Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans

Barrie SA, Wright JV, Pizzorno JE, Kutter E, Barron PC · Agents and Actions

Hair, urine and erythrocyte zinc rose significantly during the picolinate period but not during gluconate, citrate or placebo — the study behind the claim that picolinate is the better-absorbed form.

Population

Healthy volunteers in a double-blind four-period crossover

Intervention

Zinc picolinate, zinc citrate or zinc gluconate (50 mg elemental zinc/day, 4 weeks each)

Comparator

Placebo and the other zinc salts

Limitations

n=15, indirect status markers rather than tracer kinetics, never replicated in 38 years; authors were affiliated with naturopathic practice (Bastyr founders); full text paywalled — appraised from the published summary.