Check a label

Ingredient

Zinc

Research dose

11 mg/day

Moderate Trials gave zinc daily, for weeks: what counts is the amount you take in a day.

Judged against the RDA, 11 mg a day for men (8 mg for women), and the US upper limit of 40 mg a day, set to protect copper status (the EU's is 25 mg). Studies have used more for set periods (45 mg a day for a year in older adults; 80–92 mg a day as cold lozenges), but a page never counts going past the upper limit as a target.

Upper reference: 40 mg per serving. One serving at or above it is marked “too much”.

Sources

  1. Schoofs H, Schmit J, Rink L. Zinc toxicity: understanding the limits. Molecules. 2024;29(13):3130.

    Supports the research dose. Where: Section 2: "the recommended dietary allowance (RDA) for zinc intake states that 11 mg/day for men and 8 mg/day for women are sufficient". Read the source, checked 9 Oct 2026.

  2. Schoofs H, Schmit J, Rink L. Zinc toxicity: understanding the limits. Molecules. 2024;29(13):3130.

    Supports the upper reference. Where: Abstract: "The European Food Safety Authority (EFSA) defines the tolerable upper intake level (UL) as 25 mg per day, whereas the Food and Drug Administration (FDA) allows 40 mg per day"; body: "Beyond this threshold, there is a risk of impairing copper homeostasis". Read the source, checked 9 Oct 2026.

Zinc supplements we've checked

12 zinc supplements, each judged on how much a day its label's own directions give. See them all, ranked.

Why the 40 mg limit, and what studies used

Too much zinc lowers copper. In healthy men, 50 mg of zinc a day (two doses of 25 mg) for 6 weeks lowered a marker of copper status (Fischer et al., 1984). The US upper limit of 40 mg a day counts all zinc, from food, multivitamins and lozenges as well; the EU's is 25 mg (Schoofs et al., 2024).

Some trials used more for a set time and under study conditions: 45 mg a day for a year in older adults (Prasad et al., 2007), and 80–92 mg a day as lozenges for a few days during a cold (Hemilä, 2017). Those are why some products sell 50 mg, but a page here never counts going past the upper limit as a target.

Research context, not advice.