Aging-related decline in the liver and brain is accelerated by refined diet consumption

Studies suggest that diets rich in highly/ultra-processed foods may contribute to the development of diseases. In rodents, the intake of refined (purified) diets has also been associated with the development of various metabolic diseases. Here, performing two experiments, we assess the impact of a refined diet with and without fiber enrichment on aging related health decline in mice. Experiment 1: Male C57BL/6J mice were fed standard chow or refined diet until the age of 86 weeks. Experiment 2: Male C57BL/6J mice fed a refined diet until showing signs of aging related intestinal barrier dysfunction were fed a fiber enriched refined diet (7.5% oat β-glucan or 7.5% cellulose) for 18 weeks. Cognition was assessed at the beginning and end of the dietary fiber intervention, while glucose tolerance was determined at the end of each experiment. Markers of senescence, liver damage, neuroinflammation, intestinal barrier function, and microbiota composition were assessed. Refined diet-fed mice showed higher markers of senescence in plasma and aging-associated liver decline, impaired glucose metabolism and cognitive decline compared to standard diet-fed mice. These changes were associated with differences in intestinal microbiota composition and higher portal bacterial endotoxin levels. Enriching the refined diet with the fibers decelerated the aging-associated cognitive impairments while not affecting aging-related liver decline, insulin resistance or markers of intestinal barrier function. In conclusion, these data suggest that while decelerating aging-related cognitive decline, fiber fortification of a refined diet may not attenuate the diet-induced acceleration of aging related decline in other organs in mice.