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11-26-2006, 01:55 PM | #2 (permalink) |
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Rep Power: 103 | Re: Vitamin D and the flu Less sun, more sneezing Theory suggests that a shortage of vitamin D triggers outbreaks of flu By Michael Stroh Sun Reporter Originally published November 26, 2006 As the annual flu season looms, some scientists have this question on their minds: Why now? For more than a century, physicians have recognized that influenza sweeps the Northern Hemisphere during the winter months, typically peaking here between late December and March. Over the years they've floated numerous theories to explain the seasonal flu spike - blaming everything from the flood of frigid air to the wintertime tendency of people to huddle indoors. Yet these explanations "remain astonishingly superficial and full of inconsistencies," says Dr. Scott Dowell, director of the Global Disease Protection Program at the Centers for Disease Control and Prevention in Atlanta. Now Dowell and other researchers are focusing on a provocative new hypothesis that blames annual flu epidemics on something most people don't get enough of this time of year: sunshine. In a paper scheduled for publication next month in the journal Epidemiology and Infection, a Harvard University-led team proposes that a vitamin D deficiency caused by inadequate winter sun exposure may predispose people to infection. If this theory proves correct, it would not only solve a long-standing mystery, but could also have major public health consequences. Influenza kills an average 36,000 people in the U.S. each winter, mostly the very old and very young. If scientists could pinpoint the secret behind its seasonal recurrence and somehow alter it, "the potential impact would be far greater than the current influenza vaccine," says Dowell. Hippocrates, the Greek physician widely regarded as the father of medicine, was the first to recognize that certain diseases ebb and flow with the calendar. "Whoever wishes to investigate medicine properly," he wrote around 400 B.C., "should ... consider the seasons of the year." Epidemiologists, however, have found that this is easier said than done. "You look at the environment around you and say, 'What's the difference between winter and summer?'" says Dr. David Fisman of the Ontario Provincial Public Health Laboratory in Canada. "There are so many things that are seasonal, it's really hard to tease them apart." One obvious answer is that it's colder in winter. And for as long as parents have bundled up their babies, there's been an unshakable belief that catching a chill makes a person more susceptible to cold or flu. Cold flunks tests Since World War II, scientists have devised numerous teeth-chattering tests of this stubborn wives' tale, dunking volunteers in cold baths or confining them to refrigerated meat lockers while squirting virus-spiked mucus up their noses. "All attempts at demonstrating some relationship between cold exposure and susceptibility to infection have proved negative," Ron Eccles, director of the Common Cold Centre at Cardiff University in Wales, concluded in a recent published review of such studies. Experiments on the influenza virus have hinted that the flu bug is more stable in the cool, dry air of winter. But that doesn't solve the mystery, says Fisman, whose summary of efforts to understand seasonal influenza is scheduled for publication next year in the Annual Review of Public Health. One reason: Influenza surveillance efforts in Southeast Asia and other steamy tropical locales reveal that flu is not only common there but also exhibits seasonal patterns akin to those in colder climates. "If you go back to the hypothesis about cold temperature and flu, it doesn't hold for the tropics," says epidemiologist Cecile Viboud of the National Institutes of Health's Fogarty International Center in Bethesda. Then there's the crowding theory. Because scientists think that the flu spreads only from person to person, most have assumed that the disease ravages in winter because people are cooped up in close quarters.
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11-26-2006, 01:56 PM | #3 (permalink) |
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Rep Power: 103 | Re: Vitamin D and the flu But even Sir Christopher Andrewes, the British virologist who co-discovered the influenza virus in 1933, once observed, "I have always had my doubts about this." Andrewes, who died in 1988, argued that the winter crowding explanation defies common sense, since office and factory workers are stuck indoors year-round. And summertime flu epidemics remain rare despite the prevalence of cruise ships, airplanes, and subways packed with international travelers, other skeptics of the theory note. "There are plenty of things that don't fit," says the CDC's Dowell. The latest theory to generate a buzz centers on sunlight. In 1981, a British general practitioner named R. Edgar Hope-Simpson published the first paper documenting a link between influenza epidemics in the northern hemisphere and the winter solstice. The solstice - which arrives on Dec. 21 this year - is commonly identified with the start of winter and is the shortest day of the year. Hope-Simpson, who had no formal training in epidemiology, realized that influenza infections tended to jump just before and after the solstice. Solar radiation, he surmised, triggered some sort of "seasonal stimulus" that affected the flu virus, its human host or both. Although he had no idea what that seasonal stimulus was, Hope-Simpson believed that solving the mystery "would provide the key to understanding most of the influenza problems confronting us." "His work was basically ignored," says Dr. John Cannell, a psychiatrist at the Atascadero State Hospital in California. In their forthcoming paper in Epidemiology and Infection, Cannell and colleagues from Harvard University, the National Institutes of Health and Boston University propose that Hope-Simpson's seasonal stimulus could be vitamin D. The tip-off, says Cannell, came in April 2005, when an outbreak of influenza swept through Atascadero, a maximum-security facility for the criminally insane 200 miles south of San Francisco. "The ward below me got it, then the ward to my right, to my left and the one across the hall," he recalls. Cannell's 32 patients, however, were spared. As far as he could tell, there was only one glaring difference between his patients and those who came down with flu: Cannell's patients were taking high daily doses of vitamin D. Manufactured by the skin in response to solar ultraviolet B radiation (UVB), vitamin D is the only vitamin made naturally in the body. On sunny days, a fair-skinned person can crank out the equivalent of 20,000 international units (IU) of the vitamin in 15 minutes, says Cannell. One cup of fortified milk, by contrast, contains fewer than 100 IU. But vitamin D production plummets during winter because people spend less time outdoors and because UVB radiation has a harder time penetrating the atmosphere in that season, especially at middle to high latitudes. As a result, health experts in recent years have warned that many Americans may not be getting as much vitamin D as they need. One ominous sign: a recent resurgence in cases of rickets, a bone disorder caused by a lack of the vitamin. In their new paper, which draws together strands from more than seven decades of vitamin and flu research, Cannell and his colleagues argue that vitamin D stimulates production of a natural infection-fighting substance in the body called cathelicidin. Although cathelicidin has yet to be studied directly on influenza, recent research has shown that it attacks a variety of fungi, viruses, and bacteria - including the bug that causes tuberculosis, researchers reported last March in Science.
