Tag Archives: multiple sclerosis

More Truth about Sun Exposure

By Marc Sorenson, EdD… Sun exposure benefits…

A very important paper regarding the necessity for sun exposure has recently been published by the journal Medical Hypothesis.[1] It is entitled Regular sun exposure benefits health, and it discusses the pros and cons of sun exposure. One of the salient statements in the paper is that intermittent sun exposure may increase the risk of skin cancer, whereas regular exposure to sunlight might benefit health. For those of us who have for years studied the beneficial effects of sun exposure, the use of the word “might” is the only drawback to the statement. There is no doubt that for the majority of the population, regular sun exposure absolutely protects and enhances health.

Among the diseases mentioned as being reduced or prevented by regular sun exposure are the following:

  1. Cancers: Colon, breast, prostate and non-Hodgkin lymphoma
  2. Multiple sclerosis
  3. Hypertension
  4. Diabetes

As the authors mention, most of these positive effects of sun exposure were previously ascribed to Vitamin D, but they point out that immune system function is enhanced by sun exposure beyond the effects of vitamin D, and list other non-vitamin D benefits of the sun, including:

  1. Production of nitric oxide
  2. Production of melatonin
  3. Production of serotonin
  4. Regulation of the circadian clock

I have discussed most of these items on the Sunlight Institute web site, but it was good to see new research that, in particular, separated the health benefits of sun exposure from vitamin D production. The idea that has become popularized during the past decade, that all benefits of sun exposure come from increased vitamin D production, is simply not true and can lead to the supplementation of vitamin D as a “cure” for diseases that may not be influenced by that hormone.

Of course, vitamin D is an exceptionally important photoproduct, and the only natural way to attain it is by exposure to the sun or to other sources of UVB light (such as a sunlamp or a tanning bed). The beauty of using these sources, rather than a vitamin-D capsule, is that all of the benefits of nitric oxide, melatonin, serotonin and circadian entrainment are included in the package.

Safely enjoy the sun, and you then will also safely enjoy better health. Remember not to burn, and to gradually develop a good tan.

[1]  van der Rhee H, de Vries, E, Coebergh, J. Regular sun exposure benefits health. Medical Hypotheses 97 (2016) 34–37

Read More

More Research shows that Sun Exposure thwarts Multiple Sclerosis (MS).

By Marc Sorenson, EdD. Sunlight institute… sun exposure

 

If only those who suffer from MS had known the truth when they were younger! Getting plenty of sun exposure might have saved them from the ravages of this horrible disease. Much has been written about the influence of vitamin D on MS, and in this blog, I have pointed out that sun exposure may be more important than vitamin D. A new study conducted in Australia, and presented at the 32nd Congress of the European Committee for Treatment and in MS in Research in London, England, is interesting in the way it was conducted.[1]

By questionnaire, the researchers used past and present sun exposure as a surrogate for vitamin D levels and concluded that historical, but not current, vitamin D levels protect against MS.

This was an erroneous procedure to measure the influence of vitamin D levels on MS. It has already been established that sun exposure per se may be the operative habit that protects against MS. And in my opinion, vitamin D levels may only be surrogates for sun exposure, not vice versa. And, sun exposure probably mitigates MS, independent of vitamin D.

One of the most compelling papers on sun and MS was produced by Dr. Robyn Lucas and colleagues.[2] Here are the salient points in their report called Ultraviolet radiation, vitamin D and multiple sclerosis:

  • There is strong evidence from observational studies that low past sun exposure is associated with an increased risk of developing multiple sclerosis (MS).
  • Lower sun exposure or lower vitamin D status have been linked to more severe MS, that is, more frequent relapses and more rapid progression to disability.
  • Vitamin D supplementation trials for people with MS have shown improvement in immunological and MRI parameters, but with little convincing evidence of clinical benefit.
  • Higher levels of sun exposure may have benefits for MS-related immune parameters through both vitamin D and non-vitamin D pathways.
  • Exposure to ultraviolet radiation may result in immune tolerance that is beneficial for MS through upregulation of T and B regulatory cells, enhanced levels of cis-urocanic acid, alterations in dendritic cell trafficking as well as release of a range of other cytokines and chemokines.

