Van alles m.b.t. Vitamine D

[vonneke]

http://www.medicalnewstoday.com/articles/172048.php

Multiple Health Concerns Surface As Winter, Vitamin D Deficiences Arrive

A string of recent discoveries about the multiple health benefits of vitamin D has renewed interest in this multi-purpose nutrient, increased awareness of the huge numbers of people who are deficient in it, spurred research and even led to an appreciation of it as "nature's antibiotic."

On issues ranging from the health of your immune system to prevention of heart disease and even vulnerability to influenza, vitamin D is now seen as one of the most critical nutrients for overall health. But it's also one of those most likely to be deficient - especially during winter when production of the "sunshine vitamin" almost grinds to a halt for millions of people in the United States, Europe and other northern temperate zones

Analogs of the vitamin are even being considered for use as new therapies against tuberculosis, AIDS, and other concerns. And federal experts are considering an increase in the recommended daily intake of the vitamin as more evidence of its value emerges, especially for the elderly.

"About 70 percent of the population of the United States has insufficient levels of vitamin D," said Adrian Gombart, a principal investigator with the Linus Pauling Institute at Oregon State University. "This is a critical issue as we learn more about the many roles it may play in fighting infection, balancing your immune response, helping to address autoimmune problems, and even preventing heart disease."

Those issues were just outlined in a new publication in Future Microbiology, a professional journal, on the latest findings on vitamin D research, at OSU and in many other programs around the world.

Of particular interest are findings made recently by OSU scientists that vitamin D induces the "expression" of cathelicidin, an antimicrobial peptide gene. This explains in part how it helps serve as the first line of defense in your immune response against minor wounds, cuts, and both bacterial and viral infections. Experts believe advances in the use of cathelicidin may form the basis for new therapies.

Once believed to be related primarily to bone health and rickets - a disease caused by chronic deficiency of vitamin D - it's now understood that optimal levels of this nutrient influence much more than that.

"Vitamin D insufficiency and deficiency is a world-wide, public health problem in both developed and developing nations," the new report concluded. "Nearly one billion people world-wide are deficient."

Vitamin D can be obtained from the diet, often through supplemented foods such as milk, but those sources are rarely adequate, experts say. Most people get the bulk of this fat-soluble vitamin from the UV-B radiation in sun exposure, which naturally causes the skin to produce it. However, people with dark skin, infants and almost anyone living north of about 40 degrees latitude - which is a huge portion of the U.S. population and most of Europe - are often deficient after months of inadequate winter sunshine.

Among the values and observations about vitamin D that are outlined in the new report:

- Low levels of circulating vitamin D are associated with increased risk and mortality from cancer.


- Vitamin D plays an important role in activating the immune system, fostering the "innate" immune response and controlling over-reaction of adaptive immunity, and as such may help control autoimmune diseases such as multiple sclerosis, psoriasis and rheumatoid arthritis.


- Cathelicidin can profoundly boost the innate immune system, and could form the basis for new therapies to combat pathogenic infections.


- The regulation of cathelicidin by vitamin D, a unique biological pathway for the function of vitamin D that could help explain its multiple roles in proper immune function, is so important that it's only known to exist in two groups of animals - humans and non-human primates - and has been conserved in them through millions of years of evolution.


- Vitamin D deficiency is a risk factor for tuberculosis, was historically used to treat it, and analogs of it may provide the basis for new therapeutic approaches not only to that disease but also HIV infection.


- Epidemiological studies show a link between vitamin D deficiency and increased rates of respiratory infection and influenza, and it has been hypothesized that flu epidemics may be the result of vitamin D deficiency.


- Higher levels of a protein linked to vitamin D have been associated with reduced infections and longer survival of dialysis patients.


- Vitamin D has important roles in reducing inflammation, blood pressure and helping to protect against heart disease



There is still much to explore about the mechanisms of action of vitamin D, the potential use of synthetic analogs of it in new therapies, and its role in fighting infection, Gombart said. Since only primates and humans have the same biological pathways for use of vitamin D to regulate cathelicidin, studies have been constrained by the lack of appropriate animal models for research, he said. OSU scientists hope to address that by creation of a line of genetically modified mice that have some of these characteristics.

