Best supplements for immunity.

The supplements with real evidence for supporting immune function, and which to reach for at the first sign of a cold.

Written to our editorial standards · reviewed against published research· Updated 2 Jun 2026
Each pick is evidence-graded · we don't sell supplements
  1. 1Vitamin D3 + K2StrongSupports mood, immune function, bone health, and calcium routing. Especially valuable indoors or above 40° latitude.5000 IU D3 + 90 mcg K2 · morning · ~$12/mo
  2. 2Zinc PicolinateStrongCritical for immune function, testosterone synthesis, taste, and skin health. Most modern diets fall short.15 mg · evening · ~$9/mo
  3. 3Saccharomyces boulardiiVery strongA beneficial yeast probiotic. The best-evidenced supplement for preventing antibiotic-associated diarrhea.5 billion CFU · morning · ~$22/mo
  4. 4Vitamin CStrongImmune support, antioxidant defense, and collagen synthesis. Buffered form is gentler on the stomach.1000 mg · morning · ~$9/mo
  5. 5N-Acetyl CysteineStrongPrecursor to glutathione, the body's master antioxidant. Supports liver detox, lung function, and recovery from oxidative stress.600 mg · morning · ~$14/mo
  6. 6Multi-Strain ProbioticModerateSupports digestive balance, immune signalling, and the gut-brain axis that influences mood and cognition.50B CFU, 15 strains · morning · ~$35/mo
  7. 7SeleniumStrongCritical for thyroid hormone conversion and glutathione peroxidase, one of the body's main antioxidant enzymes.200 mcg · morning · ~$10/mo
  8. 8Cranberry ExtractStrongConcentrated extract delivering 36 mg PACs daily, the dose shown to reduce recurrent UTI risk. Replaces drinking gallons of juice.500 mg standardised · morning · ~$18/mo
  9. 9Aged Garlic ExtractStrongAged at low heat for 20+ months, odorless, with concentrated, stable bioactives clinically shown to support healthy cholesterol and BP.1200 mg · morning · ~$22/mo
  10. 10Zinc-CarnosineStrongA chelated form of zinc and L-carnosine that adheres to the stomach lining. Heals erosions and supports H. pylori protocols.75 mg · morning · ~$26/mo
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Common questions

What are the best supplements for immunity?
Vitamin D is foundational (especially if you're low); zinc and vitamin C (with quercetin) are most useful at the onset of a cold; elderberry may shorten symptoms.
Does vitamin C prevent colds?
Vitamin C doesn't reliably prevent colds in most people, but it may modestly shorten them, especially when started early and paired with zinc.

Educational use only, not medical advice. Always consult a qualified clinician before starting supplements, especially if you take medication or are pregnant or nursing.