Vitamin C, also called ascorbic acid, is a water-soluble vitamin found in many fruit and vegetables. Humans cannot make it, so it has to come from food or supplements. It is needed for collagen formation, normal wound healing, immune function, iron absorption, and protection of cells from oxidative damage.
Because vitamin C is water-soluble, the body does not store large reserves. Regular intake from food is therefore more useful than occasional large doses.
Functions
Vitamin C helps several normal body processes:
- Collagen formation: collagen is needed in skin, gums, blood vessels, bone, cartilage, and connective tissue.
- Wound healing: collagen production is part of normal repair after injury.
- Iron absorption: vitamin C improves absorption of non-haem iron from plant foods.
- Antioxidant activity: vitamin C helps limit oxidative damage in cells.
- Immune function: it supports several immune cell functions, although it is not a cure for infections.
- Enzyme reactions: vitamin C is involved in making some hormones and neurotransmitters.
Food Sources
Good food sources include:
- Citrus fruit such as oranges and grapefruit.
- Strawberries and blackcurrants.
- Kiwi fruit.
- Peppers.
- Broccoli.
- Brussels sprouts.
- Potatoes.
- Leafy green vegetables.
Vitamin C can be reduced by prolonged storage, boiling, or repeated reheating. Steaming, microwaving, or eating some fruit and vegetables raw can preserve more of it.
Intake
UK NHS guidance says adults aged 19 to 64 need 40 mg of vitamin C a day and should normally be able to get that amount from a varied diet. U.S. NIH guidance uses different recommended amounts, including 90 mg a day for adult men and 75 mg a day for adult women, with higher suggested intake for smokers.
The difference between national figures reflects different reference systems. It does not mean that one orange or one supplement dose has the same meaning in every diet.
Deficiency
Severe vitamin C deficiency causes scurvy. Features can include tiredness, swollen or bleeding gums, easy bruising, poor wound healing, joint pain, and anaemia. Deficiency is uncommon in people with a varied diet, but risk is higher with very limited food intake, eating disorders, alcohol dependence, smoking, some gastrointestinal conditions, and severe food insecurity.
Milder low intake may not cause obvious symptoms at first. Diet history, symptoms, and sometimes blood tests can be used to assess suspected deficiency.
Supplements
Most people can meet their needs from food. Supplements may be useful when diet is limited or deficiency risk is high, but high-dose products are often unnecessary.
Large doses can cause diarrhoea, nausea, stomach cramps, and other digestive symptoms. People with kidney stone risk, kidney disease, iron overload conditions such as haemochromatosis, or complex medication regimens may need extra caution with high-dose supplements.
Common Claims
Vitamin C is often marketed for colds, immunity, skin, tiredness, and general health. Evidence is mixed. Regular vitamin C supplements may slightly shorten cold duration in some studies, but taking vitamin C after cold symptoms start has not consistently shown the same benefit. Claims about preventing cancer, heart disease, or infections should be read carefully because diet, dose, population, and study type matter.
Food sources are usually the simplest route because they provide fibre, potassium, folate, and other nutrients alongside vitamin C.
See Also
References
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