Why Might Vitamin C Supplements be Beneficial in Treating the Common Cold?

Are vitamin C supplements beneficial in treating the common cold?

Vitamin C is not really a silver bullet for the common cold even though it has been recommended since the 1970s. Over a billion cases of the common cold occur in the United States every year, but despite the widespread use of vitamin C and it being studied for many years, there is only a little proof that it actually has any effect preventing or treating the common cold. So, are vitamin C supplements beneficial in treating the common cold?

However, it does have potential benefits against the general misery, stuffiness, and sore throat that come along with the cold but has not been proven to reduce the frequency, duration, or severity. The vitamin's role in the production of interferon, a protein that can keep viruses from multiplying, appears to be ­important.

What is vitamin C?

Vitamin C, L-ascorbic acid, is an important vitamin and antioxidant that is essential for the growth, repair, and maintenance of muscles, bones, blood vessels, the skin, cartilage, and gums. It also produces tissue, speeds wound healing, regulates blood clotting, and helps disarm free radicals that damage cells. It also helps the body absorb iron and assists in the formation of collagen. It is water-soluble, meaning it dissolves in water. Since it is not stored in the body, it must be replaced daily.

What contains vitamin C?

It is found naturally in many foods such as tomatoes, citrus fruits, vegetables, and broccoli. It is also available in a dietary supplement, cough drops, juices, tea, or other forms.

More about studies and trials

The common cold is the most extensively studied infection with regard to the effects of vitamin C. An unresolved controversy, however, is how much vitamin C to take. The majority of controlled trials have used the modest dosage of only 1 gram per day. Pooling published studies, it seems that there has been a highly significant difference between the groups taking vitamin C and the groups taking a placebo, which indicates a possible biological effect. However, the maximal effects of vitamin C and the optimal doses on the common cold are still unknown.

In a statistical analysis, Dr. Harri Hemilä from the University of Helsinki, Finland, published the findings of two trials regarding the effects of vitamin C doses on the common cold's duration.

The first trial administered three grams a day to two groups, six grams a day to a third group, and a placebo to the fourth group. Compared to the placebo group, the six grams a day shortened colds by 17 percent, twice as much as the three grams a day dose.

The second trial administered four grams a day and eight grams a day and a placebo to different groups, but only on the first day of the cold. Compared to the placebo group, the eight grams a day shortened the colds by 19 percent, which is twice as much as the four grams a day.

Dr. Hemilä concluded that it would be worthwhile for patients to test whether a therapeutic eight grams a day of vitamin C is beneficial for them. It may be that even higher doses of over 15 grams a day may lead to even greater duration reductions. Vitamin C must be started as soon as possible after the onset of the cold symptoms to be most effective.

Meanwhile, researchers at Beloit College in Wisconsin studied the urine samples of 50 healthy adults to establish their vitamin C levels. Their findings were that a high dose of 500 mg of vitamin C taken every 12 hours, the equivalent of 16 oranges a day, seemed to be the optimal dose for a regular health regime.

Take vitamin C while healthy

Researchers have stated that taking the vitamin supplements while you are still healthy could likely lessen the symptoms' severity and allow you to get better faster if you do get a cold because of the antihistamine effect of the high-dose supplement.

The researchers also pointed out that most healthy adults get a cold only two or three times a year, so taking a large dose of vitamin C every day on a regular basis to slightly shorten the duration of only a few colds may not be the best approach. The study also showed that waiting to take vitamin C until the cold symptoms appear does not lessen the severity or duration.

Is it safe to take vitamin C?

Generally, it is safe to take along with food. Also, taking the supplement in the recommended daily allowance of 90 mg for men and 75 mg for women is also safe. However, be aware that high doses, especially greater than 2000 milligrams each day for adults, may possibly cause nausea, diarrhea, or kidney stones. A buffered supplement is easier on those who find the vitamin's acidity on their stomachs upsetting.

Why Might Vitamin C Supplements be Beneficial in Treating the Common Cold?

Most researchers have concluded that a routine mega-dose is not rationally justified for the general population. However, evidence suggests that it could be justified in people exposed to cold environments or brief periods of severe physical exercise. Consult with your health-care provider for specific information relative to your own individual needs.

Last Reviewed:
August 16, 2017
Last Updated:
October 20, 2017
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