma patients with higher levels of daily sun exposure actually had better survival than patients who spent less time in the sun.
"I've been searching for an explanation for that ever since," she said.
Now, findings from a group led by immunologists at Stanford University may provide an answer. The study, led by professor of pathology Eugene Butcher, is expected to be published in the March issue of Nature Immunology.
In its study, the Stanford team worked with cells in the lab and discovered a biochemical chain of events that appears to link sunlight exposure to the skin's own immune defenses.
The researchers started from the notion that an inactive precursor of vitamin D, called vitamin D3, "is generated in the skin in response to sun exposure." That's been known for years. Specifically, a short-wavelength form of UV light, called UVB, is responsible for D3 generation.
D3 is inert and powerless, however. Through contact with various enzymes in the liver and kidneys, the body turns D3 into an active compound called 1,25(OH)2D3.
And that's where the immune-system connection kicks in, the Stanford authors said.
In their experiments, they found that the new compound "signaled (immune) T-cells," pushing them to migrate back to specific sites in the skin's epidermis. Once there, these powerful immune system agents stand on guard against infection and even cancer, the researchers said.
"So, the same wavelengths of sunlight that are most potent in inducing skin cancer -- UVB -- are also the wavelengths that produce this vitamin D precursor, D3," said Dr. Martin Weinstock, chairman of the skin cancer advisory group at the American Cancer Society. And it's D3 that starts the whole chain of events rolling.
Weinstock stressed that the Stanford study is far from conclusive, however, and should not be seen as an excuse to bake in the sun.
"We know that the sun is the major avoidable cause of skin cancer," he said. "This study is interesting and points to a productive area of research, both to confirm this in other settings and to flush out the implications of the finding. But does it really relate to skin cancers in real live people? We don't know."
"So, avoiding intense sun, protecting yourself when you're out in intense sun -- that's still our [cancer society] recommendation, and this is not going to change that," said Weinstock, who is also professor of dermatology and community health at Brown University.
Kathleen Egan, a professor of epidemiology at the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla., agreed that the study findings are "tantalizing" but need further study.
Especially since the release of Berwick's melanoma study, "there's been an awful lot of questions about how -- or if -- vitamin D has a part to play in potentially offering some [cancer] protection under some circumstances," she said. "But it's very difficult to tease out, because the main human source of vitamin D is, in fact, sunlight exposure, which is also the most important risk factor for melanoma."
Nutritionists have known for decades that sunlight stimulates vitamin D production in the skin. In fact, this natural process is the body's major source of the nutrient. A proper amount of vitamin D is crucial to bone health, "and there's also a bunch of evidence that vitamin D may have a role in preventing colon cancer, although there's still some controversy about that," Weinstock said.
So, how much sunlight is enough to get the ideal amount of vitamin D? Katharine Tallmadge, a Washington, D.C., dietitian and a spokeswoman for the American Dietetic Association, suggests that most people can probably get the U.S. Department of Agriculture's recommended 400 daily IUs of vitamin D by spending a half-hour to an hour outside per day. Egan agreed. She said it's not difficult for people to soak up the sun's goodness without boosting their cancer risk. In response to even a moderate amount of sunlight, "the skin actually creates an amazing amount of vitamin D," Egan said. "It doesn't take much exposure to make enough of the vitamin D that's certainly needed to preserve bone health, for example."

billable

Same way you tell them it's OK to have a little bit of beer but not too much, it's OK to have a little bit of salt but not too much, it's OK to have a little bit of tylenol but not too much, it's OK to have a little bit of wine but not too much...

eileen

the old saying too much of a good thing is bad for you? ;)

lewdyju

Eileen- Thanks for putting up research with current articles! I feel like most of them I have read are from a few years back! :) UV Avantage articles are from 2005 in their latest news section. I know there is a lot out there to be read and thanks for posting them!

__________________
www.hotgloss.com
www.myspace.com/endlesssuntanningsalon

eileen

http://www.earthtimes.org/articles/show/27424.html

Immune cells' reaction to sunlight studiedPosted on : Mon, 05 Feb 2007 14:07:02 GMT | Author : Science News Editor


News Category : Science (Technology)



STANFORD, Calif., Feb. 5 U.S. medical scientists say they have discovered immune cells travel to protect the outer layers of the skin in response to sunlight-induced vitamin D.
Eugene Butcher and colleagues at the Stanford University School of Medicine say the immune cells express enzymes that convert an inactive form of vitamin D -- which is synthesized by skin cells upon sun exposure -- to an active form that triggers expression of certain homing receptors on the surface of effector T cells. Those receptors, say the researchers, can draw T cells to the skin's surface where they participate in immune surveillance and maintain barrier function.
The study suggests brief periods in the sun to generate the precursor form of active vitamin D might be beneficial by eliciting immune cells to skin tissues where they can ward off potential opportunistic pathogens and help repair ultraviolet light-induced damage.
The research is detailed in the March issue of Nature Immunology.