Full profile
| Also known as | Zinc bisglycinate, Zinc citrate, Zinc picolinate |
|---|---|
| Best for | Correcting or insuring against zinc deficiency · Immune support · Adjunct (not standalone) mood support in deficiency |
| Evidence grade | Grade C — Limited — early or small human trials |
| Studied dose range | Everyday supplements ~8–15 mg elemental zinc/day; antidepressant-adjunct trials used ~25 mg/day. The tolerable upper limit is 40 mg/day elemental (set by copper-absorption interference). Declare elemental zinc — salts differ in elemental content. |
| Time to effect | Deficiency-related symptoms improve over weeks; antidepressant-adjunct trials measured effects at roughly 6–12 weeks. |
| Best form | Well-absorbed organic forms (bisglycinate, citrate, gluconate) over zinc oxide. Note zinc picolinate is more restricted under Health Canada (adults only, max 25 mg/day) — a non-picolinate chelate keeps dosing and claims more flexible. |
| Food sources | Oysters and shellfish, Red meat and poultry, Pumpkin seeds, Legumes, Fortified cereals |
Evidence, honestly graded
Claim-specific. Deficiency correction is well established, but the consumer-relevant claim — mood or cognition in generally-nourished adults — is limited. A meta-analysis found serum zinc is lower in depressed than non-depressed people (Swardfager 2013), which supports a deficiency-correction rationale but is an association, not a supplementation result. Supplementation trials show a modest antidepressant effect mainly as an add-on to medication and in people who are low (Lai 2012; Donig 2022, called "preliminary"). Graded C: a foundational nutrient whose felt effect in replete adults is weak.
See the full grading rubric — study type, replication, population match, and dose adequacy — in The Evidence Standard.
Side effects
- Nausea or GI upset, worse on an empty stomach
- Chronic high dose (~≥50 mg/day over weeks): copper deficiency, impaired immunity, lowered HDL cholesterol
Who should avoid it or check first
- Long-term high-dose use without balancing copper
- Known copper deficiency
Interactions
- Reduces absorption of quinolone and tetracycline antibiotics and of penicillamine — separate doses
- High zinc antagonizes copper; thiazide diuretics increase zinc loss
Stacks well with
- Copper (to offset depletion at higher zinc doses)
Use caution stacking with
- High-dose zinc without co-supplemented copper over the long term
What to look for on a label
- Declare elemental zinc (Health Canada dosing-error flag). Above 40 mg/day requires a specific use/purpose statement.
- Honest regulatory note: Health Canada's monograph does NOT permit cognition, mood, or depression claims for zinc — only structural/functional ones (immune function, tissue formation, etc.). At 31–50 mg/day, co-supplemented copper is required to avoid a copper-depletion caution.
References
- Lai J, Moxey A, Nowak G, Vashum K, Bailey K, McEvoy M (2012). Journal of Affective Disorders, 136(1-2):e31–e39Zinc reduced depressive symptoms as an antidepressant adjunct; standalone effect in healthy people unclear.
- Swardfager W, Herrmann N, Mazereeuw G, Goldberger K, Harimoto T, Lanctôt KL (2013). Biological Psychiatry, 74(12):872–878Lower serum zinc in depression; association, not causation.
- Donig A, Hautzinger M (2022). Nutritional Neuroscience, 25(9):1785–1795Zinc improved depression scores as an antidepressant add-on; preliminary.
Grades and studied doses are our conservative reading of the human research, shown for education. They are not product claims, and a studied dose is not a recommended dose.
See how Zinc compares on grade, dose, and goal in the Evidence Explorer.
