Why Do We Get Sick in Winter?
With the approach of autumn, we welcome that slight chill in the air after the relentless heat of the summer. We look forward to the brilliant colors of the changing leaves, the final harvest of the fruit trees and digging out our favorite sweater. Cooler temperatures and shortening days also signal the start of flu season and the time to prepare is now.
Exposure usually occurs in one of two ways: either through hand to mouth inoculation or by droplets inhaled through our nasal passages. While we don't have much control over the air we breathe, we can control, to a large extent, what we touch. Think about your average work day. What things do you touch on a daily basis? A more important question is what do you touch that is shared by others? How about steering wheels for drivers that share vehicles and power tools used by construction workers. In an office environment, there is the keyboard, the telephone, the water cooler, the microwave, filing cabinet handles and the list goes on and on. Yet we touch these items all year round. Why then do we tend to get sick in the winter?
A relatively new theory is that with the decreased amount of daylight we produce less vitamin D. It is well known that vitamin D in important in building strong bones, but new research is revealing that this vitamin is instrumental in maintaining a healthy immune system as well. Whereas our flu season is November to March, those living in the Southern Hemisphere get the flu from June through September which is their winter months. This is an interesting piece of anecdotal evidence.
In a 2006 study published by a UCLA research team, vitamin D was able to kill bacteria responsible for tuberculosis. The researchers postulated that human differences in the ability to produce vitamin D may make certain individuals vulnerable to microbial infections. According to Dr. Julian Whitaker, a well-respected physician, increasing vitamin D intake during the winter months is a safe, if not proven, approach to protecting us against influenza. His recommendation is 800 to 1000 IU vitamin D for those living South of the parallel that runs through Philadelphia, Denver and Reno and up to 2000 IU for northerners. A recent study in the American Journal of Clinical Nutrition(September, 2007) concluded,"The widespread use of vitamin D supplements (1000 IU per day) has been advised as a simple way to improve many aspects of public health."
There are two forms of vitamin D: D2 (ergocalciferol), which does not appear naturally in humans, and D3 (cholecalciferol), the form made in the body. If you choose to supplement, make sure you get the D3 form.
For those of us who cannot jet off to the tropics during the winter months, vitamin D just may give us the edge at escaping the dreaded influenza.