What is vitamin C?
Essential for growth and supporting the immune system – learn more about this essential vitamin. Discover which foods are good sources and our top recipe recommendations
What is vitamin C?
Vitamin C, or ascorbic acid, is a water-soluble vitamin. The human body is unable to synthesise the vitamin or store it in large amounts. As a result, when daily recommendations are met, any excess is excreted in the urine. Vitamin C is absorbed well from the food we eat – this absorption occurs in the small bowel.
Why do we need vitamin C?
Vitamin C has many important roles in the body. It is needed for growth and repair, and it plays a central role in supporting the immune system. It also has antioxidant properties which means it fights free radicals, which are derivates of oxygen that attack the body’s cells.
Vitamin C is also involved in the synthesis of collagen and carnitine and also increases the gastrointestinal absorption of non-heme iron. Studies have also suggested that vitamin C may play a role in the body's ability to deal with some types of cancer-causing particles, which may be found in the body.
Consuming very low levels of vitamin C for three months or more can result in a condition called scurvy – visit the NHS website to find out more.
How much vitamin C do we need?
In the UK, the daily requirements for ascorbic acid are 40 mg per day for adults, with an increase in pregnancy to 50 mg per day for the last trimester, and during lactation to 70 mg per day.
You should be able to get all the vitamin C you need from your daily diet.
What are the effects of consuming too much vitamin C?
It’s difficult to consume too much vitamin C because any excess is excreted in the urine. Excess amounts tend to happen when large doses of supplements are taken – if too much vitamin C is consumed this may cause stomach pain, flatulence and diarrhoea.
Those prone to renal stones (calcium oxalate) should be mindful of taking high-dose vitamin C supplements because research suggests there is an increase in urinary oxalate excretion for every 1000mg of ascorbic acid consumed.
Speak to your GP if you are concerned about deficiencies or are considering taking dietary supplements.
Can vitamin C help prevent or shorten colds?
There is insufficient evidence that vitamin C helps to prevent or shorten colds.
Which foods are good sources of vitamin C?
Fruit and vegetables are the best source of vitamin C and these can be fresh, frozen or tinned. Guava, papaya, green and red peppers, broccoli, kiwi fruit, oranges, blackcurrants and strawberries tend to be high in vitamin C, however all fruit and vegetables contain it – another good reason to eat a rainbow!
Fortified breakfast cereals are also a good source. The vitamin C content of many foods may be reduced by prolonged storage and cooking as ascorbic acid is water soluble and is destroyed by heat. Steaming or microwaving may help to prevent cooking losses.
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This article was last reviewed on 28 June 2022 by Kerry Torrens.
Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food. Find her on Instagram at @kerry_torrens_nutrition_
Emer Delaney BSc (Hons), RD has an honours degree in Human Nutrition and Dietetics from the University of Ulster. She has worked as a dietitian in some of London's top teaching hospitals and is currently based in Chelsea.
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