Vitamin C Strikes Back in Combatting the Common Cold

Modern medicine has been unkind to Dr. Linus Pauling. Even though he is the only scientist in the world to have received two unshared Nobel Prizes, a lot of nutritionists and medical experts have criticized him for his work on vitamin C. Some have called his research on ascorbic acid doubtful at best or worthless at worst. A new review article titled “Vitamin C for the common cold and pneumonia” (online January 13, 2025) suggests that Linus Pauling might have been right all along.  The authors have done an extraordinary job reviewing the research dedicated to combatting the common cold. They went back decades to scrutinize the most relevant data and have just submitted their findings for scientific scrutiny.

Joe & Terry Discuss New Evidence About Vitamin C

Combatting the Common Cold Is NOT Easy!

Fever Reducers:

First, let’s state the obvious. Modern medicine has failed miserably at coming up with a cure for upper respiratory tract infections. Even the symptomatic treatments that have been recommended (acetaminophen or NSAIDs like ibuprofen or naproxen) to lower a fever are worthless at best and counterproductive at worst. These drugs are called “antipyretics.”

Find that hard to believe? Here is a decade-old review in the (Proceedings. Biological Sciences, Jan. 22, 2014).

“Fever is commonly attenuated with antipyretic medication as a means to treat unpleasant symptoms of infectious diseases. We highlight a potentially important negative effect of fever suppression that becomes evident at the population level: reducing fever may increase transmission of associated infections. A higher transmission rate implies that a larger proportion of the population will be infected, so widespread antipyretic drug use is likely to lead to more illness and death than would be expected in a population that was not exposed to antipyretic pharmacotherapies.”

Despite that, most of the popular products on drug store shelves contain fever reducers.

Decongestant:

What else has modern medicine offered in combatting the common cold? After fever reducers come oral decongestants like phenylephrine that clearly do not work. Nevertheless, this drug is a staple in many cold, cough and flu products. Billions have been spend on drugs with this ingredient.

The Kitchen Sink for Combatting the Common Cold:

Then we have cough suppressants, antihistamines and mucolytics. I have described these ingredients in multi-symptom cold remedies before at this link.  There isn’t any evidence that such ingredients shorten the duration of an infection. And I have doubts that they actually make people feel much better. And, as mentioned, the ubiquitous pain relievers may be counterproductive.

Despite all these negatives, we have heard very little from the medical establishment about such products. A few persistent pharmacists have voiced their concerns. Christina Jewett’s excellent article in the New York Times was titled:

“Why the F.D.A. Took So Long to Tackle a Disputed Cold Remedy

Pharmacists affiliated with the University of Florida have spent decades nudging the agency to pull a decongestant from over-the-counter medicines.”

The Times article quotes a hero of ours, Dr. Joshua Sharfstein, a former FDA heavy-weight and vice dean at the Bloomberg School of Public Health at Johns Hopkins.

Dr. Sharfstein said:

“There is no question that regulation of over-the-counter medications was broken for many years.”

And yet we have heard very little from the AMA, CDC or NIH about how ineffective our treatments have been for combatting the common cold. What we have heard, however, is how vitamin C is worthless. Let’s look at the data.

New Insights Into Combatting the Common Cold:

Let me tell you a little something regarding the individuals who have written the most recent review about Vitamin C. Are you surprised that they are not Americans? Dr. Harri Hemilä is an adjunct professor at the University of Helsinki in Finland. He has an MD in medicine, a PhD in epidemiology and a PhD in biochemistry. Elizabeth Chalker is an epidemiologist and is affiliated with the Biological Data Science Institute at the Australian National University, Canberra, Australia.

They have suggested that mainstream medicine’s (Life, Jan. 3, 2022) views:

“…on vitamin C and infections have been determined by eminence-based medicine rather than evidence-based medicine.”

In other words, the loudest shouters and the dignitaries in nutrition and modern medicine have relied upon their reputations rather than the evidence in denigrating the role of vitamin C in combatting the common cold.

A New Review Analyzes the Vitamin C Evidence:

Let’s start with animal research. According to Dr. Hemilä (Nutrients, March 29, 2017):

“After its identification, a number of studies investigated the effects of vitamin C on diverse infections. A total of 148 animal studies indicated that vitamin C may alleviate or prevent infections caused by bacteria, viruses, and protozoa.”

Hemilä and Chalker go on to note that:

“In 1971, Linus Pauling published a meta-analysis – one of the very first in medicine – in which he pooled the results of 4 placebo-controlled trials on vitamin C for the common cold and concluded that it was highly unlikely that the reported benefits could be explained by chance alone (P <0.001).”

