Are Vitamin C Supplements Needed?

Before considering vitamin C supplements ensure that you maximize your dietary source by eating lots of fresh fruit and vegetables.  It is believed that the cancer prevention seen in people with diets high in vitamin C may be due to other nutrients in fresh fruit and vegetables, not found in supplements.  These may be fibre or other plant ingredients (phytochemicals) such as the flavones and carotenoids found in fruit and vegetables.

Also, it is thought by some that naturally-derived vitamin C is more effective than synthetic supplements.  But dietary vitamin C may not be enough. 

Some studies have found a high proportion of cancer victims to be deficient in vitamin C.

Vitamin C and cancer

The treatment of cancer and other diseases is too serious a matter to consider tackling yourself. So seek advice from a doctor before considering vitamin supplementation.  Also, most of the benefits in cancer treatment have been seen with the use of particularly large doses of intravenously-administered vitamin C, which is not something you can try at home.

Vitamin C for colds and flu

Evidence seems particularly strong for people who exercise heavily or in physically stressful environments (like extreme cold).

How much should be taken?

Taking ‘mega-doses’ of more than 1,000mg (1g) a day is still very controversial and not currently recommended by the medical profession.  The upper limit for human consumption is officially 2g. Taking too much vitamin C commonly causes stomach upset such as diarrhoea, pain and cramps. It can also lead to too much iron being absorbed from the diet, which may cause problems for some people.

The World Health Organisation recommends that 45mg of vitamin C per day is needed for maintenance of health, but this is only the minimum required to prevent scurvy.  The recommended daily intake in the US (from the national Institute of Medicine) is 75mg for women and 90mg for men, with an extra 35mg per day advised for smokers.  To give you an idea of what this entails, 8oz fresh orange juice contains 120mg and half a cup of red pepper has 140mg of vitamin C.

Slow release or time release formulations deliver the dose more slowly and may lead to better absorption. Some people particularly recommend taking a modest vitamin C supplement during the cold and flu season, with or without zinc, which is also alleged to boost the immune system.