Flavor Enhancer MSG Linked to Blindness in Rats Wed Oct 23, 2:23 PM ET
LONDON (Reuters) - High levels of a flavor enhancer common in oriental and processed food can cause serious eye damage and blindness in rats and possibly humans.
Scientists at Hirosaki University in Japan said rats fed a diet high in monosodium glutamate, or MSG, suffered vision problems and had thinner retinas than other animals.
Glutamate has already been shown to cause nerve damage when it is directly injected into the eye but Hiroshi Ohguro, who led the research team, said their study is the first to show that eating foods containing high levels of MSG can cause eye damage.
"Lesser amounts should be OK," he told New Scientist magazine Wednesday, "but the precise borderline amount is still unknown."
Ohguro believes his findings, which were reported in the journal Experimental Eye Research, could explain why there is a high rate of a particular type of glaucoma in eastern Asia but it could also be due to genetics.
Glutamate is a neurotransmitter, or message-carrying chemical. Ohguro and his team found high levels of MSG in fluid that bathes the retina in the rats. They think it reduces sight by destroys some retina cells and damaging others.
The scientists fed rats three diets containing different levels of MSG. Rats which had the high and moderate levels of MSG had eye damage.
The amount of MSG given to rats is much higher than people would normally consume, according to Peng Tee Khaw, an eye expert at Moorfields Eye Hospital in London.
"But if you're a sodium glutamate junkie, then you could potentially run into problems with your retina," he said.