Zinc
Zn, an essential trace mineral
A trace mineral the body needs for making new cells and enzymes, sold in supplements as salts such as zinc sulfate and gluconate. This page covers only studies in people that measured thinking, memory, mood, stress, sleep, energy, tiredness or quality of life, not all zinc research. In those, zinc is studied mostly for thinking and attention, often in children, and for mood alongside antidepressants. Here is every one we could find, sorted from each study's summary.
- Common forms: zinc sulfate and gluconate
- Most tested: 30 mg a day
- Mostly taken daily for weeks or months
From every paper to the studies that matter
Our search looked only at zinc papers on thinking, mood, sleep and energy, not at all zinc research. Most of those are lab or animal work, or only measure zinc in the blood or diet. A smaller share gives zinc to people, and that is what this page is about.
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12,607 papers on zinc and thinking, mood, sleep or energy.Every record in PubMed, all years
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376 are about people.The rest: 3,727 lab and animal studies, 2,115 reviews, 6,389 on chemistry, farming and more
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89 give zinc on its own.74 more give zinc with iron, vitamins or other nutrients, or in a blend
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56 are randomised against a placebo.Randomised controlled trials In a randomised controlled trial, people are put into groups by chance, one taking the treatment and one a placebo or other comparison. Chance spreads differences such as age and health evenly, so a difference between the groups is more likely to be down to the treatment., the strongest kind of study
Bar lengths use a square-root scale so the small numbers stay visible.
How much research there is
- 89 studies giving zinc to people, on thinking, mood, sleep and energy
- 56 of them randomised against a placebo A placebo-controlled trial compares a real treatment with a dummy that looks the same, the placebo. People often feel better when they expect to, so comparing against a placebo shows how much of the change comes from the treatment itself.
- 16,286 people taking part, where studies say
- 178 systematic reviews A systematic review searches for every study on a question in a set, written-down way, judges the quality of each and sums up what they show together. Many include a meta-analysis. The Atlas lists these as pooled reviews. pooling the trials
Studies in people, by year published
Zinc on its own, nearly always by mouth.
What the studies looked at
Each study can measure several things. Choose a topic to see its studies in the list below.
Studies in people with a diagnosed condition are counted here and listed with their population. We describe what they measured, not what they might treat. Most studies also report safety; see below.
What was tested, and how much
Most doses here are the elemental zinc a day, which is what compares from one study to the next. Some summaries give only the weight of the salt, such as 220 mg of zinc sulfate, which holds far less zinc itself, so the highest dots may not be higher doses at all. Many summaries don't name the form, and studies in babies and young children often used small doses. Most studies gave zinc every day for weeks or months.
Daily amount, one dot per study
Studies per extract
Named extracts are the maker's brand. "Not named" means the study didn't say.
All studies in people
Filter the list, then open a study on PubMed. Each row comes from the study's published summary, and about half follow children, many with low zinc, poor growth or ADHD.
| Study | Who took part | People | Extract and daily dose | Length |
|---|---|---|---|---|
| Rezazadegan 2026RCT, placebo | Adults with irritable bowel syndrome | 84 | Zinc gluconate, 20 mg | 13 weeks |
| Rezazadegan 2026RCT, placebo | Adults with irritable bowel syndrome | 84 | Zinc gluconate, 20 mg | 13 weeks |
| Almansouri 2025Non-randomised controlled | Cirrhotic patients with minimal hepatic encephalopathy | 148 | Zinc sulfate | 12 weeks |
| Squitti 2025RCT, placebo | Adults with mild cognitive impairment | 48 | Elemental zinc, 135 mg | 24 weeks |
| Moriya 2024Single-arm or open-label | Autoimmune hepatitis patients on corticosteroids | 26 | Polaprezinc, 150 mg | 104 weeks |
| Matsuoka 2023Non-randomised controlled | Post-COVID-19 outpatients | 120 | Zinc acetate hydrate | 12 weeks |
| Ahmadi 2023RCT, placebo | Female students with premenstrual syndrome | 69 | Not named, 220 mg | 24 weeks |
| Amini 2023RCT, active or other control | Opioid use disorder patients on methadone | 68 | Not named | 13 weeks |
| de Vargas 2023RCT, placebo | Overweight or obese women aged 40 to 60 | 42 | Not named, 30 mg | 12 weeks |
| Aoki 2022Non-randomised controlled | Postpartum women after cesarean with anemia | 197 | Not named | – |
| Behrouzian 2022RCT, placebo | Patients with schizophrenia on antipsychotics | 88 | Zinc sulfate, 660 mg | 6 weeks |
