December 05, 2004.
Eating your greens can help prevent cataracts, laboratory evidence has confirmed for the first time.
Anti-oxidants in dark green leafy vegetables such as spinach and kale have been found to protect eye cells from exposure to ultraviolet light - a leading cause of cataracts.
Researchers in the US found that the antioxidants lutein and zeaxanthin were almost 10 times more powerful than vitamin E in protecting the cells from UV-induced damage.
Vitamin E is another antioxidant thought to reduce the onset of eye diseases.
Manufacturers of vitamins often add lutein and zeaxanthin to their products.
But until now there has been no biochemical evidence to support the claim that they help protect the eyes, according to researcher Joshua Bomser, from Ohio State University.
"Along with the many environmental, lifestyle and genetic risk factors associated with cataracts, exposure to ultraviolet radiation from sunlight and oxidative stress appear to be the most relevant in this disease," Prof Bomser said.
"Our results are the first to provide physical evidence suggesting that lutein and zeaxanthin decrease damage caused by ultraviolet radiation."
Cataracts cause the lens of the eye to cloud over and can lead to serious problems with vision.
It is estimated that around 71% of over-85s have a cataract bad enough to affect their sight, with women more commonly affected than men.
In the latest study, published in the Journal of Nutrition, the researchers treated human eye lens cells with different concentrations of lutein, zeaxanthin or vitamin E.
Along with a batch of untreated cells, these were exposed to doses of ultraviolet beta radiation for 10 seconds.
UVB radiation is also thought to be the main environmental culprit in causing skin cancer as well as cataracts.
Prof Bomser said the dose of UVB radiation they used was about the same amount a person would receive when they get a mild tan.
Adding lutein and zeaxanthin to the cell cultures provided double the protection from UVB damage compared with vitamin E.
The researchers also found that it took far less lutein and zeaxanthin than vitamin E - about 10 times less - to get this protective effect.
Prof Bomser said: "The lens is equipped with antioxidant defence mechanisms designed to guard against the harmful effects of ultraviolet radiation and oxidative stress.
"In addition to protective enzymes and compounds like vitamins C and E, we think that low concentrations of lutein and zeaxanthin in the eye lens help shield the eye from the harmful effects of UVB radiation."
The researchers said they did not know how the two antioxidants got into the eye and wanted to find out.
"Lutein and zeaxanthin accumulate in the retina and in the lens of the eye, but we're not sure how they reach the eye in the first place.
"They travel through the bloodstream but the lens doesn't have a blood supply," Prof Bomser said.
Anita Lightstone, the RNIB's head of eye health, said: "The Royal National Institute of the Blind welcome this latest research because we have recommended for some time that eating more leafy green vegetables is important for maintaining good eye health.
"Research also shows that eating a diet rich in antioxidant vitamins can help prevent age-related macular degeneration, the biggest cause of blindness in the UK."
Source URL: http://news.scotsman.com/latest.cfm?id=3844805.
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