For the first time, researchers have created a form of the omega-3 fatty acid docosahexaenoic acid (DHA) capable of crossing into the retina of the eye and preventing visual decline associated with Alzheimer’s disease, diabetes, and other disorders.
DHA in fish oil capsules and other supplements is usually in the form of triacylglycerol (TAG) DHA. TAG-DHA has benefits in other parts of the body, but it cannot travel from the bloodstream into the retina, so it does not reach the eyes. The researchers developed a new lysophospholipid form of DHA, known as LPC-DHA, for the study. LPC-DHA successfully increased DHA in the retina and reduced eye problems associated with Alzheimer’s-like processes in mouse studies.
“Dietary LPC-DHA is enormously superior to TAG-DHA in enriching retinal DHA and could be potentially beneficial for various retinopathies in patients,” said Sugasini Dhavamani, a research assistant professor in the Department of Medicine at the University of Illinois at Chicago. “This approach provides a novel therapeutic strategy for the prevention or mitigation of retinal dysfunction associated with Alzheimer’s disease and diabetes.”
Dhavamani will present the findings at Discover BMB, the American Society for Biochemistry and Molecular Biology’s annual meeting, which will be held March 25-28 in Seattle.
Dietary LPC-DHA is enormously superior to TAG-DHA in enriching retinal DHA and could be potentially beneficial for various retinopathies in patients. This approach provides a novel therapeutic strategy for the prevention or mitigation of retinal dysfunction associated with Alzheimer’s disease and diabetes.
Sugasini Dhavamani
DHA is concentrated in the retina of healthy eyes, where it aids in the maintenance of photoreceptors, the cells that convert light into signals that are sent to the brain. DHA deficiency in the retina is linked to vision loss. People with Alzheimer’s disease, as well as those with diabetes, retinitis pigmentosa, age-related macular degeneration, and peroxisomal disorders, frequently have abnormally low levels of retinal DHA, and visual impairments are common as a result.
While increasing DHA content can help to prevent such declines, increasing retinal DHA content has been difficult with currently available supplements. In order for a dietary supplement to deliver DHA to the retina, the DHA must first be absorbed from the intestine into the bloodstream and then cross from the bloodstream into the retina.
“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 Dhavamani. “This study uses the novel approach of dietary LPC-DHA that overcomes both intestinal and blood-retinal barriers and improves retinal function.
The researchers tested their LPC-DHA supplement in mice bred to exhibit processes similar to those found in early-onset Alzheimer’s disease. After six months, mice that were fed LPC-DHA daily showed a 96% improvement in retinal DHA content as well as preserved retinal structure and function. In contrast, TAG-DHA supplements had no effect on retinal DHA levels or function.
The findings imply that LPC-DHA supplements may aid in the prevention of Alzheimer’s-related declines in visual function. According to the researchers, the approach should be useful for other disorders where DHA deficiency and vision impairment are common.
The LPC-DHA dosage used in the study is roughly equivalent to 250 to 500 milligrams of omega-3 fatty acids per day in humans. Because these studies were conducted on mice, more research would be required to confirm that LPC-DHA is safe and effective for human use.
