Vitamin C

The Science

Vitamin C

Vitamin C, or ascorbic acid, is a water-soluble vitamin well known for its role in supporting a healthy immune system. Vitamin C contributes to immune defence by supporting various cellular functions of both the innate and adaptive immune system (see the Scientific References below).

Because our bodies cannot make vitamin C, it must come from the foods (and supplements) that we eat every day.

Vitamin C

Occurrence in Food & Supplements

“Food of plant origin, particularly citrus and soft fruits and leafy green vegetables, are major sources of vitamin C. Kidney and liver are good animal-derived sources of vitamin C. Vitamin C is readily lost during cooking, due to oxidation. Vitamin C is present in numerous dietary supplements.” (EVM 2003)

Absorption & Bioavailability

“Gastrointestinal absorption of vitamin C is efficient and occurs in the small intestine via a saturable active transport mechanism. Absorption efficiency of low oral doses of vitamin C (4-64 mg) may be as high as 98%, but decreases with increasing doses of the vitamin.” (EVM 2003)

Safe Daily Level

“A supplemental dose of 1000 mg/day supplement would not be expected to have any significant adverse effects.” (EVM 2003)

Vitamin C Health Claims

Vitamin C…

  • contributes to the normal function of the immune system.
  • contributes to the protection of cells from oxidative stress.
  • contributes to normal energy-yielding metabolism.
  • contributes to normal collagen formation for the normal function of skin, blood vessels, cartilage, bones, teeth and gums.
  • contributes to normal functioning of the nervous system.
  • contributes to normal psychological function.
  • contributes to the reduction of tiredness and fatigue.
  • increases iron absorption.
  • contributes to the regeneration of the reduced form of vitamin E.

Further Information

Vitamin C

As can be seen above, Vitamin C provides a wide range of beneficial effects, but it is best known for its antioxidant and immune-boosting effects, and in particular, helping us get over colds faster. So, vitamin C may not always prevent us from getting sick, but it does reduce the average duration of cold symptoms (see reference at bottom of page).

Vitamin C has several vital roles within the optimal functioning of the human body, one of which is its ability to maintain the normal function of the immune system during and after intense physical exercise. This supports the normal functioning of the immune system contributing to a reduction in tiredness and fatigue. It also works in conjunction with Iron, particularly non-haem Iron, to increase the absorption levels and prevent Iron deficiency anaemia.

Vitamin C has also been found to help with normal physiological function, prompting normal energy metabolism and protecting cells from oxidative stress – all three functions also work to improve depleted energy levels. Another important role of this antioxidant is to contribute to the normal functioning of the nervous system, as well as regeneration of the reduced form of Vitamin E – another antioxidant. Lastly, the vitamin benefits the formation of collagen and aids the functioning of several physiological elements, including blood vessels, bones, cartilage, gums, skin and teeth.

Scientific References

“Vitamin C has consistently decreased the duration of cold episodes and the severity of symptoms.”

Hemilä, H. (1992). Vitamin C and the common cold. British Journal of Nutrition, 67(1), 3-16. doi:10.1079/BJN19920004

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“Supplementation with vitamin C appears to be able to both prevent and treat respiratory and systemic infections”

Carr AC, Maggini S. Vitamin C and Immune Function. Nutrients. 2017 Nov 3;9(11):1211. doi: 10.3390/nu9111211. PMID: 29099763; PMCID: PMC5707683.

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