A form of the fatty acid omega-3 could help to stave off the deterioration in vision caused by Alzheimer’s disease, diabetes and several other disorders, researchers at the University of Illinois at Chicago have found.
In a series of studies carried out on mice, the team found that a form of the omega-3 fatty acid docosahexaenoic acid (DHA) known as lysophospholipid DHA, or LPC-DHA, can be absorbed by the retina where it can help to combat loss of sight.
The research was presented at Discover BMB, the annual meeting of the American Society for Biochemistry and Molecular Biology, in Seattle.
In healthy eyes, DHA found in the retina helps to maintain photoreceptors – specialised neurons that convert light into electrical signals and send them to the brain via the optic nerve.
Patients with Alzheimer’s disease, diabetes, age-related macular degeneration and several other disorders have low levels of DHA, which often results in a loss of vision.
The form of DHA commonly found in fish oil supplements is the closely related triacylglycerol dHA, or TAG-DHA. However, this form cannot pass from the bloodstream to the retina.
The team found that mice bred to show similar symptoms to those found in early-onset Alzheimer’s disease showed a 96 per cent increase in retinal DHA after six months of being fed a daily LPC-DHA supplement. TAG-DHA supplements given over the same time period had no effect on retinal DHA levels.
The dosage used in the study was equivalent to about 500 milligrams in humans – an amount commonly found in fish oil capsules. However, further studies are needed to confirm that LPC-DHA is safe and effective for use in humans, the researchers say.
“Increasing the retinal DHA at clinically feasible doses has not been possible until now because of the specificity of the blood–retinal barrier that is incompatible with the specificity of the intestinal barrier,” said Dr Sugasini Dhavamani, a research assistant professor in the Department of Medicine at the University of Illinois at Chicago.
“This study uses the novel approach of dietary LPC-DHA that overcomes both intestinal and blood–retinal barriers and improves retinal function.”
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