The Microbiome's Impact on Age-Related Macular Degeneration

Recent studies suggest that the types of bacteria that live in our intestines can influence susceptibility to certain diseases, including age-related macular degeneration (AMD).

Helpful Foods

There is strong evidence that a diet with daily fruits and vegetables and twice-a-week fatty fish such as salmon can protect against AMD. In contrast, diets high in red meat, sugar/simple carbohydrates, and the types of fat found in processed snack foods increase the risk of AMD.

Diet and Inflammation

The protective foods tend to be anti-inflammatory, while the high-risk foods can increase inflammation. This is important for AMD patients because AMD is associated with inflammation. Blood levels of several markers of inflammation, such as C-reactive protein (CRP) and interleukin 6 (IL-6) are higher in AMD patients compared to controls in a study published by Dr. Johanna Seddon at Harvard. Also, pro-inflammatory activation of a part of the immune system called the “complement cascade” is linked to AMD.

Research Findings

Protective foods may be anti-inflammatory because they change the composition of the microbiome. Several recent studies support this idea:

• A study by Dr. Allen Taylor at Tufts shows that mice given a high-sugar diet have an altered microbiome and develop features of AMD.


• In addition, Dr. Mike Sapieha at the University of Montreal and McGill University reported similar findings with a high-fat diet.


• Research in humans by Dr. Martin Hibberd at the Genome Institute of Singapore and Dr. Wolf at Bern University Hospital showed differences in the gut microbiome in AMD patients compared to controls.


• Another recent study published in Nature by Dr. Huihui Chen at Harvard shows that mice with glaucoma and raised without a microbiome are protected from glaucoma relative to mice with a microbiome. This effect is mediated by immune cells called T cells.  While glaucoma is a different eye disease from AMD, both involve immune cells in the eye and, ultimately, death of neurons in the retina.

Summary

Together, these findings emphasize the importance of an anti-AMD diet, not just to reduce the risk of vision loss, but to diminish systemic inflammation that can promote heart disease, arthritis, Alzheimer’s disease, and probably glaucoma too.

Another potential way to get a healthier microbiome is to take probiotic pills. These pills contain a few species of bacteria that are thought to promote health, such as the lactobacillus found in yogurt. These bacteria compete for space and nutrients in the gut with other, potentially pro-inflammatory bacteria. Several studies show that probiotics can decrease systemic inflammation. While this approach has not yet been tested for AMD, it is worth asking your doctor if she/he recommends taking them in an effort to protect vision from AMD and, potentially, improve systemic health.