For cancer prevention, don't rely on supplements

Eat a healthy diet rather than relying on supplements to protect against cancer

Despite the promises made by some manufacturers, evidence to date is inconsistent. Some studies suggest that high-dose supplements can actually be harmful. As the effect of supplements on cancer risk is unclear, we advise against taking supplements to reduce your cancer risk – instead, aim to meet your nutritional needs by eating a varied, healthy, balanced diet.

Whole foods provide more than just vitamins and minerals. For example they contain fibre, which reduces the risk of bowel cancer. For this reason supplements shouldn't be used as an alternative to eating well.

What are supplements?

Supplements contain: vitamins; minerals; other components of foods such as lycopene, found in tomatoes; herbs; and plant materials such as ginseng, garlic and green tea, sometimes in high doses. Supplements can be in pill, capsule, powder or liquid form.

Who may benefit?

Most people can meet their nutritional needs by eating a healthy, balanced diet. However, some groups may benefit from taking supplements, such as:

  • Frail, older people with a poor appetite
  • Women of childbearing age and new mothers
  • Children under the age of five
  • People with darker skin and those who are not exposed to much sun such as housebound people or those who cover their skin
  • People with bowel diseases, those who are being treated for cancer or who have survived cancer may not be able to absorb enough nutrients from their diet or to eat a normal diet, so may also benefit

In such cases, a doctor, dietitian or specialist nurse will be able to provide advice.