The Black Vault - Take-away diet could damage your eyesight

Too many Chinese take-aways could damage your eyesight, according to new research.

Scientists found eating large amounts of monosodium glutamate, used to flavour oriental and processed foods, can injure the retina and lead to vision loss.

Rats fed diets high in monosodium glutamate (MSG) in Japan developed thinner retinas and began to go blind.

Glutamate is an amino acid which acts as a neurotransmitter, a chemical that sends signals between nerve cells. Previous research has already shown that it causes nerve damage when injected directly into the eye.

But the Japanese study at Hirosaki University was the first to show that eye damage can be caused by eating food containing MSG.

Rats were fed three different diets for six months, containing either high or moderate amounts of MSG, or none. In animals on the high MSG diet, some retinal nerve layers thinned by as much as 75%. Tests to measure retinal response to light showed that the rats' vision was impaired.

Those on the moderate diet also suffered damage, but to a lesser extent.

He said the findings might explain why in eastern Asia there was a high rate of normal tension glaucoma. This is a form of the eye disease that leads to blindness without the usual increase in pressure inside the eyeball. However, the higher incidents rate could also be due to genetic factors.

Professor Peng-Tee Khaw, a glaucoma expert at Moorfields Eye Hospital in London, said the amount of MSG in the highest diet was "a lot, lot higher than you'd eat". But he added: "If you're a sodium glutamate junkie then you could potentially run into problems with your retina."

While the amount of glutamate fed to the rats was extremely high, lower dietary intakes could produce the same effects over several decades, said Professor Khaw. This may be why people tended not to develop normal-tension glaucoma until they were in their forties.

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