What Is Vitamin C?
Vitamin C (ascorbic acid) is a water-soluble antioxidant vitamin the human body cannot produce or store — unlike most mammals, humans lost the enzyme needed to synthesise it, so it must come from diet or supplements every day. Excess is simply excreted in urine, which is why very high-dose “megadosing” mostly just produces expensive urine rather than added benefit beyond a certain point.
Why Your Body Needs It
EFSA-authorised health claims for vitamin C include:
- Contributes to the normal function of the immune system
- Contributes to the normal function of the immune system during and after intense physical exercise
- Contributes to the protection of cells from oxidative stress
- Contributes to normal collagen formation for the normal function of skin, bones, cartilage, gums, teeth, and blood vessels
- Contributes to normal energy-yielding metabolism and reduction of tiredness and fatigue
- Increases iron absorption
- Contributes to normal functioning of the nervous system and normal psychological function
- Contributes to the regeneration of the reduced form of vitamin E
Signs of Vitamin C Deficiency
True deficiency (scurvy) is rare in the UK/EU but not extinct — it still turns up occasionally, usually linked to very restricted diets, alcohol dependency, or malabsorption. Milder insufficiency is more common and can show as:
- Fatigue
- Bleeding or swollen gums
- Slow wound healing
- Easy bruising
- Dry, rough skin
- Frequent infections
Who’s Most at Risk
- Smokers — smoking increases vitamin C turnover and requirements significantly
- People with very limited fruit and vegetable intake
- Older adults, particularly those living alone or with limited food access
- People with malabsorption conditions or on restrictive diets
- Heavy alcohol users
How Much Do You Need?
UK Reference Nutrient Intake is 40mg/day for adults — a relatively low bar that’s easy to reach through diet. EFSA’s Population Reference Intake is somewhat higher, at roughly 110mg/day for men and 95mg/day for women, with higher amounts recommended for smokers to offset increased turnover.
Food Sources
- Citrus fruits (oranges, lemons)
- Peppers (particularly red and yellow)
- Broccoli and Brussels sprouts
- Strawberries and kiwifruit
- Blackcurrants — among the richest natural sources available in the UK
A varied diet with regular fruit and veg easily meets the RNI; supplementation tends to matter more for smokers, restrictive dieters, or during periods of high immune demand (e.g. cold and flu season).
Choosing a Vitamin C Supplement
- Ascorbic acid is the standard, well-absorbed, and most cost-effective form
- Buffered forms (e.g. calcium ascorbate) are gentler on sensitive stomachs
- Very high doses (2,000mg+) can cause digestive upset in some people and offer diminishing returns — there’s little evidence that more is meaningfully better past typical supplemental ranges
Our pick: Solgar Vitamin C 1000mg — a straightforward, well-absorbed daily option.
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This page is for general educational purposes only and is not medical advice.
Sources & Further Reading
- NHS — Vitamin C
- NIH Office of Dietary Supplements — Vitamin C Fact Sheet
- EFSA — Health claims on vitamin C
- Linus Pauling Institute — Vitamin C Micronutrient Information
- Examine.com — Vitamin C
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