Summary:
This review examines the role of the immune system in maintaining health across the lifespan, highlighting that immunity extends beyond infection protection and includes regulation of inflammation, tissue repair and physiological balance. Immune resilience is influenced by genetic, environmental and lifestyle factors, including nutrition, physical activity, stress, sleep, microbiome composition and previous exposures. Immune function changes throughout life, from early development and maturation to age-related decline. Early-life factors such as maternal antibodies, breastfeeding, nutrition and microbiome development help establish effective immune responses, while hormonal changes, environmental exposures and lifestyle behaviours shape immunity throughout childhood and adolescence. In adulthood, factors including chronic stress, poor sleep, inactivity, pollution and metabolic disturbances can gradually reduce immune resilience, while pregnancy and menopause involve further immune adaptations. A key focus of this review is the role of micronutrients in supporting immune function. Vitamins A, C, D, E, B6, B9 and B12, and minerals such as zinc, selenium, iron and copper, contribute to immune cell development, antibody production, inflammatory regulation and protection against oxidative damage. Inadequate intake of these nutrients may impair immune responses and increase susceptibility to infection and chronic inflammation. Although dietary recommendations are designed to prevent nutrient deficiencies, evidence suggests that higher nutrient intake may be required during periods of increased demand such as infection, pregnancy, ageing and chronic disease. Suboptimal micronutrient status remains common and may reduce immune effectiveness, while improving nutrient intake through diet or supplementation has been associated with enhanced immune markers and improved responses to infections. Overall, this review highlights that immune resilience is shaped by lifelong interactions between nutrition, lifestyle, environmental factors and ageing. Maintaining adequate micronutrient intake may help support immune function, improve protection against infection and promote healthier ageing.
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Abstract:
The immune system constitutes a physiological network that preserves organismal stability through continuous interactions with tissues and regulatory systems. Immune activity is an integral component of normal tissue physiology, contributing to host defense, structural integrity, metabolic balance, and functional homeostasis. The immune system integrates molecular recognition, effector mechanisms, and inflammation resolution to control infections, limit tissue damage, and reduce the progression of chronic and degenerative diseases. These combined defensive and physiological functions underpin the concept of the immune system as a “guardian of health.” Immune competence varies across the life course, following a dynamic trajectory shaped by development, maturation, stabilization, and age-related decline (immunosenescence). Early life, adolescence, pregnancy, menopause, and aging are characterized by increased immune plasticity and shifting functional demands. In later life, immunosenescence and chronic low-grade inflammation (inflammaging) increase immune vulnerability, to the extent that immune resilience determines interindividual variability with aging and subsequent health outcomes. Micronutrients are central determinants of immune resilience, as they support immune cell proliferation and function, redox balance, epithelial barrier integrity, and inflammation control. Vitamins A, C, D, E, and the B-group, together with trace elements such as zinc, selenium, iron, and copper, act within interconnected metabolic and signaling networks that sustain innate and adaptive immune responses. Despite their essential role, subclinical micronutrient insufficiencies remain common, including in high-income countries, and are associated with reduced immunocompetence and increased susceptibility to infection and inflammation. Overall, this evidence highlights that life-course-based immunonutrition could be a strong strategy to preserve health-span and promote long-term physiological resilience.
Article Publication Date: 09/04/2026
DOI: 10.3389/fnut.2026.1802025