To elucidate the last paragraph it is necessary to understand the vocabulary used. T cells are an integral part of the immune system that help rid the body of invading microorganisms. The regulatory T cells (or suppressor T cells) are a subpopulation of T cells which modulate the immune system and help prevent the body from attacking itself.[3] MS is another autoimmune disease in which the body is attacked its own immune system, which in the case of MS, destroys the myelin sheath. The regulatory, or T suppressor cells suppress these attacks, thereby preventing, abrogating or ameliorating the disease. B regulatory cells are also a part of the immune system and can, through their suppressive functions decrease inflammation, possibly through the production of anti-inflammatory cytokines.[4] Cis-urocanic acid is a chemical that is significantly lower in MS patients, and when stimulated by sun exposure, significantly reduces many indicators of MS.[5] [6] Dendritic cells are also messenger T cells that are essential in assisting sun exposure to decrease the immune response that effects autoimmune diseases.[7]

So let’s hear it for sun exposure as the very best therapy for MS. Be safe and don’t burn, and don’t use sunscreens, which can negate 99% of the sun’s vitamin D production.

[1] http://www.hcplive.com/conference-coverage/ectrims-2016/current-vitamin-d-doesnt-impact-ms-but-historical-exposure-does#sthash.ZF3nz3IN.dpuf

[2] Robyn M Lucas, Scott N Byrne, Jorge Correale, Susanne Ilschner & Prue H Hart. Ultraviolet radiation, vitamin D and multiple sclerosis. Neurodegener. Dis. Manag 2015 (epub ahead of print).

[3]https://en.wikipedia.org/wiki/Regulatory_T_cell (accessed November 24, 2015.)

[4] Min Yang, Ke Rui, Shengjun Wang and Liwei Lu. Regulatory B cells in autoimmune diseases. Cellular & Molecular Immunology (2013) 10, 122–132. Cellular & Molecular Immunology (2013) 10, 122–132.

[5] Jorge Correale and Mauricio Farez.S60 Multiple Sclerosis: Biomarkers: Clinical Phenotype Immune System Modulation in Multiple Sclerosis as a Result of Sun exposure: Role of cis-Urocanic Acid. Neurology April 6, 2012.  (names s

[6] Correale J, Farez MF. Modulation of multiple sclerosis by sun exposure: role of cis-urocanic acid. J Neuroimmunol. 2013 Aug 15;261(1-2):134-40.

[7] Breuer J, Schwab N, Schneider-Hohendorf T, Marziniak M, Mohan H, Bhatia U, Gross CC, Clausen BE, Weishaupt C, Luger TA, Meuth SG, Loser K, Wiendl H. Ultraviolet B light attenuates the systemic immune response in central nervous system autoimmunity. Ann Neurol. 2014 May;75(5):739-58.

Read More

Vitamin D Society recommends Summer Sun to build up D Levels.

By Marc Sorenson, EdD. Sunlight Institute…

Canada has a long season each year in which vitamin D from sunlight is not available. Due to the northern latitude of Canada, May through October is the only period when vitamin D can be produced in response to sun exposure to the skin. Therefore, a new press release from the Vitamin D Society recommends to protect health by building up vitamin D during the summer. Vitamin D from the summer sun helps to prevent serious diseases such as cancer, cardiovascular diseases, diabetes, multiple sclerosis and others.

Dr. Reinhold Vieth, the scientific advisor for the Society, states the following: We often assume that the health benefits of sunshine are solely due to vitamin D, but that is not proven yet.  In other words, it is likely that sunshine does more for our bodies than just produce vitamin D.”

