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Does Vitamin C Really Help Ward Off a Cold?

A vitamin C zealot sets out to find the truth

I’m a vitamin C truther. In fact, as of writing this, I’m drinking my second cup of Emergen-C of the day and it’s not yet noon. Why? Because I’m sick. I have a cold and the mucus in my sinuses is so pressurized I can feel it wanting to burst out of my pores.

Like most people, I hate being sick, which is why I love vitamin C and why I believe in its wondrous power as a cure-all. How could I not? My parents and grandparents have been peddling vitamin-C propaganda my entire life. But am I wasting my time?

“Given that vitamin C differs from a placebo, it’s evident that vitamin C does have some effect,” says Harri Hemilä, a doctor at the University of Helsinki who’s researched the effects of Vitamin C on the common cold. “There are two studies that indicate that taking 200 milligrams of vitamin C a day might shorten the duration of colds by some 20 percent. But then we have the question of whether 20 percent is a small or large effect, and that question is a subjective issue.”

As for how the vitamin C works, Hemilä explains that it acts as an antioxidant, which helps protect cells from damage caused by free radicals.

Still, Hemilä says that, the possibility of catching a cold because you have low levels of vitamin C isn’t even a real concern in the West. “In Western countries, your body is never so low in Vitamin C that it matters for infections,” he explains, which will no doubt be a relief for anyone worrying about scurvy.

With that in mind, is it possible that I’m overdosing on vitamin C, considering each pack of Emergen-C is packing 1,000 milligrams? “For adults, the recommended dietary reference intake for vitamin C is 200 to 500 milligrams a day, and the upper limit is 2,000 milligrams a day,” says Hemilä.


So what happens to the rest of it? According to Hemilä, since the human body can only absorb up to 200 milligrams of Vitamin C per day, the rest just comes out in your urine. “But I wouldn’t worry about the higher doses you’ve been taking,” he says. “For those with extra oxidative stress during a cold or flu, I often recommend an extra 1,000 milligrams. Vitamin C is water soluble, and the body can easily eliminate it.”

Still, by that standard, the only thing I’m really preventing by taking so much vitamin C is my own chances of saving enough money for an early retirement.