Zinc Bisglycinate Chelate
Zinc Bisglycinate Chelate is a unrated form of Zinc, used in 833 on-market products and providing 30.6% elemental zinc by weight.
Basis: Zn(C2H4NO2)2, anhydrous bisglycinate
Why this tier: Zinc bisglycinate was absorbed better than zinc sulphate in a rat model with dietary phytate (overall bioavailability ~49% vs ~42%; Schlegel & Windisch 2006). In a small human crossover (n=12 women, single 15 mg dose) bis-glycinate raised serum Zn AUC 43% above gluconate (Gandia et al. 2007); a single small pharmacokinetic study, so no consistent superiority is established and no tier is assigned.
Source: Schlegel P, Windisch W. 2006, J Anim Physiol Anim Nutr 90(5-6):216-22, PMID 16684142 (rats); Gandia P et al. 2007, Int J Vitam Nutr Res 77(4):243-8, PMID 18271278 (human crossover, n=12)