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One hot cup of tea per day may help to prevent glaucoma
There have been many claims made to the benefits of tea consumption, including better oral health, lower incidences of dementia and Alzheimer's disease, decreased risk of ovarian cancer and seemingly a mechanism that breaks down your fat (I'll be using that one over this festive period when I've done nothing but eat and sit still).

But a study published in the British Journal of Ophthalmology on Dec 14th shows another possible benefit to your morning cuppa: people who drink hot tea are less likely to suffer from glaucoma.

That's the finding of professor of ophthalmology, Anne Coleman, and colleagues at David Geffen School of Medicine at the University of California, Los Angeles.

Glaucoma is a condition whereby fluid pressure builds up inside the eye. The damage this causes to the optic nerve makes glaucoma one of the leading causes of blindness worldwide, affecting almost 60 million people a year.

Coleman et al used data from an annual survey known as NHANES (National Health and Nutrition Examination Survey), which consists of selecting around 10,000 U.S. adults and children and asking them about their lifestyles, taking blood samples and giving them a physical examination. The NHANES survey conducted in 2005/06 happened to include screening for glaucoma also, making it perfect for the team analyse.

Even after controlling for other possible contributing factors such as smoking and diabetes, those who drank at least one cup of hot tea per day had a 74% decreased risk of developing the condition than those who drank none at all.

1678 of the people who took part in the survey had full eye-screenings, of which, 84 (5%) had glaucoma. The results did not indicate when they had received their diagnosis, and did not go into detail about which type of tea people drank or how long they brewed it for.

The data included not only hot tea, but iced tea, coffee, decaff tea and coffee, and sodas. The benefits were only found in those participants who drank hot tea, and not in those who preferred the other beverages. Caffeine has been previously linked to alteration in ocular pressure, and so coffee might have been expected to aid the condition. However, compared to tea, coffee has fewer flavanoids which have been shown to have antioxidant and anti-inflammatory properties and which may be acting to prevent the condition. As for decaffeinated tea, it too has fewer antioxidants than regular tea.

No benefit was found from drinking sodas or iced tea, but for iced tea there is the problem of sample-size: it's just not as popular a drink as the others.

The analysis only shows a correlation, not a causation, and Coleman et al admit that more research would need to be done to investigate the affect in more detail.

You can read the paper by clicking on this link.