Growing evidence suggests that environmental factors associated with AMD progression may be related to intestinal health. The composition of bacterial flora in this system—the gut’s microbiome—plays an important role in some diseases with inflammatory components, such as AMD.

Researchers noted in a recent review paper published in the Journal of Clinical Medicine that diets high in fat exacerbated both wet and dry AMD features in a cohort of mice, “presumably through changes in the intestinal microbiome” and other independent mechanisms like lipid metabolism. Notably, other studies showed that AREDS vitamin supplements demonstrated reversal of adverse intestinal microbial changes in AMD patients.

“Part of the mechanism of intestinal microbial effects on retinal disease progression is via microbiota-induced microglial activation,” the researchers wrote in their study. “The microbiota are at the intersection of genetics and AMD. Higher genetic risk was associated with lower intestinal bacterial diversity in AMD. Microbiota-induced metabolite production and gene expression occur in pathways important in AMD pathogenesis.”

The researchers concluded that the studies they reviewed suggest “a crucial link between intestinal microbiota and AMD pathogenesis, thus providing a novel potential therapeutic target.” They recommended large-scale longitudinal studies in both patients and germ-free or gnotobiotic animal models to investigate.