In the largest trial done so far, vitamin D failed to lower the risk of colds or other respiratory infections even though earlier evidence had suggested that people with lower vitamin D levels have a higher risk of colds.
The study, conducted in New Zealand randomly assigned 322 adults to get either a high dose of vitamin D or a placebo. After 18 months, and two winter seasons, the probability of upper respiratory infections was no lower in the people who took vitamin D than those who took the placebo. While it ‘s important to take vitamin D to protect your bones (check with your doctor on the dosage right for you) it will unlikely help you fight off colds this winter season…..Nutrition Action December 2012