What these products are
Immunity blends, elderberry syrups, mushroom complexes and megadose vitamins sold against colds and "low immunity." The educational base: the Immune hub, the vitamin C, vitamin D and zinc evidence files, and the full boosters verdict.
What they cannot do
- "Boost" a healthy immune system — overactivation is allergy and autoimmunity; no trial shows useful above-baseline enhancement.
- Beat the boring quartet — vaccination, sleep, exercise and glucose control outperform the shelf in every comparison that exists.
- Transfer the deficiency story to the replete — the C, D and zinc pages document the nulls and the megadose costs (stones, hypercalcemia, copper loss).
The evidence, in one table
| Product type | Evidence | Honest role |
|---|---|---|
| Correcting D or zinc deficiency | Moderate–strong | The kernel — test-directed, correction-dosed |
| Zinc lozenges, strict protocol | Limited | ~1–2 days off colds; drugstore formats mostly miss the recipe |
| Daily vitamin C through winter | Limited | ~8% shorter colds; heavy-exerciser prevention niche |
| Elderberry | Limited | Small trials; cooked products only |
| Echinacea, mushroom blends | Mixed/insufficient | Big trials null; lab data selling capsules |
| Multi-ingredient "immunity" blends | Insufficient | Sub-protocol doses of the rows above |
What our reviews check
Lozenge formats and elemental zinc against the protocol, dose honesty versus decoration, copper pairing at high zinc, "boost" claim language, and seller terms as verified. Reviewed products appear below; review pages carry disclosed affiliate links — this page carries none.