There has been a lot of talk about whether vitamin C will help prevent or treat COVID-19. To date, the safety and efficacy of vitamin C has not been established for the prevention or treatment of COVID-19.
However, there has been quality studies on the role of vitamin C and common colds.
Vitamin C Supplementation
Vitamin C is an essential water-soluble vitamin in our diets. It acts as an antioxidant – this means it plays a role in our immune functions and protection against infections. Vitamin C is also import for the synthesis of hormones, collagen, and neurotransmitters.
Vitamin C in your Diet
The most common foods that contain vitamin C include:
- Citrus fruits like oranges or grapefruit
- Broccoli, cauliflower or cabbage
- Fortified juices or foods
It doesn’t take a lot of food to reach the recommended intake of vitamin C daily. As little as ¾ cup of orange juice or ½ cup of strawberries can give you 50% of what is required to prevent deficiency. The average adult male requires 90mg of vitamin C per day. The average adult female requires 75mg of vitamin C per day.
By following Canada’s Food Guide and aiming for half your plate to be vegetables and fruits, you will have more than enough vitamin C in your diet.
Infants being fed breast milk or formula receive adequate vitamin C.
Vitamin C and the Common Cold
A Cochrane review published in 2013 has summarized the evidence for vitamin C in preventing and treating the symptoms of the common cold.
Unfortunately, supplementing vitamin C beyond 200mg per day does not reduce the incidence of the common cold in the general population. Supplementing vitamin C may reduce the duration of a common cold, but these results are not consistently found in studies. Starting vitamin C after symptoms of a cold start shows no benefit.
High Doses of Vitamin C
Vitamin C taken in excess will generally not have any toxic side effects. Because it is water soluble, your body will excrete any vitamin C that it does not require.
Most common side effects may include diarrhea, nausea, or abdominal cramps.
A more rare side effect of high doses of vitamin C is kidney stones. This is more likely to occur in patients with kidney disease or in children under the age of 2 if taking high doses.