Belief that they prevent recurrence is mistaken, say researchers

Around 40% of people who have or have had cancer take dietary supplements, and around 20% believe that this will reduce the chance of their cancer coming back, according to a new study published in the journal of the American Cancer Society, Cancer.

The authors, from University College London, say that evidence suggests this belief is mistaken. "Information about the role of supplements and the lack of evidence that they reduce cancer recurrence would be beneficial, alongside discussions about the benefits of healthy eating and physical activity," said lead author Rana Conway from University College London (UCL).

The researchers studied 1,049 adults who had been diagnosed with breast, prostate, or colorectal cancer in the United Kingdom. They completed a dietary analysis survey that included questions on supplements.

The study found that:

• 19% of participants believed that dietary supplements could reduce the risk of cancer recurrence
• Those with obesity were less likely to use dietary supplements
• Fish oils were the most commonly used dietary supplement, taken by 13% of participants