Vitamin C for your Immune System

By: Leigh Matthews

If you’re especially concerned about immunity this fall, you’re not alone. With many children back in school, parents and caregivers back in the workplace, and more time spent indoors, the chances of picking up a virus or bug can increase sharply. Getting sick is not an inevitability, though. Good hygiene practices, physical distancing, and face coverings can all help keep your risk of infection and of infecting others low. As always, you can support your natural immune defences by getting enough sleep, exercising regularly, and eating a healthy, balanced diet which provides key nutrients such as vitamin C. But how does vitamin C support the immune system?

Vitamin C – vital for immune function

Vitamin C plays several important roles in immune system function. This nutrient increases levels of interferon, a type of protein that helps prevent viruses from entering healthy cells.[1] Vitamin C also reduces bacterial activity and stimulates phagocytosis, i.e., the process where white blood cells consume and destroy pathogens.1

Vitamin C is also vital for the formation of collagen. While you might think this is important for keeping your skin looking fresh and youthful, collagen formation is actually key to all-round good health. Why? Because with vitamin C’s help, the body can form the right form [ST1] of collagen to enable timely wound repair, support healthy gums, strong bones and teeth, and support blood vessel walls and prevent bruising.1

Healthy gums and skin are key parts of the body’s first line of defence against pathogens that can cause infection.[2] Healthy blood vessels are vital for getting immune system cells to where they’re needed to fight infection, ​ to deliver nutrients and remove waste products.

Vitamin C also has considerable antioxidant and free radical scavenging effects, which help prevent damage to DNA, cells, and tissues.[3] Damaged tissue is more vulnerable to infection, so a good intake of antioxidants such as vitamin C can help keep your body protected.

Can vitamin C help reduce symptoms of colds?

Vitamin C has long been seen as a key nutrient for fighting off coughs and colds, and for a good reason. While it doesn’t seem that vitamin C helps prevent colds in the average person, it has been seen to decrease the duration of colds by 1–1.5 days if taken at the onset of symptoms. It may also help prevent colds in people exposed to physical and environmental stresses, such as very cold winters.[4]

And, if you’re looking at a fall marathon or other intense physical activity, you might want to stock up on vitamin C. That’s because there is some evidence that taking 600–1000 mg of vitamin C per day for 3–8 weeks before intense physical exercise, such as a marathon, can prevent upper respiratory tract infections.[5] [6]

Why do you need vitamin C daily?
Vitamin C is a powerful water-soluble antioxidant that protects the aqueous (watery) parts of the body from oxidative damage, including free radicals. Aqueous areas of the body include your blood and the fluid between cells and fluid between tissues.

While the water solubility of vitamin C is beneficial for these tissues, there is a downside: your body cannot store vitamin C, unlike fat-soluble vitamins that accumulate in tissues.

A good daily intake of vitamin C is therefore essential, especially as flu season begins in October and continues until the end of May.[7] Ideally, you’ll get all the vitamin C you need from food, including fresh and frozen fruits and vegetables. If you’re not sure you’re getting enough, or are struggling to eat your vegetables, vitamin C supplements offer a convenient way to make up for shortfalls. Supplements are also helpful when your need for vitamin C increases, such as if you’re very physically active, regularly suffer from colds, or if you smoke.

Natural Factors offers a variety of convenient ways to top up your vitamin C intake, including tablets, powders, and chewable wafers. If you’re looking to take a higher dose of vitamin C and are concerned about potential gastrointestinal upset, consider Natural Factors BioCgel™. This high-absorption formula features pH-neutral calcium ascorbate that is easy on the stomach alongside citrus bioflavonoids and the proprietary whole fruit blend BerryRich® for enhanced absorption and additional antioxidant protection.

Finally, if you’re looking for a little extra immune support for your kid(s) this fall and winter, Big Friends® Vitamin C provides 250 mg of this essential nutrient in every tangy orange chewable tablet.


[1] Iqbal K, Khan A, Khattak M. Biological significance of ascorbic acid (vitamin C) in human health – A review. Pakistan Journal of Nutrition. 2004;  3(1):5-13.

[2] Schor E. (Ed.). Caring for Your School-Age Child: Ages 5 to 12. New York, NY: Bantam Books; 2004

[3] Levine M, Rumsey SC, Daruwala R, et al. Criteria and recommendations for vitamin C intake. Journal of the American Medical Association. 1999;281:1415-1423.

[4] Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2013;1:CD000980.

[5] Moreira A, Kekkonen RA, Delgado L, et al. Nutritional modulation of exercise-induced immunodepression in athletes: a systematic review and meta-analysis. European Journal of Clinical Nutrition. 2007;61(4):443-460.

[6] Hemilä H. Vitamin C and common cold incidence: a review of studies with subjects under heavy physical stress. International Journal of Sports Medicine. 1996;17:379-383.

[7] Government of Canada. (2020). Annual Influenza Report. Available from: https://www.canada.ca/en/public-health/services/diseases/flu-influenza/influenza-surveillance/annual-reports.html

 [ST1]Suggest: form. “kind of collagen” suggests the type of collagen, the paper talks about the configuration of collagen

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