For those unfamiliar with P values, statistical significance is usually established at a level of P<0.05. A P value of <0.001 is considered highly reliable.

The team of Hemilä and Chalker are quite clear that there is no clear evidence that vitamin C can prevent colds in the “general community.”

They go on to state, however, that:

“There is strong evidence that vitamin C can prevent colds in specific circumstances. Vitamin C halved the rate of the common cold in 5 RCTs [randomized controlled trials] with 598 participants undergoing heavy short-term physical activity such as running or skiing. The number-needed-to-treat (NNT) in these 5 trials ranged from 3 to 10.”

The Number Needed to Treat (NNT):

The “number needed to treat” is a bit complex but extremely relevant. It boils down to how many people would have to take something for one person to benefit. An NNT of 3 to 10 might not seem that great to the average person, but let me assure you that it is surprisingly good.

For comparison, the number needed to treat with statins seems less impressive. Dr. John Abramson wrote a book titled Sickening: How Big Pharma Broke American Health Care.

In it, he asked:

“Does statin therapy provide a net benefit for people at low risk of cardiovascular disease?”

He reported that statins do not reduce the overall risk of death in such a low-risk population and that there was a:

“• small (though statistically significant) reduction in the risk of nonfatal heart attack and stroke — 140 people with low risk (less than 20 percent five-year risk) must take a statin for five years to prevent one nonfatal event (NNT [number needed to treat] = 140)”

Others maintain that the NNT for statins to prevent heart attacks is substantially lower…but no one suggests it is anywhere close to 10.

Can Vitamin C Help in Combatting the Common Cold Duration?

Here is where Hemilä and Chalker state that vitamin C shines:

“In contrast to the variation in the effects of vitamin C on common cold incidence, the effects on common cold duration and severity are more uniform. The 2013 Cochrane review found that in 17 trials with 7215 adults, regular vitamin C (≥0.2 g/day) shortened colds by 7.7%, and in 10 trials with 1532 children, regular vitamin C (≥1 g/day) shortened colds by 18%.

“In the 2023 analysis, we focused on the effect of regular vitamin C with dose ≥1 g/day on common cold severity. In 15 RCTs with 6244 participants, vitamin C decreased the severity of colds occurring during the supplementation period by 15%. In a direct comparison of the effect of vitamin C on the total duration of colds and on the severity of cold symptoms, there was a significantly greater effect on severity.”

Their Conclusions:

“There is no rationale for the general Western population to take vitamin C regularly with the goal of reducing the incidence of cold episodes. However, there is consistent evidence from regular supplementation trials that vitamin C has an effect on common cold severity and duration. Given this, if a person suffers from frequent colds, it is reasonable to test individually whether he or she may benefit from vitamin C supplementation during the winter.”

I make no recommendations about a helpful dose of vitamin C. The authors of this overview conclude:

“For all common cold patients, it is not unreasonable to test whether 6–8 g/day therapeutic vitamin C appears beneficial, starting soon after the onset of symptoms.”

That seems high to me. Some people report diarrhea after large doses. I imagine that individuals will need to determine what works best for them.

Final Words:

Vitamin C is inexpensive. Drug companies are not going to spend money on something that they cannot patent. Large health organizations like the National Institutes of Health have written vitamin C off and are unlikely to sponsor a really large, long-lasting clinical trial to test various doses of vitamin C for combatting the common cold.

And something that has been overlooked for decades is that the “common cold” is not one single entity. There are literally hundreds of viruses (and some bacteria) that can trigger upper respiratory tract symptoms. They include rhinoviruses, coronaviruses, adenoviruses and enteroviruses. Let’s not forget parainfluenza virus and respiratory syncytial virus (RSV). Then there is human metapneumovirus (HMPV).

Bacteria can also cause sore throat, stuffy nose and cough. There is Haemophilus influenzae, Mycoplasma pneumonia, Streptococcus pneumonia, Moraxella catarrhalis, Bordetella pertussis (whooping cough), Burkholderia pseudomallei and Chlamydophila pneumoniae. Which, if any, of these bacterial infections might respond to vitamin C? We have no idea. Assuming that all viruses should respond equally to vitamin C would be like assuming that every bacterial infection could be cured with penicillin.

Learn & Share:

Please share your own experience with vitamin C in the comment section below. And if you would like to learn more about other approaches, our eGuide to Colds, Coughs & the Flu may be helpful. Here is a link to all our Health eGuides.

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