Vitamin C (ascorbate)

Most UK labs print about 26 to 85 umol/L for a healthy diet, describe below about 11 as depleted, and note that the value is very sensitive to sample handling and to recent intake.

Vitamin C, ascorbic acid, is a water-soluble vitamin from fruit and vegetables that the body cannot make. It is needed to build collagen, the scaffolding of skin, gums, blood vessels and bone, to absorb iron, and as an antioxidant. Stores last only a few weeks, so the blood level reflects recent intake more than long-term status.

It is requested when scurvy is a possibility, for example with bleeding gums, easy bruising, poor wound healing or unexplained anaemia in someone with a very restricted diet, an eating disorder, heavy alcohol use, or on dialysis. It is also on some private nutrition panels.

• Vitamin C supplements, which raise it within hours
• A diet rich in fruit and vegetables
• Intravenous vitamin C

• A diet with little fruit or vegetables over a few weeks, including eating disorders and very restricted diets
• Smoking, which uses it up faster
• Heavy alcohol use
• Any inflammation, infection, surgery or serious illness
• Dialysis and some digestive conditions
• Pregnancy and breastfeeding, slightly

• It breaks down in the tube within an hour unless the sample is chilled, protected from light and processed straight away, so a low value can be a handling problem
• A supplement or a glass of orange juice before the test raises it
• Smokers and people with a recent infection run lower

Fasting, protected from light, and processed within an hour or so; many labs need special handling, so it is often only done in hospital. Ideally taken before any supplement is started.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.