CAFFEINE has been blamed for everything from genetic abnormalities to miscarriages. But researchers now claim the much-demonised substance may fight cancer.

After studying more than 80,000 women, US and Australian experts found foods containing caffeine - such as coffee, tea, cola and chocolate - may reduce the risk of ovarian cancer, the sixth-most common cause of cancer deaths among Australian women.

According to Shelley Tworoger of Harvard University in Boston and her colleagues - including medical epidemiologist Dorota Gertig of the University of Melbourne and Victorian Cytology Service - decaffeinated coffee showed no health benefit at all.

For reasons they cannot yet explain, the group also found the beneficial effect of caffeine was strongest for women who had never used oral contraceptives or postmenopausal replacement hormones.
 

Oncologist Ian Olver, head of Cancer Council Australia, said the finding was interesting and based on a very comprehensive study.

"It's well worth looking into further," Professor Olver said. "We don't know very much about modifiable factors for ovarian cancer."

Assistant Professor Tworoger, Associate Professor Gertig and their team looked at possible associations between ovarian cancer and lifestyle behaviours such as smoking and alcohol, and caffeine consumption.

They analysed data from the Nurses' Health Study, an ongoing assessment of the wellbeing of 212,701 female registered nurses that began in 1976 when the nurses were aged 30-35.

Every two years, researchers at Boston's Brigham and Women's Hospital checked up on the surviving women. After studying the nurses' history, Professor Tworoger and Professor Gertig's group found only a very small association between smoking and mucinous tumours, a rare form of ovarian cancer. They found no connection between alcohol consumption and ovarian cancer.

Because the work is so preliminary, Professor Olver agreed with the team's conclusion that their findings warranted further study.

In the meantime, Professor Olver said coffee and chocolate couldn't hurt and might even help.

"My standard advice is everything in moderation," he said.