Is vitamin C effective in preventing or treating COVID-19?
(We recommend reading this post to learn about the basics of evidence-based medicine and the findings on COVID-19.)
Based on: No direct scientific evidence. Indirect evidence about other respiratory infections.
Today, there are no specific treatments for COVID-19. At the same time, there is a general belief that vitamin C strengthens the immune system and is effective for preventing or treating respiratory infections like the common cold. In this context, vitamin C has come up as a possibly useful intervention for preventing or treating COVID-19 disease.
Unfortunately, contrary to popular belief, there is evidence that vitamin C does not decrease the incidence of the common cold and does not play a role in its treatment. Also, there is no evidence of vitamin C having any benefit for patients with more severe infections.
So what do we know today about its efficacy on COVID-19 or other coronavirus infections?
After extensive scrutiny (systematic review) of all published studies of COVID-19, SARS, and MERS, our team found no evidence from human studies addressing the impact of vitamin C for the prevention or treatment of coronavirus infections (SARS, MERS or COVID-19).
It is important to note that the absence of evidence does not mean that an intervention is not effective. It just means that we still do not know for sure if it is effective or not. However, in the case of vitamin C, if we extrapolate the high certainty evidence about the lack of efficacy in other infections, the conclusion is that it probably does not play a role in COVID-19.
In this sense, it is worth mentioning that we identified a trial that could shed light on the role of vitamin C for COVID-19. It is a randomized trial that will recruit 140 patients with severe COVID-19 pneumonia. Half of the patients will receive 12 grams of injected vitamin C (with sterile water), 2 times a day for 7 days; the other half will be offered a placebo (sterile water only), also twice a day for 7 days.