Are Vitamin C Supplements Safe And Beneficial?

Ever since its dramatic effect in preventing disease was witnessed in British sailors in the 1800s, vitamin C has often been credited with preventing all manner of illness.  At this time of year in particular, many people recommend taking high doses of vitamin C to ward off or lessen the effects of colds and flu, and some research claims it can treat cancer.  But over the years there have also been worrying reports linking vitamin C supplementation with serious side effects and even causing cancer. 

We cannot store it and so must have a regular supply, any excess being lost in the urine.  Lack of this vitamin causes breakdown of connective tissues leading to severe skin disease, bleeding and degeneration of tendons and ligaments.

In the 1800s, British sailors who had restricted diets for many months aboard ships, developed terrible skin and gum disease (known as ‘scurvy’) leading to bleeding and even death.  It was found that the disease could be completely prevented with just a daily dose of lime juice. Citrus fruits and leafy green vegetables are good sources of vitamin C, and scurvy is very rare in people with a good diet.

Proposed benefits of vitamin C

Studies have shown a link between people with high intake of vitamin C through diets high in fresh fruit and vegetables and a substantially reduced risk of developing cancer.  In the 1970s, the Nobel prize-winning scientist, Linus Pauling, claimed that vitamin C in high doses prevented colds, as well as reducing their severity and duration.

This is not far-fetched as vitamin C is known to be an anti-oxidant and these compounds are able to eliminate free radicals which are associated with causing cancer. But there seem to be as many cancer studies showing improved outcomes with vitamin C supplementation, as there are those which found no benefit. There have also been claims that vitamin C supplements can treat AIDS and polio, and also prevent heart disease and strokes. It is thought that vitamin C boosts the immune system, having an effect on white cells.

Health scares with vitamin C supplements

The toxicity of the industrial chemical chromium 6, made famous in the film Erin Brockovich, is thought to be due to an interaction with vitamin C, causing cancer-associated damage to DNA.  There is other evidence that high doses of vitamin C alone can interfere with DNA and therefore cause cancer. Some cancer specialists believe that vitamin C may actually interfere with certain cancer treatments.

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.