Age Versus Immunity: Dietary Influences on Immunosenescence

Background: Immunosenescence, or the age-related weakening of the immune system, leads to greater susceptibility to chronic diseases, infections, and metabolic disorders. This process involves changes in the number and function of lymphocytes, increased levels of inflammatory markers, and modifications to the gut microbiome. In recent years, increasing importance has been placed on diet—both functional, rich in bioactive ingredients, and conventional, often pesticide-laden—as a factor modulating immune system aging. Methods: This paper provides a literature review on the effects of dietary components on immunosenescence. Results from 2010 to 2025 and from clinical and experimental studies on substances such as curcumin, butyrate, vitamin D3, omega-3 fatty acids, and conventional products containing pesticides were analyzed. Their impact on the microbiome, intestinal barrier integrity, inflammatory biomarkers, and the overall immune response was considered. Results: Numerous beneficial effects of functional foods were identified. Curcumin increases microbiota diversity and lowers C-Reactive Protein (CRP) and Tumor Necrosis Factor α (TNF-α) levels. Butyrate supports remission in inflammatory bowel disease by reducing Interleukin (IL) 6 and TNF-α levels. Vitamin D3 lowers inflammatory markers and reduces calprotectin in inflammatory bowel disease. Omega-3 fatty acids modulate microbiome composition and improve lipid profiles. In contrast, conventional foods high in pesticides lead to dysbiosis, intestinal barrier damage, and increased pro-inflammatory cytokines. Conclusions: Diet is a key factor in modulating immunosenescence. Functional foods can support the microbiome and reduce chronic inflammation, while conventional foods may exacerbate the aging process of the immune system. Further clinical research is needed to develop dietary recommendations to support immunity in older adults.