Salads could become more colorful - and healthier -thank to unusually red tomatoes that could help to protect people against cancer and heart disease. Peter Bramley and his colleagues at Royal Holloway College , London , have genetically engineered tomatoes so that they contain unusually large amounts of lycopene and B -carotene. These compound are among a group of chemicals called antioxidantsthat are thought to mop up highly reactive compounds called free radicals inside cells. Left at large , free radicals can damage DNA , possibly leading to cancer-causing mutations. Free radicalsare also believed to play a role in the development of heart disease, triggering reactions that lead arteries to fur up with fatty deposits.