The gut microbiota contains trillions of bacteria, viruses and fungi that profoundly influence health. As we age, so does the gut microbiota, and age-related changes in the gut microbiota can contribute to memory loss. The diet shapes the gut microbiota and, in return, the gut microbiota can regulate whether we have a health response to our diet. We previously found a 30% reduction in calories consumed prevented age- and AD-related changes in the gut microbiota of mice, and found that it suppressed a specific bacterium that contributed to amyloid beta plaque deposition. While this is a promising finding, calorie restriction may lead to malnutrition in the elderly, highlighting a need for other approaches. There is epidemiologic evidence that the Mediterranean diet—with high polyphenols, high fiber and high unsaturated fat—may help prevent AD, whereas the Western diet—characterized by low fiber, high sugar and high saturated fat—increases AD risk. This proposal will identify microbes altered by the Mediterranean and Western diets that are linked to amyloid load and memory in an animal model of AD. Furthermore, it will test whether administering a beneficial microbe can improve dietary response. We then will identify metabolic and immunologic changes. This may lead to novel ways to prevent and treat AD by harnessing the metabolic potential of the gut microbiota.
