Japanese scientists have suggested that green tea may reduce risk of thyroid cancer in postmenopausal women. 

The study, which was published in the May edition of Cancer Causes Control, indicated that thyroid cancer diagnosis in postmenopausal women that consumed at least five cups of green tea daily was 53% less likely compared with those that took one or less cups a day

The 14-year study examined 48,802 men and 51,705 women aged 40 to 69 in a a self-administered questionnaire covering tea and coffee consumption. During the course of the study 26 men and 133 women were diagnosed with thyroid cancer.

The researchers found that the diminished risk of thyroid cancer diagnosis related to green tea consumption was significant in postmenopausal women but that there was no apparent correlation between the two in the general population. However, premenopausal women that drank five or more cups of green tea were found to have a 55% increased risk in being diagnosed with thyroid cancer, compared with those that drank one or fewer cups daily.