Vitamin C: Everything You Need To Know

What do you know about vitamin C? You may know the little orange chewables often administered in winter as a kid? You may know that vitamin C generally helps with cold symptoms? Is that the end of the story for vitamin C? Hardly. Vitamin C is a very important vitamin used in lots of body systems, that’s thankfully super easy to get from your diet. 

Vitamin C is a powerful antioxidant, which is required for collagen synthesis and is widely utilised by white blood cells in the immune system. Much like zinc, vitamin C is an incredible nutrient, integral to our health and wellbeing. Read on for everything you need to know about vitamin C, including why we need it and my rapid-fire protective vitamin C smoothie.

What is Vitamin C?

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin essential for human health. Many other mammals can make vitamin C, however us humans need to obtain vitamin C from our diet. Vitamin C is an essential cofactor nutrient in the body. This means vitamin C is required to switch on and off various enzymatic reactions and processes. Vitamin C is usually readily absorbed in the body. Good stress responses from the adrenal system depend on vitamin C adequacy. 

Vitamin C protects cells from damage, this includes DNA, proteins and fat cells. Vitamin C quenches or reduces the damaging effects of free radical compounds. Vitamin C is also involved with gene expression and helps regulate DNA function.

Fun fact: vitamin C recycles other antioxidants in the body. Did you know that vitamin C helps regenerate vitamin E?

Vitamin C History

In 1734, the Dutch writer Johann Bachstrom made the assertion, "scurvy is solely owing to a total abstinence from fresh vegetable food, and greens. This idea sparked the notion that a nutrient deficiency could cause disease. It would still take another couple of hundred years before a vitamin would be officially discovered and for the hypothesis to be confirmed.

Fruits and vegetables containing Vitamin C on a dark background

In 1747, a British Royal Navy surgeon was the first to formally identify that fresh fruit, namely lemons and oranges, prevented the onset of scurvy. He published his findings in the book Treatise on the Scurvy in 1753. This condition afflicted sailors embarking upon long voyages, where storing foods other than bread and rum proved problematic. These poor naval folk, incidentally suffering from severe vitamin C deficiency or scurvy, experienced poor wound healing, thinning hair, tooth decay and in many instances, death. 

From 1796 onward, the British Navy had lemon juice on hand as common practice whilst traversing rough seas. By the 19th century, alongside limes, lemons and oranges, other foods were praised as scurvy preventatives, including sauerkraut and malt. 

Vitamin C was eventually isolated and synthesised in a lab in 1928 and 1933, respectively. Since then, it has been used as a food preservative in commercial food production. Over the last 100 years plenty of research involving humans and animals has revealed the many biological functions of vitamin C.  

Why Do We Need Vitamin C?

Vitamin C is crucial for several enzymatic reactions in the body. It’s also involved in bolstering immune cells. Vitamin C is found abundantly in the adrenals, bone and connective tissue, the liver, ovaries and pituitary gland. This vitamin has a broad protective effect against inflammation, whether that be from internal or external sources. Adequate vitamin C levels are associated with lower risks of cancer, heart disease and stroke. Because vitamin C is ubiquitous among many body cells, the protective effects can be observed in various ways. Here’s some of the research on vitamin C and why it's so important. 

Orange juice in a jar next to a bowl of oranges cut in half

Vitamin C Health Benefits

Asthma & Respiratory Health

Vitamin C has long been associated with preventing colds, flus and other seasonal respiratory illnesses. A 2013 meta-analysis of 53 trials assessed the effects of vitamin C supplementation on the incidence, duration and severity of the common cold. The results showed that frequent supplementation with vitamin C reduced the duration of colds, especially in children compared to adults. 

Vitamin C helps to slow down and stabilise histamine responses associated with asthma. This finding was identified in several clinical trials, showing encouraging effects of vitamin C supplementation. Between 1 and 5 grams (around a teaspoon) of vitamin C has a protective effect in asthma episodes, in both frequency and intensity. 

White blood cells use vitamin C as their weaponry against infection. Vitamin C accumulates in these cells (leukocytes) and in the presence of an infective agent, vitamin C is rapidly utilised. One study has shown that patients suffering from pneumonia had a reduction in the severity and duration of their illness upon vitamin C administration.

Skin & Wound Healing

Looking after your skin is a very important and often forgotten aspect of maintaining your health. Our skin is constantly exposed to and interfacing with the external environment. This means that skin is vulnerable to damage from things like the sun, cosmetics and other chemicals. Vitamin C is one of the most important vitamins involved in skin health. Vitamin C is required as a primary nutrient cofactor to make collagen. This gives skin a youthful appearance and soft elasticity. Vitamin C also scavenges and neutralises free radicals, as a result of UV radiation, chemical exposure and pollution, which helps slow down effects of ageing.

Vitamin C is involved in cell signalling pathways that trigger keratinocyte (skin cell) formation. Moreover, several studies have shown that vitamin C is integral for dermal fibroblast growth, which directly influences the speed of wound healing. Under a microscope, it’s observed that vitamin C accumulates within intracellular compartments of body tissues. Reserves of vitamin C are located within easy access for cells when your skin needs repairing. It’s easy to see that vitamin C has many functions in protecting skin from damage as well as promoting new cell growth and tissue regeneration.

Cardiovascular Health

There’s several ways vitamin C helps improve and maintain cardiovascular health. A major review published in the International journal of molecular sciences, found that vitamin C was crucial in the preservation of heart and blood vessels. Vitamin C is a universal antioxidant, which protects blood vessels from free radical damage. Vitamin C also helps reduce the accumulation of white blood cells on vessel walls. This accumulation is an early sign of atherosclerosis. Vitamin C appears to increase nitric oxide production which improves vasodilation and helps regulate blood pressure. 