One compelling new study just done by researchers at the Intermountain Medical Center in Utah, and presented at a meeting of the American Heart Association, followed for more than a year nearly 28,000 patients ages 50 or older with no prior history of cardiovascular disease. It found that in patients with very low levels of vitamin D - compared to those with normal levels - 77 percent were more likely to die, 45 percent were more likely to develop coronary artery disease, and 78 percent were more likely to have a stroke.

Research at OSU on vitamin D and cathelicidin has been supported by the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.

Source: Adrian Gombart
Oregon State University

[vonneke]

http://vita-info.nl/2008/12/vitamine-d/

Vitamine D is een pro-hormoon dat in de huid, met behulp van zonlicht, wordt gevormd uit cholesterol. Hoe donkerder de huidskleur des te meer zonlicht nodig is. Door de lever en de nieren wordt deze vitamine D3 omgezet in het hormoon dat de lichaamsactieve vorm is van deze vitamine D ( 1,25-dihydroxy-vitamine D ).

[vonneke]

http://ajprenal.physiology.org/cgi/cont ... l/289/1/F8

Abstract

The vitamin D endocrine system plays an essential role in calcium homeostasis and bone metabolism, but research during the past two decades has revealed a diverse range of biological actions that include induction of cell differentiation, inhibition of cell growth, immunomodulation, and control of other hormonal systems.

Vitamin D itself is a prohormone that is metabolically converted to the active metabolite, 1,25-dihydroxyvitamin D [1,25(OH)2D].
This vitamin D hormone activates its cellular receptor (vitamin D receptor or VDR), which alters the transcription rates of target genes responsible for the biological responses.

This review focuses on several recent developments that extend our understanding of the complexities of vitamin D metabolism and actions: the final step in the activation of vitamin D, conversion of 25-hydroxyvitamin D to 1,25(OH)2D in renal proximal tubules, is now known to involve facilitated uptake and intracellular delivery of the precursor to 1-hydroxylase.

Emerging evidence using mice lacking the VDR and/or 1-hydroxylase indicates both 1,25(OH)2D3-dependent and -independent actions of the VDR as well as VDR-dependent and -independent actions of 1,25(OH)2D3.

Thus the vitamin D system may involve more than a single receptor and ligand.
The presence of 1-hydroxylase in many target cells indicates autocrine/paracrine functions for 1,25(OH)2D3 in the control of cell proliferation and differentiation. This local production of 1,25(OH)2D3 is dependent on circulating precursor levels, providing a potential explanation for the association of vitamin D deficiency with various cancers and autoimmune diseases.

[vonneke]

http://www.medicalnewstoday.com/articles/177496.php

Low Vitamin D Levels Linked To Poorer Lung Function In Asthmatics

Asthmatics with higher blood levels of vitamin D have better lung function than those with lower levels, according to new research from National Jewish Health, in Denver.

The findings have been published online ahead of print publication in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine

[vonneke]

http://www.medicalnewstoday.com/articles/181501.php

Low Levels Of Vitamin D Linked To Muscle Fat, Decreased Strength In Young People

There's an epidemic in progress, and it has nothing to do with the flu. A ground-breaking study published in the March 2010 Journal of Clinical Endocrinology and Metabolism found an astonishing 59 per cent of study subjects had too little Vitamin D in their blood. Nearly a quarter of the group had serious deficiencies (less than 20 ng/ml) of this important vitamin. Since Vitamin D insufficiency is linked to increased body fat, decreased muscle strength and a range of disorders, this is a serious health issue.


"Vitamin D insufficiency is a risk factor for other diseases," explains principal investigator, Dr. Richard Kremer, co-director of the Musculoskeletal Axis of the Research Institute of the MUHC. "Because it is linked to increased body fat, it may affect many different parts of the body. Abnormal levels of Vitamin D are associated with a whole spectrum of diseases, including cancer, osteoporosis and diabetes, as well as cardiovascular and autoimmune disorders."

