Abstract
Aging is associated with immune senescence and gut dysbiosis, both of which are heavily influenced by the diet. In this review, we summarize current knowledge regarding the impact of diets high in fiber, protein, or fat, as well as different dietary components (tryptophan, omega-3 fatty acids, and galacto-oligosaccharides) on the immune system and the gut microbiome in aging. Additionally, this review discusses how aging alters tryptophan metabolism, contributing to changes in immune function and the gut microbiome. Understanding the relationship between diet, the gut microbiome, and immune function in the context of aging is critical to formulate sound dietary recommendations for older individuals, and these personalized nutritional practices will ultimately improve the health and longevity of the elderly.