Vitamin supplements should not be relied on to cut people's risk of cancer, a leading expert has warned.
A fruit and vegetables-rich diet is known to cut the risk whereas there is far less confidence over the effect of supplements, Professor Martin Wiseman said.
The professor, a medical and scientific adviser for World Cancer Research Fund (WCRF), urged people to swop their supplements in favour of a healthy diet.
He said: "Many people still think they can reduce their cancer risk by taking supplements, but the evidence does not support this.
"This is why we need to get across the message that supplements should not be taken for cancer prevention and instead people should be aiming to get the nutrients they need from their diet alone.
"It is true that there is some evidence that certain supplements may protect against cancer, but we simply do not know enough to be able to confidently predict the balance of risks and benefits for the general population.
"Some people may be doing themselves more harm than good."