Clarifying the Vitamin C-Coronavirus Question

vitamin c coronavirusAuthor: Lily Mazzarella, MS, CNS

At Farmacopia, we have been getting questions about vitamin C.  You’ve probably all heard reports of vitamin C emerging as treatment for Covid-19, based on clinical trials in China, which led to the inclusion of the nutrient in official guidelines for treatment of the virus.  There is also a clinical trial underway in the US to explore the possible role for vitamin C in the management of severe Covid-19 pneumonia.  

So let’s take a look at what we do and don’t know about vitamin C and Covid-19. 

What we don’t know:

Vitamin C has not been proven to prevent or treat Covid-19, in supplemental (over the counter) form, or in IV form.  Several research studies do suggest that high-dose IV vitamin C may improve outcomes for critically ill Covid-19 patients receiving other forms of treatment in hospital settings.  

Here’s what we DO know:  

In China , very high dose intravenous Vitamin C (approximately 24 grams per day) is being used alongside other treatments, such as heparin (an anticoagulant), antimalarial medications, antibiotics and other interventions to manage seriously ill Covid-19 patients.  

On Long Island, New York at the Northwell Hospitals, pulmonologist and critical care specialist Dr. Andrew Weber has been administering 1.5 grams of intravenous vitamin C to critically ill patients with the virus, and then re-administering this amount several times throughout the day to counter the sepsis-related drop in vitamin C these patients may experience.  The vitamin C is given alongside all other treatments listed above.  

Vitamin C plays a vital role in healthy function of the immune and respiratory systems.  According to the Linus Pauling Institute*, a nutritional research center at Oregon State University, vitamin C influences several components of the human immune system.  It has been shown to stimulate both the production and function of white blood cells, including neutrophils, lymphocytes, and phagocytes, all of which are involved in fighting infection.  Vitamin C accumulates in these cells and protects them from the oxidative stress that occurs when they engage in their explosive battles against invading microorganisms.  In vitro studies have shown that vitamin C increases interferon production in white blood cells, a chemical that is specific to our body’s fight against viruses.  Vitamin C is one of our most important antioxidants, aiding in the recycling of other antioxidants, like vitamin E.

Smokers have higher vitamin C requirements than non-smokers.  We also know that smokers are at higher risk of complications from Covid-19.   

So, let’s learn a little about this incredibly important nutrient—what it does for us, what it doesn’t, and where to get it.

Vitamin C is an essential nutrient, meaning that unlike most other animals, we humans cannot synthesize Vitamin C endogenously.  That means we must obtain it from our diets.  If we don’t, we’re at risk for scurvy, or vitamin C deficiency, in which we literally start to come apart:  C is required for the formation and maintenance of all of our collagen.  And collagen is the foundation of our connective tissues, including blood vessels, cartilage, and bone.  It’s an important antioxidant in the immune system and central nervous system; highest C concentration in the human body occur in white blood cells, the brain, and the eyes, as well as the adrenal glands.

Should I supplement?

Vitamin C, a.k.a. ascorbic acid, can be taken in supplement form, although studies suggest that not more than 200-300 mg can be absorbed at a time (for more info, see this NIH factsheet).  C is water-soluble and we excrete much of it unchanged in the urine when we take doses above 2000 mg/day (aka “pee it out”).  Higher dose supplementation can also cause loose stools and gastrointestinal upset, as unabsorbed C exerts an osmotic pull of water into your bowels.

I do recommend vitamin C supplementation to my clients—but I suggest they use lower dose (500 mg) pills, or a food-based powder.  If higher doses are desired, the amount can be divided throughout the day.  Ester-C may be helpful for people with sensitive GI tracts, and one study did show that this (more expensive) form raised leukocyte levels faster than plain old ascorbic acid.  Of course, I’m AM a huge fan of getting it from the best possible source:  our food.

Where do we get it?

Wondering how to eat those herbs?

  • Make a delicious pesto with your parsley and eat by the spoonful! Here’s our recipe.
  • At 540 mg of vitamin C per cup, rose hips are a potent ally. I recommend making a rose hip jelly!  Recipe here.
  • Ever try hibiscus flower tea? Cultures world-round have been brewing up these vitamin C rich petals for ages.  Hibiscus supports the cardiovascular system and can help reduce hot flashes in some individuals. Gaia Herbs makes a great pre-bagged one.  

Though boiling and cooking does destroy some vitamin C content (see below), I believe that in most cases, the lower amounts (as compared to a supplement) from a food or tea are still valuable and essential for our health.  

