Vitamin C for Preventing and Treating the Common Cold

the Public Library of Science Medicin ^ | June 2005 | Robert M. Douglas*, Harri Hemilä

[MRMEAN]

Vitamin C for Preventing and Treating the Common Cold

Robert M. Douglas^*, Harri Hemilä

Robert M. Douglas is at the National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australia. Harri Hemilä is at the Department of Public Health, University of Helsinki, Finland.

Competing Interests: RMD was an organising author of one of the papers considered in the review. HH declares that he has no competing interests.

Published: June 28, 2005

DOI: 10.1371/journal.pmed.0020168

Copyright: © 2005 Douglas and Hemilä. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Citation: Douglas RM, Hemilä H (2005) Vitamin C for Preventing and Treating the Common Cold. PLoS Med 2(6): e168

*To whom correspondence should be addressed. E-mail: bobdouglas@netspeed.com.au

---

The role of vitamin C in the prevention and treatment of the common cold has been a subject of controversy for at least 60 years. Public interest in the subject, stimulated originally by the vigorous advocacy of Nobel laureate Linus Pauling during the 1970s [1], continues to be high. We have recently updated the Cochrane Review [2] on this topic (Text S1), incorporating 55 comparative studies that have been carried out over a period of 65 years.

The Updated Review

We sought to discover whether vitamin C in doses of 200 mg or more daily (Figure 1) reduces the incidence, duration, or severity of the common cold when used either as continuous prophylaxis or after the onset of cold symptoms. Criteria for inclusion were placebo-controlled trials to prevent or treat the common cold using oral doses of vitamin C of 200 mg/day or more. Literature from 1940 to 2004 was methodically screened.

Figure 1. 500-mg Vitamin C Tablets and Paprikas

Vitamin C was identified in the 1930s by Albert Szent-Györgyi, who received his Nobel Prize partly for this work. He found that paprika is a particularly rich source of the vitamin, which made it possible to produce kilograms of it for research purposes ([1963] Annu Rev Biochem 32: 1–14). Nowadays, the most convenient way to increase vitamin C intake is by way of 500-mg tablets, but further research is needed to explore the conditions in which supplementation may be beneficial.

An overview of the results of the three meta-analyses is shown in Table 1. Incidence was not altered in the subgroup of 23 community studies where prophylactic doses as high as 2 g daily were used. But a subgroup of six studies of marathon runners, skiers, and soldiers exposed to significant cold and/or physical stress experienced, on average, 50% reduction in common cold incidence.

Table 1. Results of the Three Meta-Analyses

Duration of cold episodes that occurred during prophylaxis was significantly reduced in both children and adults. For children this represented an average reduction of 14% in symptom days, while in adults the reduction was 8%.

For the seven trials that evaluated the therapeutic impact of vitamin C used at the onset of symptoms (all in adults), benefits were not observed for duration of episodes, although one of the large trials recorded a statistically significant reduction in the duration of colds among participants administered a single vitamin C dose of 8 g on the day of symptom onset [3].

Implications of the Review

The lack of effect of prophylactic vitamin C supplementation on the incidence of common cold in normal populations throws doubt on the utility of this wide practice. The clinical significance of the minor reduction in duration of common cold episodes experienced during prophylaxis is questionable, although the consistency of these findings points to a genuine biological effect.

In special circumstances, where people used prophylaxis prior to extreme physical exertion and/or exposure to significant cold stress, the collective evidence indicates that vitamin C supplementation may have a considerable beneficial effect; it was the results of one of these six trials, with schoolchildren in a skiing school [4], that particularly impressed Pauling [1]. However, great caution should be exercised in generalizing from this finding, which is based mainly on marathon runners.

No benefits have been observed from therapeutic use of doses totalling 10 g that was divided for the first three days of illness. The equivocal findings of the large study, which used 8 g only on the day of onset of respiratory symptoms [3], are tantalising and deserve further assessment.

None of the therapeutic trials carried out so far has examined the effect of vitamin C on children, even though the prophylaxis trials have shown substantially greater effect on episode duration in children.

Study quality for the trials included in these three meta-analyses was variable, but sensitivity analysis, where we excluded studies from the analysis that were less adequately blinded or randomized, did not change the general conclusions of the Cochrane Review.

Future work on this topic should explore the value of high dose therapy—in particular, in children—and the mechanisms underlying the observed prophylaxis benefits in those exposed to substantial physical and/or cold stress.

Supporting Information

Text S1. Updated Cochrane Review

Douglas RM, Hemilä H, D'Souza R, Chalker EB, Treacy B (2004) Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 4: CD000980.pub2.

Date of most recent substantive amendment: 10 August 2004.

This data supplement can be freely accessed on the PLoS Medicine Web site, but it is not published under the Creative Commons Attribution License.

