Research suggests that seasonal deficiency of vitamin D could be linked to flu outbreaks in North America and other temperate areas.
Flu is largely seasonal in temperate areas, appearing and spreading rapidly during the fall and winter, subsiding through the spring and summer months, and sometimes reemerging the following autumn.Records show that flu outbreaks occur when solar radiation is at its lowest . In temperate climates flu virtually disappears during the summer months, while in tropical climates the seasonality is much less pronounced.
Researchers say the seasonal nature of flu outbreaks could possibly be linked to levels of vitamin D
D vitamin is known to stimulate the production of anti-microbial substances in immune cells, helping to halt the replication of viruses in the body. It is also known to help modulate the body’s response to respiratory viruses, preventing the overproduction of substances that can lead to dangerous and even fatal inflammation and fluid buildup in the lungs.
Though there is disagreement on vitamin D’s role as a flu fighter and the concept has yet to be substantiated by large-scale clinical tests, observational data and laboratory research support the idea that low levels of the vitamin are indeed implicated in flu outbreaks.
Among the most recent research projects to support the connection was a February, 2009 study published in the Archives of Internal Medicine, which reported a link between upper respiratory infections and deficiency of vitamin D. The study, which focused on 19,000 patients, showed that those with vitamin D deficiency were 55% more likely to have upper respiratory infections.
