Deficiency correction, not immune 'boosting'

Immune Health & Aging

Immune function changes with age (immunosenescence). Correcting a genuine nutrient shortfall helps; layering on 'immune boosters' does not have comparable support.

What the evidence says

  • Zinc and vitamin D deficiency are more common after 65 and are worth testing for rather than guessing at.
  • Vaccination remains the best-evidenced immune intervention for older adults.
  • Long-term high-dose zinc can cause copper deficiency — a real risk in this age group.

Supplements in this topic

Vitamins

Vitamin D

Moderate evidence

Essential for bone health and immune function. Supplementation helps people who are deficient, but routine mega-dosing shows mixed benefits for healthy adults.

Verdict: Worth taking if deficient; test levels first.

850 studies reviewed
Fat-soluble toxicity risk at very high doses
Minerals

Zinc

Strong evidence

Effective at reducing the duration of common cold symptoms when started early and supports immune function in deficient individuals.

Verdict: Works for acute colds and deficiency.

290 studies reviewed
Nasal zinc can cause permanent smell loss
Probiotics

Probiotics

Mixed evidence

Helpful for specific conditions like antibiotic-associated diarrhea and some IBS subtypes. General health benefits are highly strain-specific.

Verdict: Strain-specific effects; not a one-size-fits-all health booster.

380 studies reviewed
Benefits depend on specific strain and dose

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