Previous studies suggest that diets with low glycemic index can delay the progression of atrophic age-related macular degeneration (AMD), a retinal disease that is marked by loss of retinal pigment epithelium (RPE) and photoreceptors and is known to be a leading cause of blindness.
Researchers. report that 12-month-old wild-type mice fed a high-glycemic (HG) diet for 1 year exhibited greater photoreceptor loss than mice fed a low-glycemic (LG) diet of similar caloric content; switching mice to an LG diet after 6 months appeared to arrest and reverse photoreceptor damage.
In contrast to the RPE of mice fed an LG diet, the RPE of HG mice showed reduced pigmentation, increased atrophy, and accumulation of lipofuscin pigments—all of which are hallmarks of AMD. Similarly, HG mice showed increased blood levels of advanced glycation end products, which are markers of cytotoxic stress.
Metabolic analysis uncovered an array of urinary and plasma metabolites, including the neurotransmitter serotonin, as potential biomarkers for AMD. Notably, microbiome analysis revealed a protective effect for LG diets that was tied to enrichment of the Bacteroidales order of gut microbes as well as a predisposing effect for HG diets that was tied to enrichment of the Clostridiales order.
According to the authors, the findings suggest a potential protective role for LG diets in atrophic AMD.