Can taking vitamin and mineral supplements help prevent cancer?
Dr Tim Perren, Consultant Oncologist, Spire Leeds Hospital
It is a common misconception that taking extra vitamins and mineral supplements in the diet may be helpful in treating or preventing a number of diseases and conditions. Regrettably there is not any scientifically robust evidence available that indicates this is necessarily the case.
Vitamins and minerals have a series of extremely important functions in the body and there is no doubt that an unhealthy diet which is likely to contain excessive amounts of unhealthy fat and salt, and which may also be deficient in a range vitamins and minerals can cause a spectrum of medical conditions and illness including cancer.
The body needs to have adequate amounts of vitamins and minerals if it is going to work properly. People who are deficient in these substances may become unwell in a variety of ways. However, patients who take a normal diet and who have normal absorption will have adequate amounts of vitamins and minerals in their body and probably do not benefit from taking excessive levels of these substances. It is however recommended that pregnant women should routinely take folic acid in order to protect the developing baby. It is also recommended that children who do not eat a healthy well balanced diet should take a multivitamin preparation.
Some "natural substances" that are derived from plants are extremely powerful medicines in their own right, and could well be harmful if taken to excess. Good examples are digitalis, which is derived from foxgloves, and which is a very powerful heart medication, aspirin is also derived from a plant.
Even some chemotherapy drugs, in common use as anti cancer treatment are derived from plants; good examples are vincristine which is derived from the periwinkle, and the taxane drugs which are derived from the yew tree. Substances such as Saint John's Wort can also be harmful since they may interfere with the absorption and metabolism of a number of important drugs.
Cancer Research UK are helping to fund a huge European Study called EPIC which will examine in a robust scientific way the relationship between diet and cancer and which will also look at levels of various nutrients. The results of this study will not be ready for at least 10 years. In the meantime Cancer Research UK recommend a healthy, balanced diet that is high in
fibre, fruit and vegetables, and low in red and processed meat and salt.
Patients should always consult their own general practitioner before starting to take alternative medications or large doses of vitamin or mineral supplements.