The study by Dr. Kremer and co-investigator Dr. Vincente Gilsanz, head of musculoskeletal imaging at the Children's Hospital Los Angeles of the University of Southern California, is the first to show a clear link between Vitamin D levels and the accumulation of fat in muscle tissue - a factor in muscle strength and overall health. Scientists have known for years that Vitamin D is essential for muscle strength. Studies in the elderly have showed bedridden patients quickly gain strength when given Vitamin D.

The study results are especially surprising, because study subjects - all healthy young women living in California - could logically be expected to benefit from good diet, outdoor activities and ample exposure to sunshine - the trigger that causes the body to produce Vitamin D.

"We are not yet sure what is causing Vitamin D insufficiency in this group," says Dr. Kremer who is also Professor of Medicine at McGill University. High levels of Vitamin D could help reduce body fat. Or, fat tissues might absorb or retain Vitamin D, so that people with more fat are likely to also be Vitamin D deficient."

The results extend those of an earlier study by Dr. Kremer and Dr. Gilsanz, which linked low levels of Vitamin D to increased visceral fat in a young population. "In the present study, we found an inverse relationship between Vitamin D and muscle fat," Dr. Kremer says. "The lower the levels of Vitamin D the more fat in subjects' muscles."

While study results may inspire some people to start taking Vitamin D supplements, Dr. Kremer recommends caution. "Obviously this subject requires more study," he says. "We don't yet know whether Vitamin D supplementation would actually result in less accumulation of fat in the muscles or increase muscle strength. We need more research before we can recommend interventions. We need to take things one step at a time."

[vonneke]

http://www.medicalnewstoday.com/articles/181515.php

Vitamin D Crucial To Activating Immune Defenses

Scientists at the University of Copenhagen have discovered that Vitamin D is crucial to activating our immune defenses and that without sufficient intake of the vitamin, the killer cells of the immune system - T cells - will not be able to react to and fight off serious infections in the body.

For T cells to detect and kill foreign pathogens such as clumps of bacteria or viruses, the cells must first be 'triggered' into action and 'transform' from inactive and harmless immune cells into killer cells that are primed to seek out and destroy all traces of a foreign pathogen.

The researchers found that the T cells rely on vitamin D in order to activate and they would remain dormant, 'naïve' to the possibility of threat if vitamin D is lacking in the blood.

Chemical Reaction that Enables Activation

In order for the specialized immune cells (T cells) to protect the body from dangerous viruses or bacteria, the T cells must first be exposed to traces of the foreign pathogen. This occurs when they are presented by other immune cells in the body (known as macrophages) with suspicious 'cell fragments' or 'traces' of the pathogen. The T cells then bind to the fragment and divide and multiply into hundreds of identical cells that are all focused on the same pathogen type. The sequence of chemical changes that the T cells undergo enables them to both be 'sensitized to' and able to deliver a targeted immune response.

Professor Carsten Geisler from the Department of International Health, Immunology and Microbiology explains that "when a T cell is exposed to a foreign pathogen, it extends a signaling device or 'antenna' known as a vitamin D receptor, with which it searches for vitamin D. This means that the T cell must have vitamin D or activation of the cell will cease. If the T cells cannot find enough vitamin D in the blood, they won't even begin to mobilize."

