MSG linked to eye problems: study

Monosodium glutamate (MSG), a flavouring found commonly in Chinese food, has been linked to loss of some vision in laboratory mice.

Researchers at Hirosaki University in Japan fed rats diets high in MSG and discovered they suffered vision loss and had thinner retinas.

The results are published in New Scientist magazine and the journal Experimental Eye Research.

Researchers say MSG binds to the receptors in cells on the retina and destroys them. The retina is an area at the back of the eye that receives images and carries the sight signals to the brain.

This reduces the ability of the cells which are left to relay electrical signals.

The Japanese team fed rats three different diets for six months: with high or moderate amounts of MSG or none.

Rats given the highest amount of MSG 20 per cent of their diet showed some eye damage. Some retinal nerve layers thinned by as much as 75 per cent. They were also unable to see natural light as well.

Lead researcher Hiroshi Ohguro says the study shows why there is a high level of normal tension glaucoma in eastern Asia.

Normal tension glaucoma is also known as low tension glaucoma or normal pressure glaucoma. In this type of glaucoma, the optic nerve is damaged even though pressure within the eye is normal. Doctors can't figure out why the optic nerve is damaged.

Normal-tension glaucoma can lead to blindness.

Researchers and other scientists stress the rats were given a huge amount of MSG.

Peng Tee Khaw, a British eye expert, says those who eat too much take-out food or may have pre-existing retinal problems should consider cutting down on their intake.