The tomato has been altered to boost its production of lycopene, a natural ingredient which has been shown to reduce significantly the risk of men developing the cancer.
The research marks a new era in the genetic enhancement of food. Until now changes have concentrated on improving the crop yields or the shelf-life of supermarket products.
A "virility" tomato is one of the first in a new line of genetically engineered products which are aimed at improving the extra nutritional content of a wide variety of foods. The tomato is generating intense interest from biotechnology companies which want to sell lycopene-enriched products.
Tomatoes have the highest levels of lycopene of any fruit or vegetable and could account for the low incidence of prostate cancer in some Mediterranean countries, where older men are renowned for their continued interest in love-making.
Several studies have shown that men who eat between five and 10 servings of tomato a week decrease their risk of developing prostate cancer by nearly a half.
Levels of lycopene in the body are highest in the testes, prostate and adrenal glands, which are intimately involved with generating the hormones that are necessary for sexual performance.
Zeneca, the British biotechnology company, is running a lycopene research project aimed at boosting the naturally high levels of the substance in tomatoes.
Camilla Beech, a Zeneca executive, said the company's scientists have identified many of the genes involved in the production of lycopene in tomatoes and are developing ways of increasing its concentration. "We are trying to get the plant to overproduce lycopene in the tomato fruit. We have identified the genes and created transgenic plants," she said.
Beech said it was too early to say whether Zeneca will market the tomato as a "virility product" given that it will take at least two years for it to receive the approval of regulatory bodies. "We would have to see what the market potential is," she said.
Jack Winkler, an independent policy analyst on the health aspects of food, said it might be easier for Zeneca to sell the tomato as a virility booster than as a product for preventing prostate cancer.
"As the regulations stand it is more permissible to say something maintains and enhances health than it is to say it prevents disease. I think this tomato is more likely to be sold as something that maintains natural powers than something which can help to avoid cancer," Winkler said.
The creation of new foods with medicinal properties is not restricted to tomatoes. Many companies are experimenting with adding extra calcium to products such as chewing gum to prevent osteoporosis in older women.
Healthy shoppers in America can buy eggs from hens fed on fish oil: the eggs are enhanced with antioxidants, vitamin E and essential fatty acids for guarding against heart disease and cancer.
Gerbl=E9, the French confectionary company, sells a chocolate called Barre Memoire that is enriched with a substance believed to help improve the memory; in Britain, Allied Bakeries has recently launched Burgen bread with added phyto-oestrogens to help menopausal women cope with hot flushes.