Copyright © 2004 The Cochrane Collaboration. Published by John Wiley and Sons. All rights reserved.

(1.3 MB PDF).

[MRMEAN]

Linus Pauling's very high dose recommendations for taking Vitimin C were not supported by research done by his collegue Arthur Robinson, Pauling then suppressed that research.

[goodnesswins]

Yeah...but, Vitamin C makes a great laxative (at certain doses).

[GSlob]

Everyone knows that common cold is mightily helped by alcohol imbibing. For those more academically minded, Aristotle in his Problemata (book 1, problem 50) recommended sexual excess as beneficial for the diseases caused by phlegm.

[Kirkwood]

Many years ago in the 1970s I met privately with Linus Pauling and questioned him about his Vitamin C research. He refused to discuss it, and kept changing the subject to other things like the world running out of oil by the late 1980s.

[paulat]

Your "suppressed" link doesn't work for me. Any hints?

[c-b 1]

I was under the impression that Linus Pauling was black balled, and his research suppressed, by his colleagues.

[Nachum]

I don't know about the research, but in my experience vitamin c has been effective in helping me fight bronchial infection and colds.

[LibWhacker]

Linus Pauling's very high dose recommendations for taking Vitimin C were not supported by research done by his collegue Arthur Robinson . . .

Heck, it wasn't even supported by Pauling's own work. Analyzing his data was a homework assignment in a categorical data analysis course I took in college. Turns out he used the wrong statistical test.

[cincinnati65]

All I can offer is my own anecdotal evidence. When I first feel the onset of a cold, I mega-dose Vitamin C, washing down the tablets with orange juice. There have been many instances where I woke up the next morning with no cold symptoms at all.

[reformedcrat]

"All I can offer is my own anecdotal evidence. When I first feel the onset of a cold, I mega-dose Vitamin C, washing down the tablets with orange juice. There have been many instances where I woke up the next morning with no cold symptoms at all."

Yep. Same here. I'm convinced it works...from my own unscientific study of one (me.)

--Marty

[FreeKeys]

All I can offer is my own anecdotal evidence. When I first feel the onset of a cold, I mega-dose Vitamin C, washing down the tablets with orange juice. There have been many instances where I woke up the next morning with no cold symptoms at all.

Me too. In fact I used to get swollen lymph glands in my neck, and only 4,000-5,000mg of Vitamin C every 12 hours would make them go away, usually in 36 hours. NOTHING else worked. At the onset of a cold I take a megadose of C, chelated minerals, lots of garlic, and proprietary concoctions called Conco, Congaplex and Botanamune which has echinacea and goldenseal, among other things. Knocks it right out.

[CurlyDave]

I choose to believe Linus Pauling. Thge 200 mg dose in the articles is a joke. I take 2 grams--10 times as much per day. Colds are few & far between.

Remember, Linus Pauling has one more Nobel prize than any of his critics.

[Capriole]

I used to get colds constantly, and for me, this was a big deal because they would cause exacerbations of my asthma, and the initial cold virus infection would frequently turn into secondary bronchial bacterial infections. I'd be sick, and sometimes on doctor-prescribed steroids, for months. When I started taking Vitamin C prophylactically, at a dosage of 1 g per day, the colds have almost gone away. I get about one per year now and it's brief and mild, with no secondary infection setting in. I have more physical resilience than I had fifteen years ago. Anecdotal? Sure. But it works for me and my kids; we're the only people I care about.

[southernnorthcarolina]

GSlob: "Everyone knows that common cold is mightily helped by alcohol imbibing.

cincinnati65: "All I can offer is my own anecdotal evidence. When I first feel the onset of a cold, I mega-dose Vitamin C, washing down the tablets with orange juice. There have been many instances where I woke up the next morning with no cold symptoms at all."

I subscribe to both of those theories.

A Screwdriver (vodka and orange juice on the rocks); a Gin Blossom (gin and orange juice, chilled and straight up); a Mimosa (Champagne, or preferably a non-French substitute, and orange juice); or a Salty Dog (vodka and grapefruit juice, either on the rocks or chilled and straight up, with a salted rim) are among the "remedies" I have experimented with. Fresh-squeezed citrus if possible!

Does it work? Hell, I dunno. But it makes colds more bearable. Hmmm, do I feel a case of the sniffles coming on?

[television is just wrong]

You cannot just start off taking massive doses. You should start by taking 500 - 1000 mg per day and work up gradually to what is optimum. It is really not necessary to take much more than 5,000 mg. per day.

[FreeKeys]

Thge 200 mg dose in the articles is a joke.

Oh, that's right. ALL other mammals produce their own vitamin C right in their bodies, but somehow our common ancestors lost their ability to do so. In fact, a 100-lb. goat makes 14grams (14 THOUSAND milligrams) a day, so 200mg is a LUDICROUS joke.

