Question 1

Why does the cold lozenge protocol close after 24 hours?

Accepted Answer

Hemilä's 2017 individual-patient-data meta-analysis (PMID 28480298) found the recovery-rate benefit of zinc acetate lozenges is concentrated in the first 24 hours of symptom onset; later starts showed no consistent benefit. Cochrane 2024 (PMID 38719213) likewise rates later-start lozenges as low-certainty. The calculator returns a window-closed flag for any onset >24 h — save the lozenges for the next cold rather than dose into a closed window.

Question 2

When does the copper-offset gate fire?

Accepted Answer

Long-term zinc ≥25 mg/day induces copper deficiency by upregulating intestinal metallothionein, which sequesters dietary copper. The calculator adds a 1–2 mg copper (gluconate or bisglycinate) recommendation when your daily zinc is ≥25 mg/d, duration is long (≥3 months), and you are not already supplementing copper. Caught early it is reversible; chronic deficiency causes microcytic anemia, neutropenia, and myeloneuropathy.

Question 3

Why are vegan and PPI users dosed higher?

Accepted Answer

Phytate from grains and legumes binds zinc in the gut and cuts absorption 40–50% on plant-heavy diets (IZiNCG bioavailability adjustment). Chronic proton-pump inhibitor use produces achlorhydria, which compromises ionic-zinc absorption 30–50%. Both cohorts get a 1.5× dose multiplier and picolinate (chelated form, bypasses the gastric-acid step).

Question 4

Sulfate, gluconate, picolinate, or bisglycinate?

Accepted Answer

Bisglycinate is the gen-pop default — 60–70% bioavailable, excellent GI tolerance. Picolinate (60–65% bioavailable) is preferred for vegans / PPI users / athletes where the higher chelation matters. Citrate is a value alternative ($$ vs $$$). Acetate or gluconate lozenges are the only forms with cold-recovery evidence — never use intranasal zinc, which has caused permanent anosmia (FDA warning 2009).

Question 5

What about Wilson disease and AMD?

Accepted Answer

Both are out of scope. Wilson disease uses 150 mg elemental zinc/day (50 mg TID) for chelation-style copper management — physician-supervised per AASLD 2023 guidance (PMID 37184530). Age-related macular degeneration uses the AREDS2 80 mg/d formulation and is ophthalmology-supervised (PMID 35653117). Both are explicitly outside this calculator; bring them to your physician.

Question 6

How long is too long at supplemental doses?

Accepted Answer

The adult upper limit is 40 mg/d sustained. The calculator flags any long-duration dose above that threshold, and adds an HDL-suppression / inverted-U immunity warning at ≥150 mg/d. Acne courses run ~12 weeks; cold-lozenge courses 5–7 days; RDA gap-filling is ongoing at the lower 15–25 mg/d range. Reassess deficiency-context dosing at 8–12 weeks with serum zinc + RBC zinc if symptoms persist.