An artificial version of the pigment that gives tomatoes their colouring is being tested on prostate cancer patients after promising animal trials.
Tomatoes contain lycopene
Researchers at the Erasmus Medical Centre in Rotterdam, Holland, had found synthetic lycopene slowed the growth of human prostate tumours in mice.
Lycopene has already been linked with a reducing the risk of prostate cancer.
It is now the most common form of the disease in men, affecting around 21,300 men in Britain annually.
Around 10,000 men a year die from the disease.
In their mice research, the Dutch scientists found a low dose of the synthetic lycopene slowed the growth of human prostate tumours implanted in the mice by over 50% by day 42 of the study, compared to mice who had not had the treatment.
And when the lycopene was combined with vitamin E, it reduced the growth of tumours by up to 73%.
The researchers found that levels of PSA (prostate specific antigen) matched the growth of the tumour, meaning that can be used to monitor the treatment's effects in men.
Dr Jacqueline Limpens, from the Erasmus Medical Centre presented the team's findings to a cancer symposium in Geneva.
She said: "What was particularly marked was that it was the low dose of both lycopene and vitamin E that was the most effective, demonstrating that 'more does not necessarily equal better'.
"Many pharmacological agents and natural compounds follow a bell-shaped dose
response curve, which means that very low or high doses may not work and that
there is an optimal dose between the two extremes."
The product being used in the research is a lycopene supplement called LycoVit.
Dr Limpens said more research was needed before doctors could say if a combined lycopene and vitamin E treatment could be given to healthy men to prevent them developing prostate cancer.
But she said her team's findings tied in with other studies suggesting that lycopene and vitamin E could protect against the disease.
"Therefore we would certainly recommend that all men regularly eat lycopene
and vitamin E-rich foods - for example, all kinds of processed tomato products,
papayas, pink grapefruit and watermelon, wheat germs, whole grains, mangoes,
leafy green vegetables, nuts and olive oils," she said.
"Of course, this needs to be part of an all-round healthy lifestyle and diet
with plenty of vegetables and other healthy foods."
Dr Chris Hiley, head of policy and research at the Prostate Cancer Charity, told BBC News Online: "We welcome the promising results of this study.
"We're still a way off firm conclusions until lycopene and vitamin E are tested in men with prostate cancer.
"In the mean time, our advice to men remains the same - maintain a healthy diet containing lycopene and vitamin E rich foods listed.
"This is a practical approach that men with prostate cancer already, or those concerned about developing it, can easily adopt."