T cells that are successfully activated transform into one of two types of immune cell. They either become killer cells that will attack and destroy all cells carrying traces of a foreign pathogen or they become helper cells that assist the immune system in acquiring "memory". The helper cells send messages to the immune system, passing on knowledge about the pathogen so that the immune system can recognize and remember it at their next encounter. T cells form part of the adaptive immune system, which means that they function by teaching the immune system to recognize and adapt to constantly changing threats

Activating and Deactivating the Immune System

For the research team, identifying the role of vitamin D in the activation of T cells has been a major breakthrough. "Scientists have known for a long time that vitamin D is important for calcium absorption and the vitamin has also been implicated in diseases such as cancer and multiple sclerosis, but what we didn't realize is how crucial vitamin D is for actually activating the immune system - which we know now. "

The discovery, the scientists believe, provides much needed information about the immune system and will help them regulate the immune response. This is important not only in fighting disease but also in dealing with anti-immune reactions of the body and the rejection of transplanted organs. Active T cells multiply at an explosive rate and can create an inflammatory environment with serious consequences for the body. After organ transplants, e.g. T cells can attack the donor organ as a "foreign invader". In autoimmune disease, hypersensitive T cells mistake fragments of the body's own cells for foreign pathogens, leading to the body launching an attack upon itself.

The research team was also able to track the biochemical sequence of the transformation of an inactive T cell to an active cell, and thus would be able to intervene at several points to modulate the immune response. Inactive or 'naïve' T cells crucially contain neither the vitamin D receptor nor a specific molecule (PLC-gamma1) that would enable the cell to deliver an antigen specific response.

The findings, continues Professor Geisler "could help us to combat infectious diseases and global epidemics. They will be of particular use when developing new vaccines, which work precisely on the basis of both training our immune systems to react and suppressing the body's natural defenses in situations where this is important - as is the case with organ transplants and autoimmune disease

Most Vitamin D is produced as a natural byproduct of the skin's exposure to sunlight. It can also be found in fish liver oil, eggs and fatty fish such as salmon, herring and mackerel or taken as a dietary supplement. No definitive studies have been carried out for the optimal daily dosage of vitamin D but as a large proportion of the population have very low concentrations of vitamin D in the blood, a number of experts recommend between 25-50mg micrograms a day.

The findings will be published in the latest edition of Nature Immunology, (Vitamin D controls T cell antigen receptor signaling and activation of human T cells ) 10.1038/ni.1851, on 07 March 1800 London Time/1300 Us Eastern Time.

[vonneke]

http://www.medicalnewstoday.com/articles/182425.php

Treating Vitamin D Deficiency Significantly Reduces Heart Disease Risk

Preventing and treating heart disease in some patients could be as simple as supplementing their diet with extra vitamin D, according to two new studies at the Intermountain Medical Center Heart Institute in Murray, Utah.

Researchers at the Intermountain Medical Center Heart Institute last fall demonstrated the link between vitamin D deficiency and increased risk for coronary artery disease. These new studies show that treating vitamin D deficiency with supplements may help to prevent or reduce a person's risk for cardiovascular disease and a host of other chronic conditions. They also establish what level of vitamin D further enhances that risk reduction.

Study findings was presented at the American College of Cardiology 59th annual scientific session in Atlanta on March 15, 2010.

"Vitamin D replacement therapy has long been associated with reducing the risk of fractures and diseases of the bone," says Dr. J. Brent Muhlestein, MD, director of cardiovascular research at the Intermountain Medical Center Heart Institute. "But our findings show that vitamin D could have far greater implications in the treatment and reduction of cardiovascular disease and other chronic conditions than we previously thought."

For the first study, researchers followed two groups of patients for an average of one year each. In the first study group, over 9,400 patients, mostly female, reported low initial vitamin D levels, and had at least one follow up exam during that time period. Researchers found that 47 percent of the patients who increased their levels of vitamin D between the two visits showed a reduced risk for cardiovascular disease.

In the second study, researchers placed over 31,000 patients into three categories based on their levels of vitamin D. The patients in each category who increased their vitamin D levels to 43 nanograms per milliliter of blood or higher had lower rates of death, diabetes, cardiovascular disease, myocardial infarction, heart failure, high blood pressure, depression, and kidney failure. Currently, a level of 30 nanograms per milliliter is considered "normal."

Heidi May, PhD, a cardiovascular clinical epidemiologist with the Intermountain Medical Center Heart Institute, and one of the study's authors, says the link between low levels of vitamin D and increased risk for a variety of diseases is significant.

