Vitamin C for Colds—Does It Actually Work?

Overdoses of this antioxidant can be harmful, but in the right amount it can help shorten colds and decrease severity
By Kris Gunnars, authoritynutrition.com

The common cold is the most frequent infectious disease in humans, and the average person gets one several times per 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 about cold prevention using megadoses of vitamin C, 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 studies had proved this to be true.

But in the following decades, multiple randomized controlled studies examined whether the vitamin had any effect on the common cold.

The results have been fairly disappointing.

An analysis of 29 studies including 11,306 participants concluded that supplementing with 200 mg or more of vitamin C did not reduce the risk of catching a cold (1).

However, regular vitamin C supplements had several benefits, including:

  • Reduced cold severity: They reduced the symptoms of a cold, making it less severe.
  • Reduced cold duration: Supplements decreased recovery time by 8% in adults and 14% in children, on average.

A supplemental dose of 1–2 grams was enough to shorten the duration of a cold by 18% in children, on average (1).

Other studies in adults have found 6–8 grams per day to be effective (2).

Vitamin C appears to have even stronger effects in people who are under intense physical stress. In marathon runners and skiers, vitamin C almost halved the duration of the common cold (1).

SUMMARY: Although vitamin C supplements have no effect on the risk of catching a cold, they appear to reduce its severity and duration.How Does Vitamin C Reduce the Severity of Colds?

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 vitamin C 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’s less known that vitamin C is also highly concentrated in immune cells and quickly depleted during an infection (3).

In fact, a vitamin C deficiency significantly weakens the immune system and increases the risk of infections (4).

For this reason, getting enough vitamin C during an infection is a good idea.

SUMMARYVitamin C is essential for the proper functioning of immune cells. It is depleted during infections, so a vitamin C deficiency may increase their risk.

Other Nutrients and Foods That May Help

There is no cure for the common cold.

However, some foods and nutrients can help the body recover. In the past, people have used various foods to reduce their symptoms.

Few of these are scientifically proven to work, but some are backed 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 spice contains some antimicrobial compounds that may help fight respiratory infections. Read this detailed article for more information (6).

SUMMARY: Several other nutrients and foods may help you recover from a cold or even reduce the risk of catching one. These include flavonoids and garlic.

While taking supplements may be necessary to reach the high vitamin C intake required to improve colds, make sure not to go overboard.

That’s because too much vitamin C has some adverse side effects.

To meet your basic nutrient requirements, whole foods are generally a better idea. Good examples of healthy foods that are high in vitamin C include oranges, kale, and red bell peppers.

 Kris Gunnars is a nutrition researcher with a Bachelor’s degree in medicine. An evidence-based nutrition article from our experts at Authority Nutrition, his article was originally published on Healthline.