The common cold is the most common infectious disease in humans, and the average person tends to contract it once or several times a year.
Interestingly, vitamin C has often been claimed to be an effective treatment.
Does vitamin C have any effect on the common cold?
Around 1970, Nobel Prize winner Linus Pauling popularized the theory that vitamin C helps treat colds.
He published a book on cold prevention using vitamin C megadoses, or up to 18.000 mg daily. For comparison, the RDA is 75 mg for women and 90 mg for men.
At that time, no reliable study had proven that this was true.
But in the following decades, multiple randomised controlled studies examined whether vitamin had any effect on the common cold.
The results have been quite disappointing.
An analysis of 29 studies that included 11,306 participants concluded that supplementing with 200 mg or more of vitamin C did not reduce the risk of catching a cold.
However, regular vitamin C supplements had several benefits, including:
Reducing the severity of the cold: they reduced the symptoms of a cold, which makes it less severe.
Reduced cold duration: Supplements decreased recovery time by 8% in adults and 14% in children, on average.
An additional dose of 1-2 grams was sufficient to shorten the duration of a cold by 18% in children, on average.
Other studies in adults have found that 6-8 grams per day are effective.
Vitamin C seems to have even stronger effects on people who are under intense physical stress. In marathon runners for example, vitamin C almost halved the duration of the common cold.
Although vitamin C supplements have no effect on the risk of catching a cold, they seem to reduce their severity and duration. How does vitamin C reduce the severity of colds?
Vitamin C is an antioxidant and is necessary to produce collagen in the skin.
Collagen is the most abundant protein in mammals, which keeps the skin and several hard but flexible tissues.
A deficiency of vitamin C results in a condition known as scurvy, which is not really a problem at present, as most people get enough vitamin C from food.
However, it is known less that vitamin C is also very concentrated in the immune cells and is rapidly depleted during an infection.
In fact, a vitamin C deficiency significantly weakens the immune system and increases the risk of infections.
For this reason, getting enough vitamin C during an infection is a good idea.
Vitamin C is essential for the proper functioning of immune cells. It is depleted during infections, so a vitamin C deficiency may increase your risk.
Other nutrients and foods that can help
There's no cure for the common cold. However, some foods and nutrients can help the body recover. In the past, people have used several foods to reduce their symptoms.
Few of these are scientifically proven to work, but some are backed up by evidence.
Flavonoids: These are antioxidants found in fruits and vegetables. Studies suggest that flavonoid supplements may reduce the risk of infections in the lungs, throat, and nose by 33%, on average (5).
Garlic: This common herb contains some antimicrobial compounds that can help fight respiratory infections. Read this detailed article for more information (6).
Several other nutrients and foods can help you recover from a cold or even reduce the risk of getting one. These include flavonoids and garlic.
While it may be necessary to take supplements to achieve the high intake of vitamin C needed to improve colds, be sure not to overdo it.
That's because too much vitamin C has some adverse side effects .
To meet your basic nutrient requirements, Whole foods are usually a better idea. Good examples of healthy foods with high Vitamin C content include oranges, kale, and red peppers.
Important: This article was written merely for information purposes and is not intended to replace the visit to your doctor, dietitian or specialist. If you have any concerns, consult your doctor.