"It was very important to discover that the 'normal' levels are too low. Giving physicians a higher level to look for gives them one more tool in identifying patients at-risk and offering them better treatment," says Dr. May.

Dr. Muhlestein says the results of these studies will change the way he treats his patients.

"Although randomized trials would be useful and are coming, I feel there is enough information here for me to start treatment based on these findings," he says.

"Although randomized trials would be useful and are coming, I feel there is enough information here for me to start treatment based on these findings," he says.

Treatment options in this case are simple, starting with a blood test to determine a patient's vitamin D level. If low levels are detected, supplements and/or increased exposure to sunlight may be prescribed.

Increasing vitamin D intake by 1000 to 5000 international units (IU) a day may be appropriate, depending on a patient's health and genetic risk, says Dr. Muhlestein. He says supplements are the best source of vitamin D because they are relatively inexpensive and can be found at almost any supermarket or drug store. Most supplements provide an average of 400 IU per tablet.

While exposure to 20-30 minutes of sunlight can provide up to 10,000 IU, Dr. Muhlestein says it is important to use sunscreen and avoid the hottest parts of the day in order to avoid sunburn and the harmful UV rays associated with skin cancer.

[vonneke]

http://www.medicalnewstoday.com/articles/182304.php

Vitamin D Levels Have Different Effects On Atherosclerosis In Blacks And Whites

Vitamin D is quickly becoming the "go-to" remedy for treating a wide range of illnesses, from osteoporosis to atherosclerosis. However, new evidence from a Wake Forest University School of Medicine study suggests that supplementing vitamin D in those with low levels may have different effects based on patient race and, in black individuals, the supplement could actually do harm.

The study is the first to show a positive relationship between calcified plaque in large arteries, a measure of atherosclerosis or "hardening of the arteries," and circulating vitamin D levels in black patients. It appears in the March issue of the Journal of Clinical Endocrinology and Metabolism.

"In black patients, lower levels of vitamin D may not signify deficiency to the same extent as in whites," said the study's lead investigator, Barry I. Freedman, M.D., John H. Felts III Professor and chief of the section on nephrology at the School of Medicine "We should use caution when supplementing vitamin D in black patients while we investigate if we are actually worsening calcium deposition in the arteries with treatment."

Vitamin D is widely used to treat patients with osteoporosis and/or low vitamin D levels based on a medically accepted normal range. This "normal" range is typically applied to all race groups, although it was established predominantly in whites. It is thought that as low vitamin D levels rise to the normal range with supplementation, protection from bone and heart disease (atherosclerosis) may increase, as well.

Blacks generally have lower vitamin D levels than whites, partly because their darker skin pigmentation limits the amount of the vitamin produced by sunlight. Blacks also consume fewer dairy products and ingest less dietary calcium than whites, said Freedman, an affiliate of the Maya Angelou Center for Health Equity, part of the School of Medicine. Despite these lower vitamin D levels and dietary calcium ingestion, blacks naturally experience lower rates of osteoporosis and have far less calcium in their arteries. Studies further reveal that black patients with diabetes have half the rate of heart attack as whites, when provided equal access to health care. This shows that lower levels of calcified atherosclerotic plaque in blacks are associated with a lower risk of heart disease. However, blacks in the general community have higher rates of heart attack than whites, potentially due to unequal access to medical care, Freedman said.

The research team determined the relationship between circulating vitamin D levels and arterial calcium in 340 black men and women with type 2 diabetes. Calcium can deposit in blood vessel walls forming a bone-like material called "calcified atherosclerotic plaque" and this plaque can be detected by computed tomography (CT) scans. Calcified atherosclerotic plaque is a reliable predictor of risk for heart attack and stroke. The investigators measured vitamin D levels in all study participants and then performed a CT scan to detect calcium in the heart and major arteries.

"We found that higher circulating levels of vitamin D in blacks were associated with more calcium in the artery walls," Freedman said. "This is the opposite effect of what is felt to occur in white patients and shows that the accepted "normal" range of vitamin D may be different between blacks and whites.

