Micronutrients and Immune Resilience: What Science Supports

Immune function depends on a steady supply of micronutrients for cell proliferation, antibody production, and inflammatory regulation. Deficiency impairs response; repletion restores it. However, the popular assumption that megadosing supplements "boosts" immunity in already-replete individuals lacks robust evidence.

Nutrients with the strongest immunological roles

Zinc is required for thymic function and T-cell maturation. Deficiency increases infection susceptibility and prolongs recovery. Supplementation shortens common cold duration modestly when started within 24 hours of symptom onset — but chronic high doses interfere with copper absorption.

Vitamin C supports epithelial barrier integrity and phagocyte function. Severe deficiency causes scurvy with impaired wound healing. Routine mega-supplementation in healthy adults shows minimal preventive benefit in large meta-analyses.

Vitamin D receptors exist on virtually all immune cells. Low levels associate with increased respiratory infection rates. Correcting deficiency reduces event frequency; supraphysiological dosing does not add proportional benefit.

Selenium at adequate levels supports antioxidant enzymes in immune cells. Both deficiency and excess impair function — a reminder that more is not always better.

Vitamin A maintains mucosal surfaces in respiratory and gastrointestinal tracts — the body's first physical defense layer.

Food-first approach by season

• Winter: citrus, fermented foods, fatty fish, mushrooms exposed to UV light
• Spring: leafy greens, asparagus, eggs, sprouted legumes
• Summer: berries, tomatoes, bell peppers, seeds
• Autumn: squash, root vegetables, nuts, poultry