Green tea can help prevent glaucoma and other eye diseases, say scientists.
They have found that the healthful substances found in green tea renowned for their powerful antioxidant and disease-fighting properties - do penetrate into tissues of the eye.
The new study has documented how the lens, retina, and other eye tissues absorb these substances.
Chi Pui Pang and colleagues pointed out that so-called green tea "catechins" have been among a number of antioxidants thought capable of protecting the eye.
Those include vitamin C, vitamin E, lutein, and zeaxanthin. Until now, however, nobody knew if the catechins in green tea actually passed from the stomach and gastrointestinal tract into the tissues of the eye.
The researchers resolved that uncertainty in experiments with laboratory rats that drank green tea. Analysis of eye tissues showed beyond a doubt that eye structures absorbed significant amounts of individual catechins.
The retina, for example, absorbed the highest levels of gallocatechin, while the aqueous humor tended to absorb epigallocatechin. The effects of green tea catechins in reducing harmful oxidative stress in the eye lasted for up to 20 hours.
"Our results indicate that green tea consumption could benefit the eye against oxidative stress," the study concluded.
The study appears in ACS' bi-weekly Journal of Agricultural and Food Chemistry.