We all dread it, and we do everything we can to avoid it – but the cough & cold season is just a month or two away. Are there any vitamins we can take to prevent it?

Vitamin C is usually the vitamin that jumps to mind in conjunction with this answer, but a recent study in the Archives of Internal Medicine considered whether vitamin D may actually be where it’s at.


Dr. A. Ginde and colleagues conducted an analysis based on US population data, comparing the association between vitamin D levels and a recent history of upper respiratory tract infection. They found that the lower the vitamin D levels, the higher the likelihood of having had a recent cough or cold. This association was even stronger in people with asthma or lung disease from smoking (emphysema).
Why did they think to look at Vitamin D? Recent evidence suggests that vitamin D plays an important role in immunity, and previous smaller studies had also suggested a relationship between lower vitamin D levels and risk of cough & cold. Vitamin D is a hotbed of research these days, as studies have shown that higher vitamin D levels are not only beneficial in terms of bone health, but are also associated with a lower risk of multiple sclerosis, type 1 diabetes, and possibly cancer.
Dr. Ginde’s results must be taken with a grain of salt, however, because association does not necessarily mean causality. In other words, just because lower vitamin D levels were seen in people with higher rates of coughs and colds, does not mean that the lower vitamin D was the reason for the susceptibility to infection. There may be other factors playing in here – for example, a person who takes better care of themselves may be in better general health (therefore less infections), and in keeping with good habits, are more likely to take vitamin D supplements regularly (though the study does take several of these potential ‘confounders’ into consideration). Randomized controlled clinical trials need to be done to explore this relationship further.
As for our old friend, vitamin C: Overall, the evidence does not actually support that it decreases the risk or the severity of colds, though it may decrease the duration of colds slightly.
While the jury is still out on whether vitamin D prevents the common cold, there are many other important health reasons to make sure you are getting enough vitamin D – and most Canadians do not. For most adults, total vitamin D intake of 800 to 1,000 IU per day will maintain optimal vitamin D levels, and this is very rarely attained through diet alone – an additional supplement is required. Talk to your doctor about your vitamin D status and how much supplementation is right for you.