The controversial taste-enhancer Monosodium glutamate (MSG) is once again in the centre of a debate. A recent research has found it to damage people's eyesight.

Scientists found that eating large amounts of MSG, used to flavour oriental and processed foods, can injure the retina and lead to vision loss.
 
Rats fed diets high in 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, says a report in Sydney Morning Herald.
 
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 per cent.
 
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.
 
Research, also showed high concentrations of MSG in the vitreous fluid which bathes the retina. MSG bound to molecules on retinal cells and destroyed them, causing secondary reactions that reduced the ability of the remaining cells to relay electrical signals, the report added.