Zinc Sulfate
Zinc Sulfate is a tier 2 form of Zinc, used in 434 on-market products and providing 22.7% elemental zinc by weight.
434
on-market products
tier 2
quality tier
22.7%
elemental fraction
Basis: ZnSO4 x 7H2O, heptahydrate (classic OTC form; a monohydrate at 0.364 also exists commercially -- check specific labels)
Why this tier: WHO/UNICEF-recommended form for diarrhea-management zinc dosing and the classic reference standard in absorption literature. In one small preliminary isotope study (n=8, 2 mg 70Zn given with milk, crossover) fractional absorption of gluconate was significantly higher than that of sulfate; no larger head-to-head human isotope comparison was verified.
Source: Piacenza F et al. 2023, Nutrients 15(8):1885, PMID 37111104 (preliminary, n=8); WHO/UNICEF clinical-use basis