Low glycemic diet may halt progression to age-related macular degeneration

Changing a high glycemic (HG) diet to a low glycemic (LG) one, even late in life, may halt the development of age-related macular degeneration (AMD), according to research results published in the Proceedings of the National Academy of Sciences. Furthermore, they found that diet may have a significant impact on metabolic changes, the gut microbiome, and the development of AMD.

AMD currently affects over 2 million Americans, and is the leading cause of vision loss in those aged 50 years and older. For dry AMD, no effective treatments are available.

Researchers conducted this study in wild-type mice, and used metabolomics to determine associations between metabolism, diet, and AMD phenotypes. Forty mice were fed the HG diet, and 19 the LG diet. Six months after study initiation, 17 mice were changed from the HG to the LG diet, and another 6 months later, the three groups of mice were analyzed for any differences.

The HG mice developed numerous AMD features (AMDf), including retinal pigment epithelial (RPE) hypopigmentation and atrophy, lipofuscin accumulation, and degephotoreceptor degeneration. Conversely, LG mice did not have AMDf, and exhibited limited accumulation of advanced glycation end poducts, long-chain polyunsaturated lipids and their peroxidation end-products, and increased C3-carnitine in the retina, plasma, or urine.

In the mice who had been switched to the LG diet, gut microbiome levels had been restored, researchers noted. In addition, they observed an association between microbiota in the Clostridiales order with AMDf and the HG diet. Microbiota in the Bacteroidales order were associated with protection from AMDf and the LG diet. Upon network analysis, researchers observed that metabolites and microbiota seem to work in the gut-retina axis to protect against diet- and age-induced AMDf.

“Our findings show an interaction between dietary carbohydrates, the gut microbiome, specific biochemical molecules, and AMD features. This work should lead to new approaches to understand, diagnose, and treat early AMD—perhaps before it affects vision,” said senior author Allen Taylor, PhD, professor of nutrition, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA. “Already anticipated by our human epidemiologic studies, the findings imply that we can optimize nutrition to prevent the progression of AMD.”