The immune system is a complex network that depends on dozens of micronutrients to function. There is no single "superfood" that boosts immunity, but a consistently nutrient-dense diet dramatically reduces the frequency and severity of infections.

Key Immune-Supporting Nutrients

  • Vitamin C: Found in citrus fruits, kiwi, bell peppers, and broccoli. Supports the production and function of white blood cells. 500–1,000 mg daily during illness can shorten cold duration.
  • Vitamin D: The most important immune-regulating vitamin. Deficiency is epidemic — especially in winter at northern latitudes. 2,000–4,000 IU/day is recommended for most adults, ideally guided by blood testing.
  • Zinc: Found in meat, shellfish, legumes, and seeds. Critical for T-cell development. Even mild deficiency impairs immune response.
  • Probiotics: 70% of the immune system lives in the gut. Fermented foods (yoghurt, kefir, sauerkraut) and probiotic supplements support the gut microbiome, which directly trains immune tolerance.
  • Beta-glucans: Found in oats and medicinal mushrooms (reishi, shiitake). Clinically shown to enhance natural killer cell activity.

Lifestyle Factors That Matter as Much as Diet

Sleep deprivation cuts natural killer cell activity in half after just one night. Regular moderate exercise increases immune surveillance. Chronic alcohol consumption and smoking both profoundly suppress immune function. No supplement compensates for these fundamentals.