Dr. Vieth is correct. Vitamin D is only one of several products of sun exposure. Others are nitric oxide, which helps prevent vascular problems, and serotonin and endorphins that enhance mood. It is likely that there are many more products of sun exposure that enhance human health.

The Society recommends 6 guidelines for safely enjoying the sun and its health benefits:

  1. Be moderate, and don’t burn.
  2. Sun exposure can produce vitamin D only during the mid-day hours, so be outside between 10 AM and 4 PM.
  3. Know your skin type and risk of burning. Red hair and very light skin predict a greater risk of burning. (Also remember that dark skin needs more sun exposure to produce vitamin D).
  4. A gradual build-up of a tan protects the skin from burning.
  5. When the skin begins to redden, it is time to stop the sun exposure.
  6. Frequent but shorter sun exposure times are better for producing vitamin D.

Since about 35% of all Canadians do not meet suggested vitamin D requirements, sun exposure is essential to reverse that statistic.

So Canadians, safely enjoy the sun this summer!

To read the entire press release, go to this link: http://www.vitamindsociety.org/press_release.php?id=44

Read More

A vitally important Study on Sunlight and Multiple Sclerosis (MS)

By Marc Sorenson, EdD, Sunlight Institute

Drs. Robyn Lucas and Prue Hart are researchers from Australia whom I have followed for years. They speak the truth about the benefits of sunlight and present their research in a cogent and easily understandable manner. Their recent paper, written with other colleagues, is no exception.[i] They show evidence that beyond vitamin D, other photoproducts such as regulatory cells, dendritic cells, chemokines and cytokines,
released from the skin following exposure to ultraviolet radiation, may have protective and ameliorating affects against MS.

Here are the salient points in their report called Ultraviolet radiation, vitamin D and multiple sclerosis:

  • There is strong evidence from observational studies that low past sun exposure is associated with an increased risk of developing multiple sclerosis (MS).
  • Lower sun exposure or lower vitamin D status have been linked to more severe MS, that is, more frequent relapses and more rapid progression to disability.
  • Vitamin D supplementation trials for people with MS have shown improvement in immunological and MRI parameters, but with little convincing evidence of clinical benefit.
  • Higher levels of sun exposure may have benefits for MS-related immune parameters through both vitamin D and non-vitamin D pathways. (emphasis mine)
  • Exposure to ultraviolet radiation may result in immune tolerance that is beneficial for MS through upregulation of T and B regulatory cells, enhanced levels of cis-urocanic acid, alterations in dendritic cell trafficking as well as release of a range of other cytokines and chemokines.

This research is important because it shows that sunlight exposure works on MS in several different ways, one of which may be the stimulation of vitamin D production.

As the authors state: Recognition of multiple pathways whereby exposure to UVR may affect the development of MS could mark the beginning of prevention activities through modulation of an environment risk factor and the development of new therapeutic compounds. The vitamin D star seems to be waning, despite considerable genetic evidence that vitamin D has a role in MS risk. Perhaps it is only one part of a more complex picture. New intervention trials, undertaken in parallel, of vitamin D supplementation and UV-B phototherapy, should provide more definitive evidence – at least for the risk of MS following CIS. A finding that sun exposure, through the entirety of its effects, does have clinical significance as an immunomodulator for the development of MS, offers one of the few opportunities to modify disease risk for MS.”

I have posted other blogs regarding sunlight and MS, indicative that sunlight has protective effects against that malady, beyond its ability to stimulate vitamin D production in the skin. This research by Lucas and her colleagues is important in that it defines some of the other mechanisms of sunlight exposure that could lead to the prevention and potential cure of the disease.

[i] Robyn M Lucas, Scott N Byrne, Jorge Correale, Susanne Ilschner & Prue H Hart. Ultraviolet radiation, vitamin D and multiple sclerosis. Neurodegener. Dis. Manag 2015 (epub ahead of print).

