For years, vitamin C has been the supplement of choice for battling the common cold. Now new research suggests another vitamin may be far more effective at warding off the season’s sniffles and sneezes.

In a survey of almost 19,000 Americans who participated in the Third National Health and Nutrition Examination Survey, researchers found that those with the lowest blood levels of vitamin D were 40 percent more likely to report having suffered through a bout of cold or flu than those with the highest amounts. The association was particularly strong among people with a history of asthma or serious lung conditions, such as emphysema. Asthma patients with the least vitamin D were five times more likely to have caught a respiratory bug.

Although not the first study to link vitamin D deficiency to colds and other respiratory infections, this is by far the largest. Other studies have suggested that colds may be more common in the winter because vitamin D levels are at their lowest at that time of year (the body produces D in response to sunlight exposure). Although researchers don’t know exactly why the vitamin appears to protect against respiratory infections, there’s evidence that vitamin D may help arm the immune system.

“The findings of our study support an important role for vitamin D in prevention of common respiratory infections, such as colds and the flu,” said Adit Ginde, MD, a researcher at the University of Colorado Denver Division of Emergency Medicine and lead author of the report, which appeared this week in the Annals of Internal Medicine.

While Ginde acknowledged that it’s too early to make definitive recommendations based on the new findings, he pointed out that “many Americans also need more vitamin D for its bone and general health benefits.” The new report offers one more very good reason for topping up your vitamin D reserves–especially now, toward the end of winter, when they are likely to be at the lowest ebb.

© 2009 PDQhealth

Tags: cold, flu, respiratory infections, vitamin D