Prevent The Flu With Vitamin D

Vitamin D is likely your best bet to prevent the flu. Let me explain. Research has shown that supplementing with Vitamin D reduced the flu dramatically. In fact doctors now believe that the reason the flu is seasonal (in the winter time) is that our Vitamin D levels drop during the winter due to lowered levels of sunlight.

Did you ever wonder why there is a flu season? That is, “Why do flu viruses cause a problem only in the winter time?” Our friends in public health would say that in the winter time (in northern climates) humans tend to be closer together in the winter. We’re huddled together inside because its cold outside. Being in closer proximity allows the flu, which is communicated primarily by touch and sneeze, to travel from one person to another more readily. It makes sense that being in closer proximity would increase flu incidence a bit.

But does it explain the fact that the flu is seasonal? Researchers have found another more viable explanation which involves vitamin D. It is only recently that the medical community has come to appreciate the prime importance of vitamin D in our health. My first exposure to Vitamin D in high school biology (or was it nutrition?) was that vitamin D deficiency caused rickets. When vitamin D was deficient calcium could not be absorbed and the bones got weak. We now know that Vitamin D does much more than promote calcium absorption. Vitamin D has been found to impact the expression of over 200 genes in the human body. Among other things Vitamin D enhances your immunity to infection. It does so by stimulating the production of a substance called cathelicidin in white cells. Cathelicidin is anti-microbial. It helps the white cells to kill invaders, be they a virus or bacteria.

Okay, so what if Vitamin D helps stimulate our immunity? What’s that got to do with the flu?

That still doesn’t explain anything about the flu happening in the winter time. But yes it does, and here’s why. Vitamin D is synthesized when sunlight hits our skin. In northern climates there is less sunlight during winter (November through February in most places). There is also a corresponding drop in the population’s vitamin D levels during the winter time. According to John Cannell, M.D. roughly 70% of the US population has Vitamin D levels that are too low (below 35 ng/ml). Lack of sunlight in the winter time further aggravates this deficiency. How important is sunlight for Vitamin D production? A young white adult will manufacture 20,000 IU of Vitamin D within minutes of full body exposure to sunlight. And again, in the winter time we have less sun light, and consequently our body makes less Vitamin D.

But this still doesn’t prove the Vitamin D – flu virus connection, does it? Here’s where the researchers come in with what they believe is the beginning of the proof of a Vitamin D-seasonal flu connection. John Aloia and Melissa Li-ng published their research in an article entitled “Epidemic Influenza and Vitamin D” in the journal Epidemiology and Infection (October, 2007). The authors studied 208 women over the course of three years. The women were randomly divided into two groups of 104 each. One group received 800 IU of Vitamin D and the other received none (a placebo). The groups were followed for two years to see how many women got the flu. The group taking Vitamin D had 8 cases of the flu. The group not taking Vitamin D had 26 cases, or more than 3 times the number. During the final year of the experiment the women who had been taking 800 IU of Vitamin D had their daily dose increased to 2000 IU. The third year there was only once case of the flu in the group receiving the Vitamin D.

Another group of researchers published their findings in an article that appeared in the medical journal Nature Medicine in April, 2006. The article was entitled “Fighting Infections With Vitamin D”. The authors begin by noting that in 1903 Niels Finsen received the Nobel Prize for discovering that sunlight cured tuberculosis. This sunlight therapy cured and/or improved 95% of cases. The reason was unknown at the time. Now we know that Vitamin D stimulates the immune systems production of anti-microbial substances. The authors go on to say that our current recommendations for Vitamin D intake are based on what is required for bone health. Research findings suggest that the optimum Vitamin D intake to insure a strong and healthy immune system is more than that.

How much Vitamin D should you take for a strong immune system?

There are two answers. The first is that ideally you should have your Vitamin D levels tested. The ideal range for Vitamin D (calcidiol) is 35 to 50 ng/ml. Many commercial labs report a “normal” Vitamin D level as being anywhere between 8 to 72 ng/ml. So rather than getting a “normal” back from the lab, you need to see that the number is between 35-50 ng/ml. If you don’t want to test your Vitamin D level, and you do not get a lot of sun exposure, take 800-2000 IU of cholecalciferol (Vitamin D3) per day. Vitamin D3 is found only in animal sources. Vitamin D2 (ergocalciferol) is available from plants. Be careful that your Vitamin D supplement does not contain too much Vitamin A. For instance cod liver oil contains 1,200 IU of Vitamin D and 14,000 IU of Vitamin A per tablespoon. Taking a 2000 IU dose of cod liver oil per day gives you too much Vitamin A, and Vitamin A can be toxic.

What about Vitamin D toxicity? What is the danger?

Vitamin D toxicity is not common. The best way to assure against toxicity is to have your Vitamin D levels checked periodically. Joh Cannell, M.D. of The Vitamin D Council reports that it would take 100,000 capsules of 1,000 IU Vitamin D to approach the lethal dose of Vitamin D in a 150 pound man. Research has demonstrated that taking 4,000 IU of Vitamin D for up to six months has no ill effects. If you make a concerted effort to get sunshine exposure, you can drop your intake of supplemental Vitamin D to 800 IU daily.

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Dr. Harlan Mittag is a chiropractor in St. Louis Park and Minneapolis, MN and owner of Mittag Holistic Chiropractic. He is a chiropractor, nutritionist and acupuncturist who specializes in the treatment of natural pain and natural pain remedies. A graduate of Stanford University and Northwestern College of Chiropractic, he has had a clinical practice in Minneapolis, Minnesota for the past 25 years.

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