Green tea does not offer any protection against breast cancer, the results of a new study indicate.

According to Japanese researchers, previous animal studies have suggested that green tea may produce beneficial effects against the disease, however results from human studies have been inconclusive. They set out to investigate the issue further.

Some 2,400 new cases of breast cancer are diagnosed in Ireland every year.

The researchers looked at around 54,000 women who drank varying amounts of green tea - from those who drank less than one cup per week to those who drank 10 or more cups per day. Altoegther, around 12% of the women drank less than one cup per week, while 27% drank five or more cups per day.

Tea intake was assessed by questionnaire, once at the beginning of the study and then again five years later. Cancer incidence meanwhile was assessed by notification from major local hospitals in the study area and data linkage with population-based cancer registries.

The study found no overall association between green tea intake and the risk of breast cancer.

"Drinking green tea as a beverage is unlikely to reduce the risk of breast cancer regardless of green tea type and number of cups," said researcher, Motoki Iwasaki, from the National Cancer Center in Tokyo.

Details of these findings are published in the journal, Breast Cancer Research.