Does Vitamin C Help With Colds, The Flu, And COVID?

At the first sign of a sore throat or runny nose, it’s not uncommon for parents to reach for Emergen-C or pour a heaping glass of orange juice. People drown themselves in vitamin C when it comes to cold and flu season, hoping it will stave off the cold, flu, and COVID — or at least prevent their illness from getting too bad if they do get infected. But how much of this link between vitamin C and illness is an old wives’ tale, and how much of it is based in science? Does vitamin C helps with colds? As it turns out, it’s more of the former than the latter. But vitamin C isn’t totally useless when you get sick, studies have shown.

Does Vitamin C Help With Colds?

In the 1970’s, Linus Pauling, a double Nobel laureate and self-proclaimed champion of vitamin C, promoted megadoses of the vitamin. He recommended the equivalent of 12 to 24 oranges a day to prevent colds and some chronic diseases, such as cancer and heart disease. And on one aspect, he was right: Science does support daily intake of vitamin C because, as a water-soluble vitamin, the body doesn’t store it easily. But high doses of vitamin C don’t prevent disease.

No studies have conclusively shown vitamin C has any benefit in preventing illness, especially the common cold. It does play an important role in boosting the immune system, but most people in the United States are not vitamin C-deficient, so taking extra vitamin C doesn’t necessarily boost the immune system, says Oladimeji Oki, M.D., a family physician at the Montefiore Medical Center and a professor of family and social medicine at Albert Einstein College of Medicine. There are some exceptions to this rule, he says. “We tend to see vitamin C deficiency in people with little access to food or severe poverty, people who are institutionalized and not eating well, or those who have an aversion to most if not all foods and vegetables, such as some children with autism.”

That’s not to say that vitamin C is useless when it comes to cold and flu season. One study, which included 463 students ranging from ages 18 to 32, investigated the effects of a megadose of vitamin C in preventing and relieving cold and flu symptoms. Students in the control group who developed symptoms were given pain relievers and decongestants, and those in the experimental group who got sick were treated with hourly doses of 1,000 milligrams of vitamin C for the first six hours, then three times daily thereafter. Although vitamin C didn’t prevent participants from getting sick, those who took the supplement before and after getting sick reported an 85% decrease in flu and cold symptoms.

One study showed that a supplemental dose of 1,000 to 2,000 milligrams per day can shorten the duration of a cold by 18% in children. Another study showed an additional dose of 6,000 to 8,000 milligrams can reduce the duration of a cold in adults. However, other studies have not found the same effect, so experts can’t be sure whether people who regularly take vitamin C supplements have shorter colds. What is clear is that taking extra vitamin C doesn’t reduce the risk of catching the common cold.

Does Vitamin C Help With COVID?

Vitamin C does not prevent or cure COVID. Clinical trials are exploring whether vitamin C, in combination with other treatments, could help COVID patients, but no studies have found that it provides a significant benefit in the treatment of COVID. However, having a robust immune system is a good defense against COVID, and daily intake of vitamin C will help in this regard — although, again, most people do get enough vitamin C.

How Much Vitamin C Should You Take Per Day When Sick?

The Food and Nutrition Board recommends that men aged 19 and older intake at least 90 milligrams of vitamin C per day, and women should get at least 75 milligrams. Most people actually get more than that.

But be careful about getting too much vitamin C. The maximum tolerated dose is 2000 milligrams per day for adults and 400 to 1800 milligrams for children aged 1-18 years. Exceeding this amount can cause gastrointestinal distress and diarrhea.

If you’re trying to get more vitamin C in your diet, citrus actually isn’t your best bet. Although it is an excellent source, bell peppers are actually the best. One cup of chopped raw red bell pepper contains 200 to 300 milligrams of vitamin C, about 100 milligrams more than a cup of orange juice. Other good sources of vitamin C include broccoli, brussels sprouts, kiwi, strawberries, papaya, pineapple, and cantaloupe.

Vitamin C When Sick: The Bottom Line

Although there’s no definitive proof that taking vitamin C can prevent illness, it may shorten symptoms of the common cold and flu. A healthy and balanced diet will provide the correct amount of vitamin C and, coupled with exercise, will do a better job of improving immunity than focusing on megadosing vitamin C during cold and flu season.