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. It is absorbed well from the food we eat – this occurs in the small bowel.
Why do we need vitamin C?
Vitamin C has many important roles in the body. It is required for growth and repair of cells and it plays a significant role in supporting the immune system. It is also an antioxidant and 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-haem 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?
Daily UK recommendations 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 that you need from your daily diet.
What are the effects of consuming too much vitamin C?
As any excess is excreted in the urine, it is very difficult to consume too much vitamin C from the diet. This tends to happen when large doses of supplements are taken and may cause stomach pain, flatulence and diarrhoea.
Individuals with calcium oxalate renal stones need to be mindful of taking high dose vitamin C supplements as research suggests there is an increase in urinary oxalate excretion per 1000mg per day ascorbic acid.
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 conclusive 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.
Recipes that are rich in vitamin C
More on vitamins and minerals
This article was published on 25th June 2019.
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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