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An Australian study has shown women who drink at least four cups of tea per day have a reduced risk of ovarian cancer.

The research is published in the journal Cancer Causes Control.

The Queensland Institute of Medical Research (QIMR) studied the food and lifestyle habits of about 2700 women, half of whom had a history of ovarian cancer.

'The main finding of the study was that women who drank four or more cups of tea per day - and that was any type of tea, black, green or herbal - may have a reduced risk of ovarian cancer by 30 per cent,' said QIMR's Dr Christina Nagle.

Dr Nagle said the study found tea was broadly beneficial, and there was no added benefit from drinking green tea despite it being promoted as the 'healthiest kind of tea'.

She said that it was not fully understood how tea worked to reduce a person's cancer risk, and several clinical trials were under way in the US to find what was responsible.

'Tea is rich in antioxidants, which are an important part of a healthy diet,' Dr Nagle said.

'We assume it is the antioxidants in tea that are beneficial in terms of reducing risk of cancer.'

Despite the positive results Dr Nagle said it was too early to place tea consumption alongside smoking and sun exposure, two key factors in a person's overall risk of developing cancer.

Studies on animals have suggested tea could inhibit the growth of ovarian cancer cells, she said, though experiments designed to test the effect on humans had produced mixed results.

'Many studies show a beneficial effect of drinking tea, in terms of reducing the risk of different types of cancer,' Dr Nagle said.

'But it seems to be that in studies in humans it is inconsistent ... I think the jury is still out.'

Almost 1200 Australian women are diagnosed with ovarian cancer every year, while the disease claims about 800 lives.