Vitamin C

Background

Vitamin C, aka ascorbic acid, is a water soluble vitamin. It cannot be made in the body and therefore is acquired purely from diet. It is mostly known for its antioxidant ability. It also aids in collagen production, white blood cell production, some enzyme reactions and many other examples¹.

Why do you need it?

A lack of vitamin C in the diet can cause the disease scurvy, which is rare in developed countries. However, many studies have shown the possibility of a dose much higher than that to avoid scurvy, can help us to avoid many more diseases, such as cancer and cardiovascular diseases^2,3. Although it is hard to experimentally link vitamin C to cancer directly, many studies have shown vitamin C reduces oxidative stress, which has been linked to cancer ^4-7. 

Article on antioxidants, free radicals and oxidative stress coming soon!

Vitamin C and immunity

Whether vitamin C helps with colds is long disputed. Some studies show there may be a reduction in cold incidence when vitamin C was taken before onset of any cold symptoms. However, Studies provide little evidence to show the benefits of vitamin C when supplementation starts after onset of symptoms⁸. So don't wait until you have a cold!

Vitamin C aids in the body’s innate immune defences, by supporting the physical barriers that are your skin cell membranes, and also in the adaptive immune system, which include the immune cells and responses that fight pathogens directly⁹. Vitamin C has been shown to accumulate in some immune system cells, and help these cells to follow the chemical signals left by pathogens¹⁰.

Vitamin C has also been shown to aid in the production and proliferation of some immune cells, and has shown evidence of treating and preventing respiratory and systemic infections. The levels of vitamin C required for prevention of such infections was shown to be several times higher than the recommended daily allowance, meaning supplementation could be required¹¹.

WHICH FOODS ARE HIGH IN VITAMIN C?

1 (119 g) medium red bell pepper - 380% of your daily intake

1 serving (148 g) broccoli -  330% of your daily intake

100 g of raw kale - 300% of your daily intake

1 (131 g) orange - 174% of your daily intake

1 (45 g) red chilli pepper - 162% of your daily intake

1 (69 g) kiwi - 160% of your daily intake

Which potency is right for me?

The RDA for vitamin C is 40 mg, but as it says above, there may be benefits of much larger doses. Especially amongst smokers and those who don't regularly eat their 5 a day. If you think you get a lot of free radical exposure, e.g. from the sun or smoking, or you don't get a lot of vegetables, go for the 1000 mg. Otherwise, 500 mg should give you the boost you need. If in any doubt, seek professional medical advice.

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Sources:

1. Office of Dietary Supplements Factsheet, 2019
2. Vitamin C and Heart Health: A Review Based on Findings from Epidemiologic Studies. (Moser, 2016)
3. Vitamin C and cardiovascular disease: a review. (Simon, 1992)
4. Vitamin C and cancer prevention: the epidemiologic evidence. (Block, 1991)
5. Vitamin C Induces the Reduction of Oxidative Stress and Paradoxically Stimulates the Apoptotic Gene Expression in Extravillous Trophoblasts Derived From First-Trimester Tissue. (Kawashima, 2015)
6. Oxidative stress, inflammation, and cancer: How are they linked? (Reuter, 2010)
7. The role of oxidative stress in carcinogenesis. (2004, Klaunig)
8. Vitamin C for Preventing and Treating the Common Cold. (Douglas, 2005)
9. Selected vitamins and trace elements support immune function by strengthening epithelial barriers and cellular and humoral immune responses. (Maggini, 2007)
10. Vitamin C and Immune Function. (Carr, 2017)
11. Determination of optimal vitamin C requirements in humans. (Levine, 1995)