Does Vitamin C Really Help with Colds? - Life Extension Blog

In 1970, “Vitamin C and the Common Cold,” by Nobel Prize winner Linus Pauling, Ph.D., was
published. The book’s premise—that consuming high amounts of vitamin C could reduce cold severity and duration—was widely embraced by the public, despite the opposition of some scientists and physicians. Vitamin C began to replace chicken soup as the treatment du jour for colds and influenza and is still used for this purpose more than four decades later.

About Linus Pauling

Dr. Pauling, who has been ranked among the 20 top scientists in history, was one of just four individuals who received more than one Nobel Prize and the only one to have received two unshared prizes. He studied physics under such luminaries as Niels Bohr and Erwin Schrödinger, and was a close friend of Robert Oppenheimer. Francis Crick called Linus Pauling “the father of molecular biology.”

Dr. Pauling was the originator of the term “orthomolecular medicine,” meaning “right molecule,” which refers to providing the body with substances normally found there to treat disease. His endeavors in this area, and his advocacy of nutritional supplements, remain controversial. Dr. Pauling suggested that flawed genetics may be behind a number of diseases. His support of nutritional supplements extended to the use of intravenous vitamin C as a cancer therapy, a treatment that has of late been associated with positive reports.

A Historical Look at Vitamin C Research

A number of studies have resulted in positive findings for a protective effect of vitamin C against cold incidence, duration or symptoms. One early large scale trial, reported in 1972 in the Canadian Medical Association Journal, found a significantly greater number of vitamin C-treated subjects who remained free of colds throughout the course of the trial in comparison with those who received a placebo.1 Those who received vitamin C had approximately 30% fewer total days of disability compared to the placebo group, and a decrease in symptoms during the course of the trial. A subsequent trial found superiority for 8 grams vitamin C given on the first day of illness in comparison with 4 grams.2 This was followed by a randomized trial that revealed a 25% decrease in days of confinement due to illness among subjects who received vitamin C compared with a placebo over a 15 week period.3

In 1974, Pauling authored a review published in the Proceedings of the National Academy of Sciences that was critical of the U.S. Recommended Dietary Allowance (RDA) for vitamin C. 4 Emphasizing the antiviral and antibacterial activity of the vitamin, he suggested that optimum intake for humans may be as high as 5,000 mg per day and remarked that the RDA at that time was adequate only to prevent scurvy. In another review, W. W. Rosser, M.D., noted that the vitamin C level of white blood cells declines dramatically during the first day of an upper respiratory infection and remains at that level for three days; however, 6 grams of vitamin C consumed at the beginning of the infection prevents this from occurring.5 Dr. Rosser asserted that, while studies involving less than a gram of the vitamin were “unconvincing,” doses of 4-6 grams per day reduce cold symptoms.

“In 1971, Linus Pauling carried out a meta-analysis of four placebo-controlled trials and concluded that it was highly unlikely that the decrease in the ‘integrated morbidity of the common cold’ in vitamin C groups was caused by chance alone,” observed Dr. Harri Hemilä in a review published in 1996. “However, widespread conviction that the vitamin has no proven effects on the common cold still remains. Three of the most influential reviews drawing this conclusion are considered in the present article […] these three reviews are shown to contain serious inaccuracies and shortcomings, making them unreliable sources on the topic.”6

In another publication, Dr. Hemilä observed that, “Karlowski et al, found a 17% decrease in the duration of cold episodes in the group administered vitamin C (6 g/day); however, they suggested that the decrease was entirely due to the placebo effect. In this article it will be shown that the placebo effect is not a valid explanation for the results of the Karlowski study, as it is inconsistent with their results.”7

In the Journal of the American College of Nutrition, Dr Hemilä and Z. S. Herman reviewed an analysis conducted by Thomas Chalmers who  concluded there was no evidence for a beneficial effect for vitamin C in the treatment of the common cold. “Chalmers did not consider the amount of vitamin C used in the studies and included in his meta-analysis was a study in which only 0.025-0.05 grams/day of vitamin C was administered to the test subjects,” they observe. “For some studies Chalmers used values that are inconsistent with the original published results . . . The current notion that vitamin C has no effect on the common cold seems to be based in large part on a faulty review written two decades ago.”8

In 2017, Dr Hemilä reported that 148 animal studies indicated that vitamin C may prevent or decrease the symptoms of infections caused by viruses and bacteria.9 Controlled trials have uncovered a significant dose-response for up to 6 to 8 grams per day of the vitamin, suggesting a reason for an apparent lack of benefit in some studies that examined lower doses. “Given the consistent effect of vitamin C on the duration of colds, and its safety and low cost, it would be worthwhile for individual common cold patients to test whether therapeutic 8 grams/day vitamin C is beneficial for them,” he suggests. “Self-dosing of vitamin C must be started as soon as possible after the onset of common cold symptoms to be most effective." 

The Bottom Line

Is vitamin C helpful against colds? While the outcome and interpretation of studies are still in conflict in regard to whether the vitamin, when regularly supplemented in low amounts, can help prevent colds, a significant body of evidence exists in favor of an ability to decrease cold duration and symptoms when consumed in higher than average doses. Since most people’s intake of vitamin C is less than optimal, it can’t hurt to supplement with a prudent daily amount and to keep it on hand in the event cold or flu strikes you or a loved one. Zinc is a promising contender in the battle to prevent a full-blown cold from occurring during the first signs of a cold and to shorten the duration of a cold. 10


  1. Anderson TW et al. Can Med Assoc J. 1972 Sep 23;107(6):503-8.
  2. Anderson TW et al. Can Med Assoc J. 1974 Jul 6;111(1):31-6.
  3. Anderson TW et al. Can Med Assoc J. 1975 Apr 5;112(7):823-6.
  4. Pauling L. Proc Natl Acad Sci U S A. 1974 Nov;71(11):4442-6.
  5. Rosser WW. Can Fam Physician. 1974 Oct;20(10):113-7.
  6. Hemilä H. Nutrition. 1996 Nov-Dec;12(11-12):804-9.
  7. Hemilä H. J Clin Epidemiol. 1996 Oct;49(10):1079-84; discussion 1085, 1087.
  8. Hemilä H et al. J Am Coll Nutr. 1995 Apr;14(2):116-23.
  9. Hemilä H. Nutrients. 2017 Mar 29;9(4). 
  10. Hemilä H. J Royal Soc Medicine 2017 May;8(5).


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