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Vitamin C Intake in Relation to COVID-19

Note: This article is to be used as an informative guide and not as a physiological advice, if you or anyone you know is experiencing COVID-19 symptoms, call your primary care physician or nearest pharmacy.

For more information: (McGill staff and students) (Canadian residents)

Why would Vitamin C intake be of interest as a possible treatment for COVID-19?

The DHNUS blog has already covered Vitamin C intake in relation to the common cold. To recap, slightly increasing your Vitamin C intake from the RDA (75-90mg/day) may assist in reducing the duration and severity of flu symptoms ((Hemilä, 2007).

Generally, regular use of Vitamin C supplements may shorten the duration of your symptoms, but it will not reduce your risk of contracting a cold. Although taking Vitamin C supplements does boost immunity and seems to exhibit an antiviral effect (if you keep dosage within the RDA limits), once you have contracted a cold and are experiencing symptoms, increasing vitamin C dosage seems to have no proven significant benefits (Hemilä, 2007).

COVID-19 is by no means “just another flu” however, for some infected patients, symptoms may be similar to those of the seasonal flu virus. Thus, begging the question; Could upping your Vitamin C intake decrease the severity of COVID-19 symptoms?

Retrieved from National Institutes of Health (NIH)

Background Information: What is Vitamin C and where can you find some?

Vitamin C (Ascorbic Acid) is a water-soluble chemical that we must get from a diet so all the processes in our bodies can function to help us maintain a balanced internal state even as external environments change (homeostasis). When our bodies fall out of this dynamic state of balance, we get sick and are susceptible to infection (Whitney, 2019).

Vitamin C is involved in all sorts of processes in the body including; maintaining your bones, helping your wounds heal, assisting in Fe absorption, and, it even acts as an antioxidant that protects the tissues in your body from being degraded (Whitney, 2019).

Vitamin C sources are abundant in a diverse diet. You can find it in broccoli, tomatoes, fortified milk, and even kiwis. However, meeting the Vitamin C daily requirement, is difficult without eating your fruits and green vegetables. Vitamin C supplements are also readily available and abundant to help you meet and not exceed your daily intake (Whitney, 2019).

How would Vitamin C could help mitigate COVID-19 symptoms?

In severely symptomatic COVID-19 patients, dangerous levels of inflammation occur in the lungs and other organs. After contracting the virus, the patient’s body has an extreme response that stresses the immune cells. These immune cells all go to the cite of infection and try to destroy the virus, but instead of destroying the virus, it only makes the situation worse because the cells begin sticking together and clogging the capillaries. This causes inflammation and fluid retention that damages the organs. This extreme inflammatory immune response is known as sepsis and if untreated may be life-threatening. Early studies have shown that Vitamin C can help eliminate the accumulation of fluid and prevent the coagulation (sticking) of cells in the lungs (Liu, 2020).

Also, critically ill patients tend to have lower vitamin C levels in the blood. This may mean that the body has greater need for vitamin C when under severe stress. Therefore, it makes sense that vitamin C supplementation may assist managing symptoms (Hemilä, 2020).

What does the research indicate?

The expert group on clinical treatment of COVID-19 (Shanghai Expert Panel), studied the use intravenous ascorbic acid (IVAA)1 as an adjunctive care.2 The Shanghai Expert Panel found that COVID-19 patients placed on the IVAA treatment had a hospital stay that was 3-5 days shorter than those without the treatments. This is particularly advantageous as shorter hospital stays are not only cost efficient for both hospital and patient but, it also frees up severely needed hospital space (ISOM, 2020).

The doses used for IVAA were 100-200mg/day of continuous infusion for hospitalized patients which is pretty high compared to the RDA. High doses were used as a previous meta-analysis concluded that: the sicker a patient is, the more likely they are to benefit from Vitamin C supplementation (Hemilä, 2020). Furthermore, higher doses of Vitamin C are more effective as oxidative therapy,3 require less prior screening of patents (G6PD screening4) and ensure that the tissues of the blood and lungs are protected from further inflammation (ISOM, 2020).

What is the current medical consensus? What steps are currently being taken for further research?

Currently, according to the NY Post, seriously sick patients in New York State’s largest hospital system are being administered enormous amounts of Vitamin C based on reports from the Shanghai Expert group.

Due to the lack of a double-blind-placebo controlled study, there is no consensus as to whether vitamin C would be an effective adjunctive care for COVID-19 patients. Such a study is currently on the way and is due to be published within this year (National Clinical Trial number: NCT04264533). Similar studies are being conducted for Vitamin E, A and D.

What should you do?

Follow the standard RDAs for vitamin C intake as overdose may lead to toxicity with symptoms including, but not limited to, gastrointestinal distress and diarrhea (Whitney, 2019).

If you have COVID-19 symptoms or you suspect that you have contracted COVID-19, follow the Gouvrenement du Quebec Guidelines:


  1. IVAA: Vitamin C solution placed in an IV bag and given to the patient via a drip

  2. Adjunctive Care: Treatments used in combination with others

  3. Oxidative Therapy: Treatments that increase blood tissue oxygenation, stimulate metabolic processes and enhance immune function

  4. G6PD Screening - measures the levels of glucose-6-phosphate dehydrogenase (G6PD), an enzyme in your blood important for red blood cell function


Hemilä, Harri, et al. “Vitamin C for Preventing and Treating the Common Cold.” Cochrane Database of Systematic Reviews, 2007, doi:10.1002/14651858.cd000980.pub3.

Hemilä, Harri, and Elizabeth Chalker. “Vitamin C May Reduce the Duration of Mechanical Ventilation in Critically Ill Patients: a Meta-Regression Analysis.” Journal of Intensive Care, vol. 8, no. 1, 2020, doi:10.1186/s40560-020-0432-y.

“Intravenous Ascorbic Acid for Supportive Treatment in Hospitalized COVID-19 Patients.” ISOM, International Society for Orthomolecular Medicine, 27 Aug. 2020,

Liu, Fang, et al. “Intravenous High-Dose Vitamin C for the Treatment of Severe COVID-19: Study Protocol for a Multicentre Randomised Controlled Trial.” BMJ Open, vol. 10, no. 7, 2020, doi:10.1136/bmjopen-2020-039519.

Mongelli, Lorena, and Bruce Golding. “New York Hospitals Treating Coronavirus Patients with Vitamin C.” New York Post, New York Post, 25 Mar. 2020,

Stacey Burling Tribune News Service. “The Changing Face of COVID-19 Care.” EMS World, 4 Oct. 2020,

“Vitamin C Infusion for the Treatment of Severe 2019-NCoV Infected.”, ZhiYong Peng, 0AD,

Whitney, Eleanor Noss, and Sharon Rady Rolfes. Understanding Nutrition. Cengage, 2019.

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