Vitamin C

What it does

Vitamin C, or ascorbic acid, is essential for making collagen, the structural protein that holds the body together. Collagen gives strength and flexibility to skin, blood vessels, tendons, cartilage, bone and gums, and it is the framework on which wounds heal. Vitamin C is a required helper for the enzymes that build stable collagen, which is why a severe deficiency (scurvy) causes bleeding gums, poor wound healing and fragile blood vessels.

It is also one of the body's key water-soluble antioxidants, mopping up reactive molecules produced during normal metabolism and helping to regenerate other antioxidants such as vitamin E. Through this it helps protect cells from oxidative damage and supports the immune system, contributing to the normal function of white blood cells and the skin's role as a barrier against infection.

Vitamin C has a very practical everyday role too: it dramatically improves the absorption of non-haem iron (the form found in plant foods) from the same meal, which is useful for people relying on vegetables and pulses for iron. Humans cannot make vitamin C, so a regular dietary supply is essential. It is abundant in citrus fruit, berries, peppers, broccoli and potatoes, but it is fragile — easily destroyed by heat, light and prolonged cooking in water.