Flaxseed 'blocks prostate cancer'

However, the amount given to the mice was far too high to be a realistic prospect in a human diet.

It also contains large amounts of dietary fibre and a chemical called lignan which controls the metabolism of both oestrogen and testosterone.

This is not the first study to suggest that flaxseed could be beneficial against prostate cancer.

Research published last year found that lignans taken from flaxseed were able to inhibit the growth of prostate cancer cells in the laboratory.

Another found that a low-fat diet, supplemented with flaxseed, was linked to slower tumour growth.

In the latest study, 135 mice genetically engineered to develop prostate cancer were split into two groups.

Half got a conventional diet, half a diet rich in flaxseed.

Tumours in the conventional diet group were twice the size roughly of those in the flaxseed group, and two mice in the flaxseed group did not get cancer at all.

Cause for optimism

Dr Wendy Demark-Wahnefried, who led the study, said: "We are cautiously optimistic about these findings.

"The amount of flaxseed given to each mouse was 5% of its total food intake, which would be a very difficult amount for humans to eat, but it does signal that we are on the right track and need to continue research in this area."

Another researcher, Dr Xu Lin, said: "So far we have observed the suppression of prostate cancer in humans, mice and at the cellular level.

"It's not a fluke or a coincidence. It's an encouraging line of research."

The latest study was published in the journal Urology.