 

Read More

More Research on Multiple Sclerosis (MS): Highest Sunlight Exposure as a Teenager predicts later Age of Onset of MS.

By Marc Sorenson, EdD, Sunlight Institute

Although several of my posts on the Sunlight Institute have discussed sunlight and MS, this post will provide the results of the most recent paper that I am aware of, and it reviews some of the most important investigations showing that sunlight exposure is absolutely essential for preventing or mitigating the disease.

MS is a disease in which the myelin sheaths (nerve coverings and insulators) are destroyed, leaving nerves bare and susceptible to “short circuiting.” This process is known as demyelination. New research, which should surprise no one, demonstrates that teenagers who have the greatest exposure to sunlight have a delayed onset of MS as adults.[1] The study involved 1,161 Danish patients with MS who were given questionnaires regarding their sun-exposure habits and body-mass index (BMI) as teenagers. BMI is a measure of obesity (or the lack thereof). Besides sunlight, other vitamin-D predicting measures were also used to determine the probable cause of MS.

Interestingly, only sunlight exposure and lower BMI were associated with later age at the onset of the disease; other serum vitamin D predictors such as fish consumption did not show any association with MS. The authors still seemed to feel that vitamin D was the reason for the extended time before disease onset; however, that is unlikely, since other predictors of higher vitamin D levels showed no association. And, it has been shown that sunlight exposure has profoundly protective effects against MS, independently of vitamin D.[2] Researchers determined to find the mechanism by which sunlight exposure suppressed the disease and found that UV light selectively inhibits spinal cord inflammation and demyelination.[3] In that study, they performed an investigation in which ultraviolet radiation (UVR)—the same radiation that is found in sunlight and tanning beds—was administered to animals who suffered from experimental autoimmune encephalomyelitis (EAE).  EAE is MS that has been deliberately induced in animals in a laboratory setting. The researchers found that the UVR treatments stopped inflammation and demyelination of the spinal cord by inhibiting a chemical known as a chemokine, also known as a cytokine. Chemokines are the cause of the inflammation and autoimmune attacks that result in MS. The MS-ameliorating effects in the study were directly initiated by UVR, independent of vitamin D.

Stunningly, another study by some of these same investigators determined that vitamin D was actually necessary for EAE to take place![4]  Mice that lacked the vitamin D receptor, which causes vitamin D deficiency, had a markedly lower risk of developing EAE. In those mice that had receptors but were simply vitamin D deficient, the development of EAE was also partially suppressed. I do not look on this research as proving that vitamin D sufficiency leads to MS, but it certainly indicates that sunlight exposure, independent of vitamin D, is absolutely critical to prevent and ameliorate this frightening disease.

The bottom line? Be sure to get plenty of non-burning sun exposure!

[1] Julie Hejgaard Laursen, MD, PhD, Helle Bach Søndergaard, MSc, PhD, Per Soelberg Sørensen, MD, DMSc, Finn Sellebjerg, MD, PhD and Annette Bang Oturai, MD, PhD. Association between age at onset of multiple sclerosis and vitamin D level–related factors. Neurology 2015, Published online before print October 7, 2015.

[2] Becklund BR, Severson KS, Vang SV, DeLuca HF.  UV radiation suppresses experimental autoimmune encephalomyelitis independent of vitamin D production.  Proc Natl Acad Sci U S A. 2010;107:6418-23.

[3] Wang Y, Marling SJ, Beaver EF, Severson KS, Deluca HF. UV light selectively inhibits spinal cord inflammation and demyelination in experimental autoimmune encephalomyelitis. Arch Biochem Biophys. 2015 Feb 1;567:75-82.

[4] Wang Y, Marling SJ, Zhu JG, Severson KS, DeLuca HF. Development of experimental autoimmune encephalomyelitis (EAE) in mice requires vitamin D and the vitamin D receptor. Proc Natl Acad Sci U S A. 2012 May 29;109(22):8501-4.

