How To Prevent The Flu And Common Cold: Are Vitamin D Supplements The Key?

As the temperatures drop and the sniffles start, the quest to find some method to prevent the annual onslaught of the common cold or flu becomes increasingly desperate every winter. But now researchers in the United Kingdom believe they may have struck upon an effective method to stave off the debilitating illnesses for millions each year.

A new analysis from a team at Queen Mary University of London, published Wednesday in the British Medical Journal, claims vitamin D supplements can help protect against respiratory infections – which include everything from a sniffle to the flu and pneumonia.

The study collected data from 25 randomized controlled trials of 11,321 people. It concluded that one person would avoid an acute respiratory tract infection for every 33 who took vitamin D supplements. That would make it more effective than the flu vaccine, which only prevents one infection for every 40 people taking it. It would also mean 3.25 million avoiding the cold or flu in the U.K. every year.

The study found that vitamin D supplements were more effective when taken daily or weekly, rather than in large monthly does, and in those who were already deficient.

Vitamin D can be made naturally in the skin while out in the sun, but those in the UK and in much of the United States and beyond struggle to get enough sun in the dark, overcast winter months. It may be one reason why there is a rise in incidents of the common cold and flu in winter.

In the U.S., vitamin D is already added to milk, however, a 2010 study found that 42 percent of American adults were deficient in the vitamin, which is also needed to strengthen bones. And researchers have argued in favor of greater fortification of foods.

“Vitamin D fortification of foods provides a steady, low-level intake of vitamin D that has virtually eliminated profound vitamin D deficiency in several countries,” one of the researchers, Adrian Martineau, said. "By demonstrating this new benefit of vitamin D, our study strengthens the case for introducing food fortification to improve vitamin D levels in countries such as the U.K. where profound vitamin D deficiency is common."