Can Vitamin D Replace Flu Shots?

The Wall Street Journal reports:

Vitamin D, long known for its beneficial effect on bones, is increasingly being studied to see if it helps prevent colds and flus. Based on early research results, some doctors are recommending high doses to help stave off the upper respiratory infections, with some even speculating it could be a substitute to the annual flu shot. But while it's well established that vitamin D boosts the immune system, many scientists say so far there's insufficient evidence that taking it will help keep a cold or flu away.

Until recently, scientists have blamed the higher prevalence of flu cases during winter to the tendency of humans to congregate inside or the low humidity of cold weather, which makes viruses survive in the air longer. Increasingly, scientists are exploring another possible explanation: During the wintertime, we are outside less, resulting in lower vitamin D absorption from the sun.

An article well worth your time.