What about oranges?  Let’s be fair:  oranges are delightful.  Oranges contain carotenes, flavonoids, fiber, and a host of complex, beneficial constituents like limonoids.  Kids love them, and they are hydrating. But if you’re going to do juice, do it yourself: buy organic and juice the WHOLE orange—peel and pith included (or at least a few of the peels).  This will give provide abundant bittersweet aromatic components, as well as flavonoids like rutin, which help to strengthen your blood vessels and stabilize inflammatory mast cells.  Many store-bought juices are spiked with high-fructose corn syrup, and many contain as much sugar as soda. Or, simply eat the whole orange instead of drinking juice.

Does cooking destroy vitamin C?

The short answer is:  yes.  But it doesn’t destroy all of it, and the amount of loss varies dramatically depending upon the cooking method and food in question.  According to a study at UC Davis, home cooking methods destroy 15-55% of vitamin C in commonly consumed foods.  Freezing preserves C better than canning for most fruits and veggies, though it can be lost over long storage time (think of all those ice-crystal filled bags in your freezer.  Might be time to compost!).  Boiling and frying destroy more C than other methods, while pressure cooking and microwaving preserve the most C.  Overall, they concluded that fresh is best for vitamin C content, with a couple of interesting exceptions:  “cooked frozen peas and frozen leaf spinach (versus frozen chopped) contained amounts of ascorbic acid greater than or equal to those in the cooked fresh products.”

Does Vitamin C protect us from the common cold?  Or speed our recovery once we contract it?

While most meta-analyses on regular vitamin C supplementation (greater than 200 mg) have failed to demonstrate prevention of the common cold, except in certain cases of extreme physical activity (eg, endurance athletes), research does suggest that it can shorten the duration of the common cold, especially in children.  Once a cold is underway, no significant effect vitamin C supplementation has been observed in therapeutic trials.  However, when 1000 mg of vitamin C was combined with 10 mg of Zinc, rhinorrhea (runny nose) was significantly reduced over 5 days of treatment.

Special evidence

Vitamin C supplementation (greater than 200 mg) appears to have specific benefits in these groups:

  • Children
  • People doing extreme physical exercise and/or exposed to very cold temperatures: vitamin C supplementation can halve the incidence of colds in these groups!
  • Common cold-induced asthma

Fun Vitamin C facts

In Arctic cultures, whale skin is prized as the best source of vitamin C in the diet

Vitamin C aids absorption of non-heme (plant-based) iron

In addition to vitamin C, pineapple contains mucus-thinning bromelain, a proteolytic enzyme, making it a double-win for cold season!

In addition to collagen, vitamin C is required for the biosynthesis of L-carnitine, and catecholamines—neurotransmitters like norepinephrine and dopamine, as well as serotonin and acetylcholine.  It is also necessary for proper synaptic transmission of these important neurotransmitters.

Flavonoids—ubiquitous plant kingdom compounds found in green tea, chocolate, citrus, blueberries, cherries—may increase intra-cellular utilization of vitamin C, and with C, aid in collagen formation.  Vitamin C and the flavonoid quercetin appear to have a synergistic anti-allergic effect.

Vitamin C (or lemon juice) taken with green tea can increase the absorption of green tea catechins, well-researched antioxidant compounds, by up to 13 times!

Your C requirements are higher if…

  • You smoke
  • You are healing from a wound, burn, or surgery
  • You have gastrointestinal inflammation (Crohn’s, Colitis, or parasites)
  • You are pregnant, or breastfeeding
  • You have adrenal fatigue
  • You exercise heavily

*Linus who?

Linus Pauling was the double Nobel Laureate (Chemistry and Peace) who posited that large doses of vitamin C (more than 1000 mg/day) could be used to prevent the common cold.  He published 2 books:  Vitamin C and the Common Cold, and Vitamin C and Cancer, which sparked public interest in high-dose C therapy.  This kind of supplementation is still used by functional nutrition practitioners and functional medicine physicians to support people with a variety of chronic health conditions, including cancer, heavy metal toxicity, Lyme disease, and viral infections. 


The statements in this article are meant to be informative, not to diagnose or prescribe any treatment of symptom or disease. The statements in this article have not been evaluated by the FDA. 

Lily Mazzarella is not a medical doctor, and does not take the place of a medical doctor. She is a Clinical Herbalist and Certified Nutrition Specialist, and offers information and guidelines pertinent to her field of Health. Farmacopia is a center for health promotion and information.

Back to blog