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11-26-2006, 01:57 PM | #4 (permalink) |
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Rep Power: 103 | Re: Vitamin D and the flu There's also indirect evidence of the sun's role in seasonal flu, Cannell and his colleagues argue. In the late 1970s, Soviet scientists inoculated nearly 835 young men in St. Petersburg with a weakened form of the influenza virus during different The men, they discovered, were eight times more likely to develop fever and other signs of flu infection in winter than in summer. Repeating the experiment in another city yielded similar results. And what of the sun-drenched tropics? Cannell and his colleagues point to a scattering of studies showing vitamin D deficiencies even in Hong Kong and other equatorial spots. Another important clue: A 2003 review of tropical influenza infections found the virus strikes mainly during the rainy season, presumably a time of reduced sun exposure. Maybe yes, maybe no Some researchers find the Vitamin D theory tantalizing. "It's a wonderful story, and I think there's considerable substance behind it," says immunologist Dr. Michael A. Zasloff, a professor at Georgetown University. Others, however, wonder whether this is just another vitamin fad - just as vitamin C was once promoted by double Nobel laureate Linus Pauling as a cure for the common cold. "They have manipulated the literature (some of it very bad literature) to prove their points," Dr. James Cherry, a pediatric infectious disease specialist at UCLA's David Geffen School of Medicine, wrote in an e-mail. However, "The hypothesis should be easy to prove or disprove with a controlled, blinded study," he added. Vitamin D isn't the only substance being kicked around as a seasonal stimulus candidate. The CDC's Scott Dowell favors melatonin, a naturally occurring hormone whose production is tied to the daily light-dark cycle. Preliminary research suggests that the hormone might help regulate the body's immune response. "I don't know where it's going to lead," he concedes. Cannell, meanwhile, says he takes 5,000 IU of vitamin D during the winter months, more than twice the maximum daily recommended dose. He says he rarely gets sick anymore. michael.stroh@baltsun.com
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11-26-2006, 02:12 PM | #5 (permalink) |
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Rep Power: 43 | Re: Vitamin D and the flu Me too! I used to have colds throughout the season, but not now anymore! Hooray for Vitamin D.
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11-26-2006, 07:33 PM | #6 (permalink) |
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Rep Power: 35 | Re: Vitamin D and the flu Dear Readers: Michael Stroh, the science writer for the Baltimore Sun, wrote a very good article this morning about the Vitamin D and Epidemic Influenza paper. Dr. Scott Dowell, an infectious disease expert at the CDC, is quoted by Mr. Stroh as saying, if the theory is true, "the potential impact (of vitamin D) would be far greater than the current influenza vaccine." http://www.baltimoresun.com/news/health/bal-te.flu26nov26,0,3590649.story?coll=bal-nationworld-headlines On a sour note, a Professor James Cherry of UCLA said we "manipulated the literature" and used "bad" literature to prove our points. I don't know Professor Cherry, but he has insulted me, the co-authors, and the editor of Epidemiology and Infection. A quick internet search shows that there is a Professor James Cherry at UCLA who has had substantial financial ties to the vaccine industry for the last 20 years. If Professor Cherry read the conclusion of the recent Science News article, he may be aware that his financial well-being is at risk here. In the conclusion of the Science News article, Professor Michael Zasloff was quoted as saying the payoff of vitamin D, might "be amazing. Imagine being able to block the spread of epidemic flu with appropriate doses of this vitamin." Perhaps Professor Cherry is imagining exactly that, and what it might mean to his net worth? http://www.sciencenews.org/articles/20061111/bob9.asp If Professor Zasloff and Dr. Dowell are right, vitamin D may have a role in preventing more infections than just influenza. As some of you know, a paper will soon be published in Epidemiology and Infection looking at the association of Respiratory Syncytial Virus (the most common cause of pneumonia in infants and young children) with vitamin D producing UVB surface radiation. Invasive pneumococcal, meningococcal, and streptococcal disease (all of which cause horrendous disease) might be next as all three bacteria are susceptible to antimicrobial peptides and all three diseases are highly seasonal. If this is shown to be true, Professor Cherry's income from the vaccine industry is certainly at risk. I fear Professor Cherry or others with ties to the vaccine or antibiotic industry will rapidly orchestrate a paper showing two things: one, vitamin D does not help prevent infections, and two, vitamin D is toxic and very dangerous. Perhaps science is not as corruptible as I fear, I hope so. I do hope Professor Cherry has the nerve to send a letter-to-the-editor of Epidemiology and Infection, showing how we "manipulated bad literature" to prove out points. That would give us the opportunity of producing some of the data we left out for space reasons. John Jacob Cannell, MD The Vitamin D Council 9100 San Gregorio Road Atascadero, CA 93422 |
11-27-2006, 02:25 AM | #8 (permalink) |
I love Derf!! Join Date: Mar 17 2006 Location: France
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Rep Power: 43 | Re: Vitamin D and the flu There you have it!
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