If the current strain of H1N1 swine flu is like flu strains of the past, it likely will mysteriously subside in the coming weeks. That is because in temperate areas such as North America, flu largely is a fall and winter problem. A couple of theories have tried to explain that seasonality, but an intriguing new idea has emerged in recent years:

Levels of flu-fighting vitamin D reach their lowest point in the winter when ultraviolet light disappears. Vitamin D, which is made in large amounts in the skin when exposed to solar radiation, is a hormone that regulates hundreds of genes. Some of those involve the body's innate immunity and its defenses against viruses, especially those affecting the respiratory system. The idea is that if people increased their levels of vitamin D, it might help ward off outbreaks of flu (and other illness). Research suggests that vitamin D stimulates immune cells to produce anti-microbial substances that fight and help control the replication of viruses in the body. “What vitamin D really does is play a sentinel role,” said Michael Holick, a professor of medicine, physiology and biophysics at Boston University School of Medicine. First, it is used by immune cells to fight the virus. Then, it helps temper the overall immune response and limit inflammation. Studies continue to find that large numbers of people in the U.S. Have deficient or less than optimal levels of vitamin D in their blood. In February, researchers reported a link between vitamin D levels in the blood and upper respiratory infections in a group of nearly 19,000 people ages 12 and older. Those with deficient vitamin D levels were 55% more likely to have contracted a recent cold or upper respiratory infection than those with an adequate level. The researchers, whose study was published in the Archives of Internal Medicine, notes that the current recommendation for vitamin D supplementation, between 200 and 600 International Units a day, is unlikely to produce optimal levels in the US population. Many vitamin D researchers now say that adults should be taking up to 2,000 IU a day during the fall and winter, and that most children should take up to 1,000 IU. The M'lis Company is proud to introduce Vitamin D in an easily-absorbed liquid gel form to our quality line of nutritional supplements.