Over the past few decades, vitamin C has been a popular adjunctive therapy in cancer treatment. A 2018 systematic review examined the beneficial effects of vitamin C in cancer patients. Notably, vitamin C helps reduce fatigue, inflammation and also helps improve overall quality of life. A 2014 meta-analysis published in the European Journal of Cancer found that vitamin C supplementation could be associated with a reduced risk of mortality from breast cancer. Most studies affirm that patients who have a robust immune system have the best chance of benefiting from vitamin C as an integrative cancer therapy. 

Wooden box of fruit containing Vitamin C

Food Sources of Vitamin C

  • Kakadu Plum
  • Acerola Berries
  • Kiwifruit
  • Rosehip
  • Guava
  • Blackcurrant
  • Grapefruit
  • Orange juice
  • Strawberries
  • Red capsicum
  • Cooked broccoli
  • Brussel sprouts
  • White potato
  • Papaya
  • Pineapple
  • Tomatoes
  • Bananas
  • Apple
  • Spinach

Recommended Dietary Intake

The generally recommended intakes for vitamin C tend to vary depending on countries, different populations and the institutions conducting public health research. Different life stages and periods of growth require varying amounts of vitamin C from the diet. Most adults will require between 45-65 mg/day of vitamin C for optimal function. If you’re pregnant or breastfeeding, your requirements are slightly higher at around 80 mg/day. 


Severe vitamin C deficiency is mostly rare in modern diets. Major vitamin C deficiency has been famously documented for centuries amongst seafarers as scurvy. Scurvy can include symptoms such as bleeding, hair loss, connective tissue damage, bone degradation and death. Mild symptoms of vitamin C deficiency are much more common. This could present as loss of skin elasticity, poor wound healing, impaired stress responses and bruising. As long as you’re enjoying a wholefoods diet, full of fresh leafy greens, fruits, vegetables and quality animal protein where possible, your vitamin C levels should be replete. 


It’s rare to experience an excess in vitamin C if it’s coming from food sources in fruits and vegetables. In almost all instances, vitamin C overdose occurs from supplementation. One of the first signs you’ve reached an upper limit of vitamin C is when you find yourself running to the toilet. This is known as ‘bowel tolerance’ and it’s an indicator to reduce or stop vitamin C supplementation. 

Signs and symptoms to look out for are diarrhoea, stomach cramps, increased risk of kidney stones and dizziness. The good news is that because vitamin C is water-soluble and used readily, most side effects experienced from excess consumption usually resolve quickly. Of course, if you’re experiencing any health issues or symptoms similar to those above, consult your health provider. 

Vitamin C supplements

What About Vitamin C Supplements?

Vitamin C supplements are easily available at pharmacies, supermarkets and health food stores. They are relatively cheap because they are easy to manufacture. While there may be some health benefits to acute dosing of vitamin C during periods of increased demand, such as when you’re sick or stressed, it’s not something you should take endlessly. Taking vitamin C supplements, especially at high doses can affect the metabolism of some medications. Aspirin, panadol, diuretics and beta blockers are among some of the medications that are influenced by vitamin C. It’s worth discussing nutrient-medicine interactions with a health practitioner if in doubt. 


Vitamin C Smoothie


  • ¼ cup papaya
  • ½ cup fresh pineapple
  • ½ cup strawberries
  • ½ cup spinach
  • 1-2 cups coconut water
  • 1 tbsp chia seeds
  • 1 squeeze honey (optional)


Blitz everything together and enjoy.

Article References

Fritz, H., Flower, G., Weeks, L., Cooley, K., Callachan, M., McGowan, J., Skidmore, B., Kirchner, L., & Seely, D. (2014). Intravenous Vitamin C and Cancer: A Systematic Review. Integrative cancer therapies, 13(4), 280–300.

Harris, H. R., Orsini, N., & Wolk, A. (2014). Vitamin C and survival among women with breast cancer: a meta-analysis. European journal of cancer (Oxford, England : 1990), 50(7), 1223–1231.

Hemilä, H., & Chalker, E. (2013). Vitamin C for preventing and treating the common cold. The Cochrane database of systematic reviews, 2013(1), CD000980.

Klimant, E., Wright, H., Rubin, D., Seely, D., & Markman, M. (2018). Intravenous vitamin C in the supportive care of cancer patients: a review and rational approach. Current oncology (Toronto, Ont.), 25(2), 139–148.

Magrì, A., Germano, G., Lorenzato, A., Lamba, S., Chilà, R., Montone, M., Amodio, V., Ceruti, T., Sassi, F., Arena, S., Abrignani, S., D'Incalci, M., Zucchetti, M., Di Nicolantonio, F., & Bardelli, A. (2020). High-dose vitamin C enhances cancer immunotherapy. Science translational medicine, 12(532), eaay8707.

Moser, M. A., & Chun, O. K. (2016). Vitamin C and Heart Health: A Review Based on Findings from Epidemiologic Studies. International journal of molecular sciences, 17(8), 1328.

Oregon State University, Linus Pauling Institute, Nutrients, Vitamin C,, viewed 9 May 2022

Pullar, J. M., Carr, A. C., & Vissers, M. (2017). The Roles of Vitamin C in Skin Health. Nutrients, 9(8), 866.

Shakoor, H., Feehan, J., Al Dhaheri, A. S., Ali, H. I., Platat, C., Ismail, L. C., Apostolopoulos, V., & Stojanovska, L. (2021). Immune-boosting role of vitamins D, C, E, zinc, selenium and omega-3 fatty acids: Could they help against COVID-19?. Maturitas, 143, 1–9.