With all the H1N1 discourse and debate, the nation's focus is definitely on flu season. With so much attention given to the prevention and treatment of the flu, it seems that the other big winter illness - the common cold - is getting less attention. While the common cold is typically the gentler sickness of the two - it still allows many to go to work and school, for example, while the flu usually lays people up for a week or more - it is still a drain on us, both as individuals, and as a wider population. To protect ourselves from getting a cold or the flu, physical barriers usually rule the day: hand-washing, not sharing cups or water bottles, or staying out of busy public places altogether are strategies that we hear about over and over again.
But what about your diet? Is there anything you can take that will make you less likely to get the cold? And once you're in the clutches of one, is there anything that can make a cold's duration shorter or its symptoms less severe? While there are numerous purported cold remedies on the market, here are the highlights of a few popular nutritional supplements and their possible benefits - or lack thereof - in preventing the common cold.
When it comes to cold prevention, who doesn't think about popping some vitamin C? After decades of recommendations based largely around the prevention of scurvy, vitamin C made its way into our collective consciousness with two-time Nobel laureate Linus Pauling's assertions that mega-dosing was a pathway to good health. Now, many of us don't think twice about popping several thousand milligrams at a time, and there is a widely held belief that taking vitamin C at the onset of a cold will hold it at bay.
But what does the research say? In 2007, the Cochrane Database of Systematic Reviews - basically, the granddaddy of evidence-based reviews on medical research - published an updated review of vitamin C and the common cold, and found that, in a nutshell, yes, vitamin C regularly can reduce the length one suffers from a cold - by 8% in adults and 14% in children, as long as it is taken regularly. But when taken after the onset of symptoms, there was no effect on the length or severity. In other words, megadosing on vitamin C after you feel your first sniffle doesn't seem to do much.
Although the general population may not benefit from taking vitamin C for a cold, there is some evidence that athletes training at a high level (marathon runners, for example), and those exposed to extreme cold temperatures can benefit from popping a few pills.
VITAMIN D
The sunshine vitamin plays a role in immune system function, and at least according to early evidence, it might help to prevent respiratory tract infections. In fact, a study published in the February edition of the journal Archives of Internal Medicine found that individuals with a lower circulating level of vitamin D had a higher likelihood of developing a respiratory tract infection.
On the other hand, a more recent study, published in the October issue of Epidemiology and Infection, found that subjects given 2000 IU of vitamin D over a 12 week period were no less likely to develop a respiratory tract infection. Since there is very limited research on the role vitamin D plays in the development of the common cold, the bottom line is that we simply don't yet know enough to be able to do anything but speculate. Having said that, since so many Canadians are vitamin D deficient by late fall or early winter - the time when cold and flu season hits full stride - taking a vitamin D supplement probably isn't a bad idea, even if it is for other health benefits than cold prevention.
GARLIC
Long used by numerous cultures for taste and health, garlic's antimicrobial and antiviral properties has earned it a reputation as a classic cold-fighter. But does the evidence agree? According to a Cochrane review published earlier this year, researchers found that there is insufficient evidence to suggest that garlic should be used to either prevent or treat the common cold. Bear in mind, however, that the issue was not so much that garlic isn't useful, but rather that there haven't been enough well-controlled trials to allow a clear conclusion to be drawn, one way or the other.
In fact, in one double-blinded trial, subjects given garlic pills containing 180 mg of allicin (the active compound in garlic) for 12 weeks developed only a third as many colds as those given a placebo (dummy pill) for the same amount of time. Since double-blinded, placebo-controlled trials are considered the gold standard for proof, the results would certainly suggest that garlic has a role to play, at least in cold prevention, but more good trials are needed.
ZINC
A known immune system modulator, there is some research to suggest that zinc can be used to manage respiratory tract infections, pneumonia, and the common cold. While there is some indication that zinc supplements might be most beneficial for children and the elderly - in other words, those with weakened or compromised immune systems - the data is inconsistent.
As for the benefits of using zinc lozenges to treat the common cold, the reviewers at Cochrane deemed the data inconclusive. Yes, there are several well-controlled trials, and some have demonstrated that zinc lozenges can, in fact, reduce the duration or the severity of the common cold, others have shown no effect. The difference could be the result of the type of zinc used and its bioavailability (the ability of the body to uptake and use a particular form of a nutrient), but the possibility of bias was also raised.
No comments:
Post a Comment