Common wisdom about the common cold – what should you believe?

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TORONTO — The flu season is upon us, and more and more people are catching not only the flu, but also the common cold.

What I have found to be really interesting over the last few years is the number of so called “old wives’ tales” about colds that have actually been explored in scientific studies.

My mother always told me to dress warmly to avoid catching a cold. But when I learned that colds are caused by viruses, and not by cold air exposure, I figured that was just a myth — we don’t catch cold, we get infected with a virus.

But the twist is that a study published this year in the Proceedings of the National Academy of Sciences showed that cold weather actually reduces nasal lining cells’ immune response to the rhinovirus, allowing the virus to replicate more quickly.

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To be fair, this was a mouse study, but if we take a leap of faith, we might extend this to a theory that low outdoor temperatures turn down the immune system and truly make us more susceptible to colds.

What about that age-old warning that if you don’t get enough sleep, your immune system will get weak and you’ll get sick?

A fascinating study published this year carefully monitored people’s sleep patterns, and then gave them nasal drops containing the cold virus to see who was most likely to get infected.

Amazingly, those who slept less than 5 hours had a 45 per cent chance of getting a cold, whereas those who slept more than 7 hours had only a 17 per cent chance.

Again, this very likely has to do with the functioning of our immune system.

What about natural products for prevention and treatment of colds? Vitamin C is the big one.

A 2013 review of 29 trials with over 11,000 patients showed that vitamin C doesn’t prevent the common cold, but it does reduce the duration of cold symptoms by 8 per cent in adults and 14 per cent in kids.

Similarly, a review of 24 studies with over 4,600 patients found very marginal, if any, benefits from Echinacea for cold prevention or treatment.

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People have been talking about of zinc since the 1970s, and the most recent reviews do show that zinc can reduce the duration of cold symptoms by about a day.

The caveat is that nasal zinc sprays have caused people to lose their sense of smell, and there are other side effects.

Finally, people ask about those over-the-counter products they find in the pharmacy, such as Cold-FX, which is American Ginseng.

There have been five different studies of Cold-FX, and what we know is that when it is taken regularly as a prophylactic medication, it can reduce the duration of cold symptoms and might even prevent some colds.

But it has never been studied as a treatment for once you get a cold, which is how most people actually use it.

We are learning more and more about the truth behind some of these age old beliefs around the common cold.

But at the end of the day, the best advice is still to get your flu shot, wash your hands often, and if you do get sick, nothing works as well as a little time and a lot of rest.

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