Copper Citrate
Copper Citrate is a tier 2 form of Copper, used in 423 on-market products and providing 35.3% elemental copper by weight.
423
on-market products
tier 2
quality tier
35.3%
elemental fraction
Basis: Real ambiguity between two documented compounds: Cu3(C6H5O7)2 anhydrous (0.335) vs. Cu2(C6H4O7) x 2.5H2O hemipentahydrate, CAS 10402-15-0 (0.353, used here as the CAS-documented commercial solid)
Why this tier: Marketed as a bioavailable organic copper salt; no direct human comparative bioavailability RCT located.
Source: uncertain -- needs review