Read More

More on the Effects of Sunlight beyond Vitamin D

By Marc Sorenson, EdD

Drs. Asta Juzeniene and Johan Moan wrote a paper in 2012 that beautifully summarizes the effects of sunlight beyond the production of vitamin D.[1] Here are the highlights of their paper, as stated in the abstract. They discuss the separate affects of Ultraviolet B light (UVB) and ultraviolet A light (UVA), which are, of course, components of sunlight.

  1. UVB induces cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning).
  2. UVB-induced, delayed tanning acts as a sunscreen.
  3. Several human skin diseases, like psoriasis, vitiligo, atopic dermatitis and localized scleroderma, can be treated with sunlight or artificial UV radiation (phototherapy).
  4. UV exposure can suppresses multiple sclerosis independently of vitamin D synthesis.
  5. UVA generates nitric oxide (NO), which may reduce blood pressure and generally improve cardiovascular health.
  6. UVA induced NO may also have antimicrobial effects.
  7. UVA induced NO may act as a neurotransmitter.
  8. UV exposure may improve mood through the release of endorphin.

It wasn’t mentioned in the paper, but we now know that sunlight also helps generate serotonin in the brain, which improves mood, and outside the body it is a potent disinfectant (see my recent blogs on those subjects). So those who claim that sunlight is harmful in any amount, must be living on a different planet. Embrace the Sun, but never burn.

[1] Asta Juzeniene and Johan Moan. Beneficial effects of UV radiation other than via vitamin D production. Dermato-Endocrinology 4:2, 109–117; April/May/June 2012.

Read More

When it comes to multiple sclerosis (MS), the sunshine vitamin may be even better for moms than for their babies.

By: Marc Sorenson, Sunlight Institute–

Dozens of observational studies have shown a correlation of sunlight and vitamin D deficiency to an increased risk of MS. It had been thought that babies and youngsters would be the hardest hit by these deficiencies, and many scientists encouraged pregnant mothers to keep their vitamin D levels high. This new research indicates that the real benefit may be a reduction in MS among the women who had the highest levels of D–in fact, a 61 percent reduction compared to those who had the lowest levels.

My opinion? The highest levels were probably not high enough; in other words, they were not optimized levels, which might have lowered risk much more. Although that is conjecture, the research on many diseases such as cancer and heart disease show that very high levels of vitamin D correlate to much lower rates of disease than the levels that are considered “normal” by the “experts.” How many diseases could be dramatically reduced by a return to the sunlight?

 

Read the article.

Read More

Lower sunlight exposure in pregnancy linked to multiple sclerosis risk

A child’s place of birth and their mother’s exposure to sunlight during early pregnancy could play an important role in later life multiple sclerosis risk, according to a new Australian study by the Murdoch Childrens Research Institute and The Australian National University.

The study, published online today by the British Medical Journal (bmj.com), found low maternal sunlight exposure – the main source of vitamin D – during the first four months of pregnancy increased the risk of multiple sclerosis in offspring in Australia.

Region of birth was also related to risk, with prevalence of multiple sclerosis highest in Tasmania and lowest in Queensland, suggesting exposure to sunlight during childhood and early adulthood may also be important.

Sunlight exposure levels during early pregnancy were reflected in a month of birth pattern, with Australian children born in November and December having a higher risk of developing multiple sclerosis than those born in May and June. This is consistent with previous research that found a reciprocal pattern in the northern hemisphere, where there were more cases of multiple sclerosis in people born in May and fewer in those born in November.

Study co-author Professor Anne-Louise Ponsonby said the findings indicated a need to review guidelines for vitamin D supplementation during pregnancy and childhood to help prevent multiple sclerosis.

“Low vitamin D levels can affect the development of the central nervous system or immune system,” Professor Ponsonby, of the Murdoch Childrens Research Institute, said.

“The higher risk of multiple sclerosis for people born in November and December is consistent with these infants having experienced lower levels of ultraviolet radiation during the first trimester.”