[qam1]

A Screwdriver (vodka and orange juice on the rocks);

In order to be truely effective you have to add rum to it. And not Bacardi or Captain Morgan, Cheap rum only (Castillo seems to work best).

So rum, vodka & orange juice

3 of those will take any cold or flu out. Hell, I was knocking on death's door when I was infected with the Hanta Virus and it wasn't until I broke out of the hospital and got a pack of cigarettes and hit the bar and downed a few of these that I got cured of the dammed thing.

[reformedcrat]

"I used to get colds constantly, and for me, this was a big deal because they would cause exacerbations of my asthma, and the initial cold virus infection would frequently turn into secondary bronchial bacterial infections. I'd be sick, and sometimes on doctor-prescribed steroids, for months. When I started taking Vitamin C prophylactically, at a dosage of 1 g per day, the colds have almost gone away. I get about one per year now and it's brief and mild, with no secondary infection setting in. I have more physical resilience than I had fifteen years ago. Anecdotal? Sure. But it works for me and my kids; we're the only people I care about."

Weird. This is my story exactly! Prednisone following a cold was all that kept me out of the hospital during an after-cold asthma attack.

4 grams of C before bedtime. Every night for years now.

--Marty

p.s. It's cheapest at Costco.

[William Terrell]

Aristotle in his Problemata (book 1, problem 50) recommended sexual excess as beneficial for the diseases caused by phlegm.

Continuous prophylaxis, of course.

[GSlob]

Sorry, but the folk medicine prescription (in Moscow of 1970s) used to be: from a standard 500ml size vodka bottle (in the United States the bottles are 750ml, so take due note of this) - so, from a 500ml bottle one drinks about 350ml - straight, in the evening. One needs to take good care not to sleep on one's back afterward, for some people were known to get suffocated by their own drunken vomit. So, the next morning the patient wakes up and grabs the bottle in which there should be about 150ml still left. This amount would be used to drink down the hangover - and the yesterday's cold sufferer is like new!

[lewislynn]

Around 1965/66, I had a yellow streak running up my arm from my elbow to my armpit. Following my friend's dad's advice (a pediatrician) I cleared up a case of blood poisoning with mega doses of Vitamin-C.

[GSlob]

While continuous might be difficult, frequent should be OK.

[MRMEAN]

Your "suppressed" link doesn't work for me. Any hints?

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VITAMIN C AS A MAGIC BULLET

Since Petr Beckmann has revealed, in the July issue, the skeletons in your new editor's professional closet, we may as well get the ascorbic acid question out of the way and save a lot of unnecessary correspondence. Many AtE readers, including me, are undoubtedly consuming the stuff.

During the 1970s, 12 research papers were published that included among their authors Linus Pauling and Arthur Robinson. I was senior author of seven, Linus of three, and other scientists of two. During some of those years I was President and Research Director of the Pauling Institute.

Several other papers should have been published, but were suppressed by lawyers whom Linus rewarded with over one million dollars in legal fees. Although Linus was eventually punished by being required to make large financial payments for personal damages, much valuable research about ascorbic acid and other health subjects was never properly published.

This has been of continuing interest, because many people supplement their diet with vitamin C. Since the dosages consistent with optimum health are still unknown, there is concern about the guesses that are made in determining current nutritional recommendations.

Beginning in the 1920s, interest was aroused by laboratory work showing anti-viral effects of ascorbic acid in petri dish cultures. This led to empirical observations by some physicians including especially Fredrick Klenner and by many individuals with curiosity about nutrition.

By the mid 1950s, a general attitude had come to prevail in the health food subculture concerning vitamin C. 500 mg per day was considered a reasonable maintenance dose for good health, several grams per day was considered sensible when ill, and some people like Klenner advocated very large (even injected) doses for serious illnesses. Maintenance doses recommended were frequently as high as about 3000 mg per day. Much uncontrolled anecdotal experimentation and very little rigorous scientific work was the basis for these recommendations.

In the late 1960s, word of this reached Pauling, who was aging and beginning to have increased concern about his own health. He initially adopted the popular 3000 mg per day dosage.

Whether vitamin C rejuvenated Linus's tissues is unknown, but it certainly didn't hurt his hunger for notoriety. In succession over the next decade, Pauling and retainers claimed that vitamin C was a cure for the common cold, for mental illness, for cancer, and for AIDS. In order to seize the initiative from the health food gurus, Pauling gradually raised his recommended dosage to about 20,000 mg per day. Exemplary was Pauling's claim, unretracted to the present, that "75% of all cancer can be prevented and cured by vitamin C alone." Although Pauling avoided direct experimental tests ("I don't need to do experiments. People believe me, because of who I am.") experiments were done.