Many of these study patients would be placed on supplemental vitamin D by their physicians simply because their levels were felt to be in the low range." Freedman added that physicians should use caution in supplementing vitamin D levels in blacks - especially if they do not have weak bones or other reasons to take this vitamin - until the effects of supplementing vitamin D on blood vessels and heart disease are better understood.

"Doctors frequently prescribe supplemental vitamin D," Freedman said. "However, we do not know all of its effects and how they may differ between the races. The bottom line is that racial differences in calcium handling are seen and black and white patients have differing risk for bone and heart disease. We should more clearly determine the effects of supplementing vitamin D in black patients with low levels based on existing criteria and should not assume that the effects of supplementation will be the same between the races."

[vonneke]

Rheumatoid Arthritis Linked To Vitamin D Deficiency :

http://www.medicalnewstoday.com/articles/184826.php

[bamboe]

http://www.telegraph.co.uk/health/healt ... ystem.html

Vitamin D 'triggers and arms' the immune system
Vitamin D is crucial to the fending off of infections, claims new research.

By Richard Alleyne, Science Correspondent
Published: 6:00PM GMT 07 Mar 2010

The so-called sunshine vitamin, which can be obtained from food or manufactured by human skin exposed to the sun, plays a key role in boosting the immune system, researchers believe.

In particular it triggers and arms the body's T cells, the cells in the body that seek out and destroy any invading bacteria and viruses.


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Pathogenic flu 'increases risk of Parkinson's disease'Scientists at the University of Copenhagen have discovered that Vitamin D is crucial to activating our immune defences and that without sufficient intake of the vitamin, the killer cells of the immune system – T cells – will not be able to react to and fight off serious infections in the body.

For T cells to detect and kill foreign pathogens such as clumps of bacteria or viruses, the cells must first be ‘triggered’ into action and "transform" from inactive and harmless immune cells into killer cells that are primed to seek out and destroy all traces of invaders.

The researchers found that the T cells rely on vitamin D in order activate and they would remain dormant, ‘naïve’ to the possibility of threat if vitamin D is lacking in the blood.

Professor Carsten Geisler from the Department of International Health, Immunology and Microbiology, said: "When a T cell is exposed to a foreign pathogen, it extends a signalling device or ‘antenna’ known as a vitamin D receptor, with which it searches for vitamin D.

"This means that the T cell must have vitamin D or activation of the cell will cease. If the T cells cannot find enough vitamin D in the blood, they won’t even begin to mobilise. ”

The discovery, the scientists believe, provides much needed information about the immune system and will help them regulate the immune response.

This is important not only in fighting disease but also in dealing with anti-immune reactions of the body and the rejection of transplanted organs.

Active T cells multiply at an explosive rate and can create an inflammatory environment with serious consequences for the body.

After organ transplants, T cells can attack the donor organ as a ‘foreign invader’. In autoimmune diseases, like arthritis or Crohns Disease, T cells mistake fragments of the body’s own cells for foreign invaders, leading to the body launching an attack upon itself.

For the research team, identifying the role of vitamin D in the activation of T cells has been a major breakthrough.

“Scientists have known for a long time that vitamin D is important for calcium absorption and the vitamin has also been implicated in diseases such as cancer and multiple sclerosis, but what we didn’t realise is how crucial vitamin D is for actually activating the immune system – which we know now, ” said the researchers.

The findings, continues Professor Geisler, “could help us to contain infectious diseases and global epidemics.

They will be of particular use when developing new vaccines, which work precisely on the basis of both training our immune systems to react and suppressing the body’s natural defences in situations where this is important – as is the case with organ transplants and autoimmune disease.”

Most Vitamin D is produced as a natural by-product of the skin’s exposure to sunlight. It can also be found in fish liver oil, eggs and fatty fish such as salmon, herring and mackerel or taken as a dietary supplement.

The findings are published in the latest edition of Nature Immunology.