Vitamin C

How much do you need daily?

Adults need 40 milligrams of vitamin C per day. Vitamin C can't be stored in the body, so you need it in your diet every day. 

Are we getting enough?

The 2014 National Diet and Nutrition Survey found that daily average intakes of vitamin C from food sources were well above recommended levels for all ages. The number of people with very low intakes was less than one per cent. 

Why do we need it?

Vitamin C (also known as ascorbic acid) is necessary for the growth and repair of all the tissues in the human body. It helps make collagen, an important protein which is one of the basic components in the skin, cartilage, tendons, ligaments and blood vessels. Vitamin C is also needed for wound healing and for healthy bones and teeth. On top of that, it helps the body absorb iron from diet.

Vitamin C is an antioxidant, which means it helps prevent our DNA from the damage caused by free radicals – dangerous metabolism by-products.

It’s easy to get enough vitamin C from a healthy diet but if you eat mostly processed food, your levels might be low. Smoking cigarettes also lowers the amount of vitamin C in the body, so smokers need to have higher intakes. It’s best to get vitamin C from foods, as a supplement might not have the same effect and vitamin C rich foods tend to have multiple health benefits. Vitamin C is sensitive to heat and light so it’s best to eat vitamin C foods raw or lightly cooked.  

Water-soluble nutrients like vitamin C may be lost during cooking. For example, raw broccoli contains 79 milligrams per 100 grams, steamed broccoli contains 60 milligrams and boiled, just 44 milligrams. So boiling broccoli may cause losses of over a third of its vitamin C content and microwaved or stir-fried broccoli, up to a quarter. Steaming does not cause such significant losses of vitamin C in broccoli. Cooking can remove up to two-thirds of the vitamin C in fresh spinach and canned peas and carrots may lose 85 to 95 per cent of their vitamin C. Depending on the method used, loss of vitamin C during cooking typically ranges from 15 to 55 per cent. Try to avoid boiling vegetables, lightly steam them and just gently wilt leaves like spinach and chard.

Cooking isn’t all bad, it boosts the level of some nutrients including lycopene in tomatoes. Lycopene may be an even more potent antioxidant than vitamin C. A mixture of fresh and lightly cooked vegetables will provide all the vitamin C you need. 

Vitamin C levels are often are higher in frozen foods compared with fresh produce, probably because vitamin C is lost during storage and transport of fresh produce.

If you take large amounts of vitamin C – more than 1,000 milligrams daily – it can cause stomach pain, diarrhoea and/or flatulence. Contrary to popular belief, vitamin C supplements don’t help prevent colds but a healthy diet with vitamin C rich foods can help boost your immune system. 

Do I need a supplement?

No, a healthy vegan diet containing the above foods on a daily basis will cover your needs.

The best plant sources

The best plant sources of vitamin C include blackcurrants, pepper (red and green), kale, papaya, spring greens, cranberry juice, strawberries, Brussels sprouts, broccoli, cabbage, mange-tout, cantaloupe melon, kiwi, grapefruit, mango, oranges, watercress, raspberries, tomatoes, cauliflower, potatoes, pineapple and spinach. Parsley is generally only used sparingly in foods but is a rich source of vitamin C (190 milligrams per 100 grams) so just a couple of sprigs can provide a great boost.

Surprisingly, blueberries, apples, cucumber, grapes and lettuce all contain relatively low levels (six milligrams or less per 100 grams) compared to the above fruit and vegetables. Meat, fish, poultry, eggs and dairy products and grains are not considered good sources as they contain either very little or no vitamin .

Signs of deficiency

dry and splitting hair, gingivitis (inflammation of the gums) and bleeding gums, dry and scaly skin, slow wound-healing, easy bruising, nosebleeds, greater susceptibility to infection; a severe form of vitamin C deficiency is known as scurvy.