The study gathered data on the birth month, sex and region of birth of 1524 multiple sclerosis patients born in Australia between 1920 and 1950.

No association was found between daily ultraviolet radiation levels at the time of birth or in late pregnancy, and subsequent risk of multiple sclerosis. However, maternal exposure to low ultraviolet radiation levels during the first four months of pregnancy predicted a higher risk of multiple sclerosis. This effect persisted after adjustment for region of birth and appeared more important than the month of birth.

Multiple sclerosis is a disease of the central nervous system that affects an estimated 18,000 people in Australia.

Link: http://www.mcri.edu.au/pages/research/news/2010/4/lower-sunlight-exposur…

 

Read More

Life in the Sun Lowers Multiple Sclerosis Risk

By: Amanda Chan–

People who have had lifelong exposure to high levels of sunlight are less likely than people with less exposure to develop multiple sclerosis, a new study suggests.

The risk of having a preliminary symptom of multiple sclerosis decreased by 30 percent for every 1,000 kilojoules of exposure to ultraviolet light, the study said.

These levels of sun exposure were accumulated over a lifetime (you might be exposed to 6 kilojoules of UV light on a summer day), so people shouldn’t sit in the sun for extended periods of time without sunscreen and expect to lower their multiple sclerosis risk, said study researcher Dr. Robyn Lucas, a fellow at the National Centre for Epidemiology and Population Health at Australian National University.

“There is strong evidence that the risks of high doses of UV radiation in a single exposure greatly outweigh any possible benefits,” Lucas told MyHealthNewsDaily.

The benefits coming from higher vitamin D levels were already known, but because it was sun exposure that this study linked to decreased multiple sclerosis risk, it’s possible that only sun-generated vitamin D — and not that provided by food sources or vitamin D supplements — provides those benefits, Lucas said.

The findings of the study appear tomorrow (Feb. 8) in the journal Neurology.

The importance of sun exposure

Researchers looked at the sun exposure histories of 216 Australians, ages 18 to 59, who had an early sign of multiple sclerosis but were not diagnosed with the disease, as well as 395 people who did not have any MS symptoms. The participants reported how much sunlight they were typically exposed to, and the researchers also measured their skin damage from sun exposure and their melanin levels. The participants’ vitamin D levels were measured by blood tests.

Over their lifetimes, people in the study had been exposed to 500 to 6,000 kilojoules of UV light. Researchers found that those with the most skin damage from sun exposure were 60 percent less likely to have had a first sign of multiple sclerosis than people who had the least damage.

And people with the highest vitamin D levels were less likely to have a first sign of multiple sclerosis than people with the lowest vitamin D levels, the study said.

The researchers also found that multiple sclerosis was 32 percent more common in the Australian regions farthest from the equator than the regions closest to the equator — a difference they attributed to differences in sun exposure, vitamin D levels and skin type.

The secret to vitamin D’s effects

This study’s findings revealed the relationship between the first sign of multiple sclerosis, called the first demyelinating event, and sunlight, said study researcher Anne-Louise Ponsonby, an epidemiologist at Murdoch Children’s Research Institute in Australia.

The first demyelinating event can appear as a loss of sensation in a limb, blindness in one eye, or weakness in one limb that lasts more than 24 hours, Ponsonby said. Most people who have such an event will go on to develop multiple sclerosis in 10 years. The disease is diagnosed after a second event.

Vitamin D is known to affect immune cells, and the immune system plays a significant role in spurring multiple sclerosis, said Dr. Tom D. Thacher, an associate professor of family medicine at the Mayo Clinic in Rochester, N.Y., who was not involved with the study.

While the study showed that increased sun exposure is linked with a reduced risk of multiple sclerosis, it does not prove that vitamin D prevents the disease, said Thacher, who wrote an article on vitamin D insufficiency published last month in the journal Mayo Clinic Proceedings.