Not only did these experiments fail to confirm the exaggerated claims, but concerns arose over the safety of very high chronic dosages. Vitamin C oxidation products were shown to degrade proteins and DNA in physiological solutions and to damage cultures of human cells. Incidence and severity of cancer in mice actually rose in some dose ranges, although they fell in others. Several scientists who were unlucky enough to obtain such results suffered vicious personal and professional attacks by Pauling.

For many years, good research on vitamin C (a potentially valuable substance in the maintenance of good health) came almost to a halt as attention focused on the test of Pauling's increasingly wild claims. It was not a cure for cancer, but did it help perhaps a little? This had been suggested long before Pauling, but an experimental test was delayed by his publicity campaign.

Today much of this hoopla has subsided and biochemists are getting along with the job of gradually understanding this important substance. Many people take 500 to 3000 mg of vitamin C each day as a nutritional supplement just as the health food gurus of the 1950s were recommending. These doses are probably safe. The experiments on ascorbic acid oxidation products suggest that doses much higher than this should be avoided in healthy people.

Edward Teller told me several years ago that even he takes vitamin C "so that there will be at least one thing that Linus and I agree about." Ironically, the contrived argument that Pauling used so effectively against Teller in their famous debates about atomic testing would bury vitamin C were it used in a similar debate today.

Pauling argued that the harmful effects of high radiation doses should be linearly extrapolated to zero. This led to predictions of damaging health effects from the low amounts of atmospheric radiation being produced by atomic tests. Today, as AtE readers are well aware, it is known that these low doses are actually of positive biological value.

Any extrapolation of the biological effects of vitamin C oxidation products at high doses into the low dose range would certainly be enough for an FDA ban of this substance—which is actually required for life in small amounts.

Pauling is, however, running a personal experiment. He has been taking massive doses of vitamin C for over 20 years and is now 92 years old. He is still alive although afflicted with two sorts of cancer. If vitamin C has prolonged his life, then it has given him the opportunity of watching the collapse of the political empires of international socialism to which he sold his political soul. Petr Beckmann's joy has been Pauling's pain.

I personally hope Linus makes it to 100. And if he does, I may change my recommendation to no more than 3,000 mg per day until the age of 70. After that, mainline the stuff! (Don't do it.) One warning—prolonged supplementation of vitamin C creates a biological dependency. Withdrawal from this addiction should be gradual over several weeks to avoid harmful scorbutic effects.

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•	Petr Beckman
•	SAGA OF THE VANISHING TREES
•	VITAMIN C AS A MAGIC BULLET
•	NUCLEAR ECONOMICS
•	SAFETY FIRST
•	LE CHATELIER AND THE EARTH
•	STARK RAVING MAD
•	GOOD READING

Vol. 21, No. 1

Newsletter: Access to Energy Newsletter Archive
Volume: Issues
Issue/No.: Vol. 21, No. 1

Date: September 01, 1993 04:42 PM
Title: Petr Beckman

Copyright © 2004 - Access to Energy Newsletter Archive
All rights reserved.

[paulat]

Thanks, Mr. Mean!

[southernnorthcarolina]

4 grams of C before bedtime. Every night for years now.

Whew. That's a lot of C. I trust you take it in tablet form as opposed to orange juice.

Your post moved me to do a little research. Vitamin C content of OJ varies wildly depending on the type of juice (fresh vs. bottled, frozen concentrate, etc.), and depending upon its freshness (values fall off sharply upon exposure to air), but 50 mg per 8 oz. seems about the average. So 80 cups (= 640 oz. = 5 gallons) would get you there.

[William Terrell]

But definitly excess. . .

[SoIA-79]

I knew someone that tried to OD on Vitimin C once. He wasn't exactly Gods gift to common sense.

As for it's effectiveness, it seems to help me but that might be the Placebo effect.

[SoIA-79]

I find tequila shooters, cheap whisky and a pack of Reds will cure anything that ails you.

[JoeGar]

I used to work for a major pharmaceutical company. In the 1980s, they conducted research into Vitamin C as a cure for the common cold. Their studies were inclusive. However, the white pulp beneath the outer skin of an orange was "shown to have biology" -- whatever that means.

[Mjaye]

My cure of choice is Zicam, available in the supermarket/drugstore. It has knocked out all colds but one, a lollapalooza cold that at least went away in relatively few days as opposed to the weeks everyone else had it. I take it the minute I have symptoms, and every three hours or so thereafter until symptoms are gone. Many people I know have begun using it and swear by it. I can't take lots of Vitamin C, so had to look elsewhere.

[GSlob]

Most definitely. Aristotle was writing of "sexual excess" [verbatim]. Enjoy the cure.

[goodnesswins]

YES...I know....

[FreeKeys]

I can't take lots of Vitamin C

Neither could my sister, but I sent her a bottle of Calcium Ascorbate caps ("buffered" C you might say) which is NOT acidic, and it works for her. I think the brand was Solaray, but there are others out there.