Contrary to the general consensus, taking ascorbic acid to boost immunity is somewhat a hoax.

Yes, there is some scientific evidence to suggest it can help with some viral infections.

No, taking massive amounts isn’t good for you. In fact, high dosages hurt you.

This is because vitamin C is both an antioxidant and a pro-oxidant. That means it can generate free radicals.

Only some antioxidants have this drawback.

diagram of Fenton and Haber-Weiss reactionsHow it works with C is a process called the Fenton reaction.

As you can probably guess from the diagram, it’s a bit complicated to explain in anything less than a page. In a nutshell, the vitamin C molecule sets off a chain reaction with metal ions (like iron) in your body. That generates free radicals.

Does vitamin C protect you from coronavirus?

No, that’s a myth. There are rumors circulating some areas of the internet (i.e. TikTok) that you should take vitamin C supplements to prevent getting COVID-19, as well as to treat and cure it. There is no research to suggest any such claims are true!

It’s dangerous that people are saying that. What we all need to focus on are proven protective measures, like hand washing and other sanitary countermeasures.

That said, surprisingly, there is some very preliminary research looking at ascorbic acid and this category of viruses. There’s even a human clinical trial for COVID-19 which was just announced. It’s a legit one too, registered in the FDA database.

What the research really says

Before the COVID-19 outbreak of 2020, there are a few pieces of peer-reviewed medical literature in the US government’s PubMed database about how coronaviruses behave when vitamin C is present. Most are related to avian forms, which affect chickens. What follows is that related to humans.

Amylmetacresol/2,4-dichlorobenzyl alcohol, hexylresorcinol, or carrageenan lozenges as active treatments for sore throat.

Marinomed Biotechnologie GmbH, Vienna, Austria – 2017

This study looked at several versions of throat lozenges, including those containing vitamin C. They tested them against human rhinovirus (HRV) 1a, HRV8, influenza virus A H1N1n, coxsackievirus A10, and human coronavirus (hCoV) OC43. The latter is a coronavirus but not the same as the COVID-19 form.

The results may surprise you as to which worked best:

“…we showed that binding and inactivation of virus particles by iota-carrageenan are fast and highly effective. During the residence time of the lozenge in the mouth, the viral titer is reduced by 85% and 91% for influenza A virus and human coronavirus hCoV OC43, respectively. Carrageenan-containing lozenges are, therefore, suitable as causative therapy against viral infections of the throat.”

That’s right, carrageenan-based lozenges worked better than those with ascorbic acid. You know, carrageenan is that stuff in some almond and non-dairy milks that everyone says is bad for you. (1)

Vitamin C and SARS coronavirus

Journal of Antimicrobial Chemotherapy – 2003

This is not a study. Rather, it’s just a letter published in a medical journal by a Finnish doctor advocating for the study and potential usage of ascorbic acid during the SARS outbreak (which is another type of coronavirus). Here’s a quote from his letter:

“Recently, a new coronavirus was identified as the cause of the severe acute respiratory syndrome (SARS). In the absence of a specific treatment for SARS, the possibility that vitamin C may show non-specific effects on severe viral respiratory tract infections should be considered. There are numerous reports indicating that vitamin C may affect the immune system, for example the function of phagocytes, transformation of T lymphocytes and production of interferon.”

He goes on comparing the benefits and similarities for use in colds, flu, and pneumonia:

“Placebo-controlled trials have shown quite consistently that the duration and severity of common cold episodes are reduced in the vitamin C groups, indicating that viral respiratory infections in humans are affected by vitamin C levels. There is also evidence indicating that vitamin C may affect pneumonia. In particular, three controlled trials with human subjects reported a significantly lower incidence of pneumonia in vitamin C-supplemented groups, suggesting that vitamin C may affect susceptibility to lower respiratory tract infections under certain conditions.”

He cites all of the above claims in the letter. Interesting, but this is an opinion piece and not a study. (2)

Clinical trial using vitamin C for COVID-19

On Februay 11, 2020, a Chinese hospital posted their intent to begin a human clinical trial on vitamin C infusions for the treatment of the new coronavirus.

vitamin C coronavirus human clinical trial

They’re aiming for 140 participants, who will be randomized and treated in a triple-blinded manner.

The dosage used in the treatment of COVID-19 will be 24 grams of vitamin C, infused by IV for 7 days, at a rate of 7 mL per hour.

The placebo group will be given 50 mL of water per day instead, infused at the same speed.

It will be interesting to see how this pans out. They expect completion by September 30th but the dates on clinical trials are always a moving target. In fact, most entered in the NIH’s clinical trials system don’t ever end up completed. (3)

Should you use it for immune support?

We’ve presented all the science but in case it’s not crystal clear, vitamin C is NOT a treatment, prevention, or cure for COVID-19 or any other type of coronavirus.

That being said, it’s never a bad idea to supplement with it for your general health and immune support. After all, it is an essential vitamin. The richest natural food source of this vitamin a camu camu. But don’t take too much vitamin C.