Does Vitamin D prevent H1N1

Living in sunny Thailand, I noticed that there is no "winter flu season" like we have in northern countries. How could that be? Are the people of tropical countries getting something that those of us in living in the north lack?

In a paper,  J. J. Cannell explains how vitamin D intake -- obtainable either by way of sunshine or dietary supplement -- explains 14 observations about influenza:

1. Why the flu predictably occurs in the months following the winter solstice, when vitamin D levels are at their lowest,

2. Why it disappears in the months following the summer solstice,

3. Why influenza is more common in the tropics during the rainy season,

4. Why the cold and rainy weather associated with El Nino Southern Oscillation (ENSO), which drives people indoors and lowers vitamin D blood levels, is associated with influenza,

5. Why the incidence of influenza is inversely correlated with outdoor temperatures,

6. Why children exposed to sunlight are less likely to get colds,

7. Why cod liver oil (which contains vitamin D) reduces the incidence of viral respiratory infections,

8. Why Russian scientists found that vitamin D-producing UVB lamps reduced colds and flu in schoolchildren and factory workers,

9. Why Russian scientists found that volunteers, deliberately infected with a weakened flu virus - first in the summer and then again in the winter - show significantly different clinical courses in the different seasons,

10. Why the elderly who live in countries with high vitamin D consumption, like Norway, are less likely to die in the winter,

11. Why children with vitamin D deficiency and rickets suffer from frequent respiratory infections,

12. Why an observant physician (Rehman), who gave high doses of vitamin D to children who were constantly sick from colds and the flu, found the treated children were suddenly free from infection,

13. Why the elderly are so much more likely to die from heart attacks in the winter rather than in the summer,

14. Why African Americans, with their low vitamin D blood levels, are more likely to die from influenza and pneumonia than Whites are.

The whole article is worth reading.   A relatively safe and possibly effective alternative getting a flu shot this winter is to take 4,000 MG of Vitamin D daily.   That's what I'm doing.

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How much Vitamin D should you take?

Science Daily reports:

Treating Vitamin D Deficiency

In the absence of clinical guidelines, the authors outline specific recommendations for restoring and maintaining optimal vitamin D levels in CV patients. These patients should initially be treated with 50,000 IU of vitamin D2 or D3 once weekly for 8 to 12 weeks. Maintenance therapy should be continued using one of the following strategies:

* 50,000 IU vitamin D2 or D3every 2 weeks;
* 1,000 to 2,000 IU vitamin D3 daily;
* Sunlight exposure for 10 minutes for Caucasian patients (longer for people with increased skin pigmentation) between the hours of 10 a.m. to 3 p.m.

Vitamin D supplements appear to be safe. In rare cases, vitamin D toxicity (causing high calcium levels and kidney stones) is possible, but only when taking in excess of 20,000 units a day.

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Vitamin D prevents heart disease and diabetes

SD reports:

A growing body of evidence links low 25-hydroxyvitamin D levels to common CVD risk factors such as hypertension, obesity and diabetes, as well as major cardiovascular events including stroke and congestive heart failure. . . .

It is estimated that up to half of U.S. adults and 30 percent of children and teenagers have vitamin D deficiency.

"We are outside less than we used to be, and older adults and people who are overweight or obese are less efficient at making vitamin D in response to sunlight," said Dr. O'Keefe. "A little bit of sunshine is a good thing, but the use of sunscreen to guard against skin cancer is important if you plan to be outside for more than 15 to 30 of intense sunlight exposure."

Vitamin D can also be consumed through supplements and food intake. Natural food sources of vitamin D include salmon, sardines, cod liver oil, and vitamin D-fortified foods including milk and some cereals.

Personally, I think it's a better idea to cover yourself in clothing than in sunscreen (after you get your dose of sun for the day).

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Vitamin D deficiency and the flu

The flu season is associated with the time of the year with the sunshine. So a new theory holds that a lack of vitamin D might be associated with incidence of the flue. Here's the abstract of a recent journal paper:*

The epidemiology of influenza swarms with incongruities, incongruities exhaustively detailed by the late British epidemiologist, Edgar Hope-Simpson. He was the first to propose a parsimonious theory explaining why influenza is, as Gregg said, "seemingly unmindful of traditional infectious disease behavioral patterns." Recent discoveries indicate vitamin D upregulates the endogenous antibiotics of innate immunity and suggest that the incongruities explored by Hope-Simpson may be secondary to the epidemiology of vitamin D deficiency. We identify – and attempt to explain – nine influenza conundrums: (1) Why is influenza both seasonal and ubiquitous and where is the virus between epidemics? (2) Why are the epidemics so explosive? (3) Why do they end so abruptly? (4) What explains the frequent coincidental timing of epidemics in countries of similar latitude? (5) Why is the serial interval obscure? (6) Why is the secondary attack rate so low? (7) Why did epidemics in previous ages spread so rapidly, despite the lack of modern transport? (8) Why does experimental inoculation of seronegative humans fail to cause illness in all the volunteers? (9) Why has influenza mortality of the aged not declined as their vaccination rates increased? We review recent discoveries about vitamin D's effects on innate immunity, human studies attempting sick-to-well transmission, naturalistic reports of human transmission, studies of serial interval, secondary attack rates, and relevant animal studies. We hypothesize that two factors explain the nine conundrums: vitamin D's seasonal and population effects on innate immunity, and the presence of a subpopulation of "good infectors." If true, our revision of Edgar Hope-Simpson's theory has profound implications for the prevention of influenza.

It should be an easy theory to test.
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* John J Cannell et al. On the epidemiology of influenza. Virology Journal 2008, 5:29. Hat-tip Mercola.

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