Vitamin C: Does it actually help you avoid getting sick?

by Jenna Finley

We’ve all heard someone say at some point: “I think I’m getting sick so I’ll just take a ton of vitamin C and it’ll be fine.” The idea that a dose of vitamin C will keep you from getting the flu (or at least stop the illness from lingering) is one of the most common home remedies nowadays, and the reason vitamin C tablets fly off the shelves right around the beginning of cold and flu season. However, does this home remedy actually help?

Short answer: we’re not sure.

Vitamin C began to be thought of as an important guardian of health in the 1970s when prominent doctors began recommending daily doses as a way for people to lead longer, healthier lives. But it wasn’t until the 1990s that vitamin C began to be more widely touted as a common cold prevention method. Drugs containing vitamin C began popping up on shelves claiming to be common cold cures, the most prominent of which was called Airborne. Since its release, the drug has been the subject of multiple lawsuits over the unsubstantiated claims made involving the “cold busting” power of vitamin C and yet has still inspired dozens of new ‘cold preventing’ vitamin C supplements.

As far as research goes, very little support has been found for the idea that taking vitamin C will help prevent an illness, at least for the general public. If you’re an extremely active person who takes a dose of 250-1000mg of vitamin C every single day, then you could reduce your cold incidence by half! Great news for Olympic athletes and marathon runners, but for the rest of us, washing our hands regularly would be more helpful.

The possibility of shortening the length of a cold and reducing its symptoms is where the research gets more interesting, though not in the way you might expect. The research findings are also a lot more conflicted in this area. While some studies suggest that vitamin C can reduce symptoms as much as 85%, others say the supplementation makes no difference. The most popular and cited study says that vitamin C can make a difference, but only if a 200mg vitamin C supplement is taken every single day -  not just the days you’re feeling sick or the days leading up to a cold. I don’t think a lot of us can say that we meet that condition, but even if we did, the benefits aren’t too exciting. On average, this regime leads to only one less day of illness.

Taking a massive amount of vitamin C at once (megadosing) is another common method people use in the hopes that they’ll finally be free of that persistent cold. While some research seems to agree with this treatment, there is yet another caveat. The dose necessary to have a chance at relieving your illness would need to be as high as 8000mg/day, which can cause a whole host of problems. In the end, the 1000mg tablets your roommate is eating like candy around exam season might be doing them more harm than good, as too much vitamin C can make you a lot sicker, resulting in symptoms like vomiting, abdominal pain, and diarrhea.
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Therefore, we can’t conclusively say that vitamin C supplementation helps, but we do know that it can hurt. Most nutritionists recommend getting your daily needed vitamin C from your meals and forgoing a supplement all together. Doses over 400mg are excreted from the body and can result in you (literally) flushing your money down the toilet.
At the end of the day, if you’re still convinced a few vitamin C tablets will help you stave off the dreaded common cold for another day, go ahead and take them, but be careful. No one wants to suffer any more than they have to during exam season.