“Other factors besides vitamin D that are related to sun exposure could be responsible for protection from multiple sclerosis,” such as melanin production from getting a suntan, Thacher told MyHealthNewsDaily.

A study published last month in the journal Multiple Sclerosis found that people who had sufficient levels of vitamin D had higher levels of antibodies to the Epstein-Barr virus, which is linked to increased risk of multiple sclerosis.

“Low vitamin D may predispose people to certain viral infections,” said Dr. Ellen M. Mowry, author of that study and an assistant neurology professor at University of California, San Francisco, who was not involved with the new study. “Since some viral infections have been associated with MS risk, low vitamin D could also influence MS by this mechanism.”

Link: http://bit.ly/gRbqOr

Read More

UV Radiation, Not Vitamin D, Might Limit Multiple Sclerosis Symptoms

By Nathan Seppa April 24th, 2010; Vol.177 #9 (p. 9)

Ultraviolet radiation from sunshine seems to thwart multiple sclerosis, but perhaps not the way most researchers had assumed, a new study in mice suggests.

If validated in further research, the finding could add a twist to a hypothesis that has gained credence in recent decades. The report appears online March 22 in the Proceedings of the National Academy of Sciences.

Scientists have hypothesized that MS is rare in the tropics because people synthesize ample vitamin D from exposure to the UV radiation in equatorial sunlight. What’s more, MS is more common in the high latitudes of northern parts of Europe and North America than in regions farther south. That pattern has led to the assumption that higher levels of vitamin D might prevent people from developing MS, what became known as the latitude hypothesis.

But a direct cause-and-effect relationship between vitamin D deficiency and MS has never been established. In past experiments, giving vitamin D supplements to mice with an MS-like disease required giving the animals harmful amounts of the nutrient, notes Hector DeLuca, a biochemist at the University of Wisconsin–Madison.

“It just didn’t add up,” he says. “We decided to go back and see if maybe UV light by itself was doing something.”

In MS, the fatty myelin sheaths that insulate nerves in the central nervous system are damaged by attacks by the immune system. In a series of experiments in mice, DeLuca and his team induced a condition comparable to human MS by injecting the animals with proteins that instigate similar myelin damage.

The researchers exposed some mice to UV radiation before and after giving the animals the damaging injection. Another group of mice got the injection but not the UV exposure.

The mice exposed to UV rays suppressed the effects of MS-like disease better than the control mice, the researchers found, even though the amount of radiation wasn’t enough to greatly increase the animals’ blood concentrations of vitamin D.

In another test, the researchers gave injected mice varying doses of vitamin D supplements, but no UV radiation. The supplements failed to control the disease onset, severity or progression.

“We concluded that UV light is doing something beyond [making] vitamin D,” DeLuca says.

There’s no question that the latitude hypothesis has merit, says George Ebers, a neurologist at the University of Oxford in England. “MS risk is geographically related.” But that risk is more complicated than exposure to UV radiation during an MS attack, as this mouse model used. For example, previous research has shown that children in northern latitudes who are born in May, after their mothers had spent a winter with little sunshine, are more likely to develop MS than are kids born in November, he says.

Ebers notes that mice in this study were exposed or not exposed to UV over a matter of weeks and were in the throes of an MS-like disease during the study. “That’s completely separate … from the question of whether your risk is boosted or diminished by where your mother lived,” he says.

Apart from the timing issue, MS risk might well be influenced by a biological mechanism apart from vitamin D blood levels, but many questions remain, Ebers says. Those include how UV radiation might inhibit MS and, more specifically, what is the effect of UV rays in suppressing the immune system. “It’s quite possible that UV exposure will have a number of other mechanisms and be involved in hormonal circuits,” he says.

DeLuca and his colleagues speculate that UV radiation is playing a mysterious role in MS that is independent of vitamin D production. “We’re doing experiments trying to find out what it is,” he says.

Link: http://bit.ly/dtAO7v

Read More