What do the states mean?+
- Solid: well studied, and it works.
- Half-there: the science is still forming.
- A ghost: almost no real studies.
- Hollow: well studied, and it does not work.
- A cord: the pair itself has been tested together.
- Air: nobody has ever tested this pair.
The full scoring method: How we score
Zinc benefits: where the science stands
For immunity and colds: no.
Immunity and colds are what most people take zinc for, and the strongest evidence says it does not help: a combined review covering 34 trials found no real difference. As of August 2026, the verdicts on this page rest on evidence from 136 trials, drawn from the strongest research among the 6,942 papers on PubMed that mention zinc. Every claim is checked below.
6,942 papers on PubMed · evidence from 136 trials · 1 caution
Claim by claim
- Immunity and coldsWell studied, and it does not work. The biggest review covered 34 trials.
- Gut and digestionThe science is still forming. Results lean positive, but there is not much yet.
- MoodThe science is still forming. Results lean positive, but there is not much yet.
- Premenstrual symptomsAlmost no real studies. What exists leans positive.
See 2 more scored claims+
- Skin, hair and nailsThe science is still forming. Results lean positive, but there is not much yet.
- Stress and anxietyAlmost no real studies. What exists leans positive.
Pairs people ask about
The six sources we read
- 2024Meta-analysis · pools 34 trials, 8,526 people · no clear effect on immunity and coldssource
- 2024Meta-analysis · pools 38 trials · small benefit for gut and digestionsource
- 2024Meta-analysis · pools 49 trials · small benefit for skin, hair and nailssource
- 2024Observational study · small benefit for stress and anxietysource
- 2025Meta-analysis · large benefit for moodsource
- 2025Meta-analysis · pools 5 trials · moderate benefit for premenstrual symptomssource
Chosen as the strongest evidence out of 6,942 papers on PubMed. Every row links to its paper.
Fair questions
Does zinc work?+
For immunity and colds, the strongest evidence says no. The biggest review covered 34 trials.
Is zinc safe?+
One caution is recorded: Zinc taken for a cold probably causes more side effects than placebo: unpleasant taste, nausea, stomach cramps and diarrhoea were 34 percent more common across 16 treatment trials. The doses used in those trials, 45 to 276 mg a day, are far above the amount in a daily multivitamin.
Why only 6 sources, when PubMed lists 6,942?+
The 6,942 is every paper that mentions zinc in any way: animal studies, blood measurements, papers where it is a side note. The strongest sources are combined reviews, and each one already gathers every trial its authors could find. Our 6 cover 136 trials between them, and every one is linked above. Both counts are measured, not estimated.