I got a rather bad case of the common cold last week.
Runny nose, sore throat, mild fever and coughing. You know the drill.
Nothing really newsworthy about that, the common cold is the most frequent infectious disease in humans and the average person gets it several times during the year.
But it got me thinking about the old myth that high-dose vitamin C can prevent colds.
This theory was popularized around 1970 when Nobel prize winner Linus Pauling published a book about cold prevention using mega doses of vitamin C. He used up to 18,000 mg daily (the RDA is 75mg for women and 90mg for men).
At that time, there weren't really any reliable studies that proved this to be true.
Since then, this has been studied extensively.
Vitamin C is an antioxidant and necessary to produce collagen in the skin. Collagen is the most abundant protein in mammals, keeping skin and various tissues tough but flexible.
A deficiency results in a condition known as scurvy, which isn't really a problem today, as most people get enough vitamin C from foods.
However, it is less known that vitamin C is also highly concentrated in immune cells and consumed quickly during an infection ().
In the past few decades, multiple randomized controlled studies have examined whether the vitamin has any actual effect on the common cold.
The results have been fairly disappointing.
A meta-analysis that examined 29 studies including 11,306 participants revealed that supplementing with 200mg or more of vitamin C did not reduce frequency of colds ().
However, there was a tendency for vitamin C to reduce the severity and duration of colds.
Basically, if you take vitamin C, you'll get just as many colds as you did before, but they may be slightly less severe and last for a slightly shorter time period.
Of course, there are other potential benefits of vitamin C supplementation, and there's a lot of epidemiological evidence suggesting that adequate vitamin C from foods is linked to reduced risks of cardiovascular disease and cancer ().
Good examples of healthy foods that are high in vitamin C are oranges, kale and bell peppers. They are also high in various other beneficial nutrients.