Vitamin C (Ascorbic Acid)

Vitamin C is important for the production of collagen, a protein found in skin, cartilage and bone, which is involved in the healing process. Vitamin C is required for the structure and functioning of the brain and the blood vessels. Vitamin C also acts as a powerful antioxidant by protecting cells from damage by oxygen.

Recommended daily intakes (RDI) for Vitamin C (mg/day)

 

Age (years)

 

19+ years

Women

30

Men

40

Fewer than 1% of New Zealanders have an inadequate intake of Vitamin C. Smokers are recommended to consume up to an extra 80mg of Vitamin C per day, due to the stress that cigarette smoking puts on the body.

There is currently some debate over the Recommended Daily Intakes (RDIs) for Vitamin C. The New Zealand RD’s are set to prevent the onset of scurvy. It has been suggested that the RD’s should be increased to cover disease prevention and antioxidant activity.

Diets containing more than 200 mg of Vitamin C per day have been associated with a lower risk of cancer. Whether this is due to Vitamin C alone or to a combination of components found in foods also containing Vitamin C is still to be established. However, no association has yet been found between a decrease in cancer risk and Vitamin C supplements.

Eating a diet rich in fruit and vegetables provides a substantial intake of Vitamin C per day, approximately 50-60 mg. Supplement safe limits of Vitamin C are 250-500 mg/day, but many supplements contain Vitamin C at levels above this. An individual needs to consider their everyday dietary intake of Vitamin C before adding a supplement to their daily routine. Consuming Vitamin C in excess of 500 mg per day is wasteful as it is excreted into the urine.

Vitamin C deficiency

Severe cases of Vitamin C deficiency can cause scurvy, although in today's modern world this disease is rarely seen. The symptoms of scurvy are bleeding gums, poor wound healing and damage to bones and muscles.

Vitamin C toxicity

Too much Vitamin C can lead to migraines and diarrhoea. Individuals consuming a balanced diet receive ample Vitamin C from fruit and vegetables, which is a safer option than risking excess intakes from supplements.

Food sources of Vitamin C

Vitamin C present in many fruits and vegetables is unstable and easily destroyed. 50-80% of Vitamin C is lost from vegetables when boiled, so it is advisable to cook vegetables in minimal water or in the microwave. Chopping and dicing of fruit and vegetables also causes large losses of Vitamin C because it increases the surface area of the food.

Vitamin C cannot be manufactured or stored in the body so we need to ensure an adequate dose from our daily diet by making sensible food choices.
The principle sources of Vitamin C in the New Zealand diet are vegetables, non-alcoholic beverages and fruits. Levels of Vitamin C can vary greatly between fruits and vegetables. Some good sources of Vitamin C are strawberries, kiwi fruit, oranges, potatoes, broccoli, spinach and kumara. It is recommended that New Zealanders should eat at least three servings of vegetables and two servings of fruit every day. Dried fruit are not a good source of Vitamin C due to the processing involved in the production of dried fruit.

Foods containing Vitamin C also assist in the absorption of non-haem iron when consumed during the same meal.