| Perez 2022Single-arm or open-label | Patients with cancer or neurodegenerative disease | – | KLS-1 (64Zn aspartate) | 5 weeks |
| Thomas 2021RCT, active or other control | Outpatients with SARS-CoV-2 infection | 214 | Zinc gluconate, 50 mg | 1 weeks |
| Afzali 2021RCT, active or other control | Community-dwelling older adults | 150 | Not named, 30 mg | 10 weeks |
| Janyajirawong 2021RCT, placebo | Cirrhosis patients with minimal encephalopathy | 69 | Elemental zinc, 45 mg | 12 weeks |
| Yosaee 2020RCT, placebo | Obese adults with depressive symptoms | 140 | Zinc gluconate, 30 mg | 12 weeks |
| Jafari 2020RCT, placebo | Young women with premenstrual syndrome | 60 | Zinc gluconate, 30 mg | 12 weeks |
| Noorazar 2020RCT, active or other control | Children with ADHD on methylphenidate | 60 | Not named | 6 weeks |
| Jafari 2020RCT, placebo | Young women with premenstrual syndrome | 60 | Elemental zinc, 30 mg | 12 weeks |
| Sudfeld 2019RCT, placebo | Tanzanian children followed after infant zinc supplementation | 365 | Not named | – |
| El-Baz 2019Single-arm or open-label | Children with ADHD and zinc deficiency | 50 | Not named, 55 mg | 26 weeks |
| Meguid 2019Single-arm or open-label | Children with autism spectrum disorder | 30 | Not named | 12 weeks |
| Hinnouho 2018RCT, placebo | Laotian children aged 6-23 months | 512 | Zinc tablets, 7 mg | 36 weeks |
| Pitchik 2018RCT, placebo | Tanzanian children after prenatal zinc and vitamin A | 198 | Not named | – |
| Gholipour Baradari 2018RCT, placebo | ICU nurses | 54 | Zinc sulfate, 73 mg | 4 weeks |
| Locks 2017RCT, placebo | Tanzanian infants | 2,400 | Not named | – |
| Fard 2017RCT, placebo | Postpartum women | 99 | Zinc sulfate, 27 mg | 8 weeks |
| Ribeiro 2017RCT, placebo | Colorectal cancer patients on chemotherapy | 24 | Zinc capsules, 70 mg | 16 weeks |
| Salehi 2016RCT, placebo | Children with ADHD on methylphenidate | 150 | Zinc sulfate | 8 weeks |
| Mathur 2015RCT, active or other control | Preterm neonates | 100 | Not named | – |
| Solati 2015RCT, placebo | Overweight or obese adults | 50 | Zinc, 30 mg | 12 weeks |
| Roshanravan 2015RCT, placebo | Pregnant women with impaired glucose tolerance | 44 | Zinc gluconate, 30 mg | 8 weeks |
| Salari 2015RCT, placebo | Multiple sclerosis patients with depression | 43 | Zinc sulfate, 50 mg | 12 weeks |
| Mapar 2015RCT, placebo | Haemodialysis patients with itching | 40 | Zinc sulfate, 220 mg | 4 weeks |
| Ryan 2014RCT, placebo | Malawian children at risk of enteropathy | 234 | Zinc sulfate, 20 mg | 2 weeks |
| Kim 2014RCT, active or other control | Children with atopic dermatitis | 58 | Not named | 8 weeks |
| Ranjbar 2014RCT, placebo | Patients with major depression on SSRIs | 44 | Zinc sulfate, 25 mg | 12 weeks |
| Colombo 2014RCT, active or other control | Peruvian infants 6-18 months | – | Zinc sulfate, 10 mg | 52 weeks |
| Lima 2013RCT, placebo | Brazilian shantytown children | 167 | Not named | – |
| Ranjbar 2013RCT, placebo | Patients with major depression on SSRIs | 44 | Zinc, 25 mg | 12 weeks |
| de Moura 2013Single-arm or open-label | Schoolchildren aged 6-9 | 36 | Zinc, 5 mg | 13 weeks |
| Murray-Kolb 2012RCT, placebo | Nepalese children, follow-up at age 7 to 9 | 734 | Not named, 10 mg | 100 weeks |
| Mitter 2012RCT, active or other control | Shantytown children with low height-for-age | 213 | Not named, 11 mg | 52 weeks |
| Gu 2012Crossover, placebo | Healthy volunteers wearing dental appliance | 9 | Zinc chlorideOn the skin | 1 weeks |
| Pongcharoen 2011RCT, placebo | Thai children followed up at age 9 | 560 | Not named | 26 weeks |
| Stewart-Knox 2011RCT, placebo | Healthy older Europeans | 387 | Zinc gluconate, 30 mg | 26 weeks |
| Siegel 2011RCT, placebo | Nepali infants | 367 | Not named, 5 mg | – |
| Arnold 2011RCT, placebo | Children with ADHD | 52 | Zinc glycinate, 30 mg | 13 weeks |
| Zamora 2011RCT, placebo | Children with ADHD on methylphenidate | 40 | Zinc sulfate, 10 mg | 6 weeks |
| DiGirolamo 2010RCT, placebo | Guatemalan school children | 674 | Zinc oxide, 10 mg | 26 weeks |
| Caulfield 2010RCT, active or other control | Peruvian children after prenatal supplementation | 184 | Not named, 25 mg | – |
| Siwek 2010RCT, placebo | Adults with major depression on imipramine | 60 | Not named | 12 weeks |
| Sawada 2010RCT, placebo | Young women, zinc added to multivitamin | 30 | Not named, 7 mg | 10 weeks |
| Kordas 2009RCT, placebo | Infants in Nepal and Zanzibar | 1,444 | Not named | 52 weeks |
| Uçkardeş 2009RCT, placebo | Low-income Turkish primary school children | 226 | Not named, 15 mg | 10 weeks |
| Tupe 2009RCT, active or other control | Indian schoolgirls | 180 | Ayurvedic zinc tablet (jasad bhasma) | 10 weeks |
| Siwek 2009RCT, placebo | Adults with major depression on imipramine | 60 | Not named, 25 mg | 12 weeks |
| Marcellini 2008Single-arm or open-label | Healthy elderly subjects | – | Not named | – |
| Rico 2006RCT, placebo | Lead-exposed Mexican schoolchildren | 602 | Not named, 30 mg | 26 weeks |
| Maylor 2006RCT, placebo | Healthy older adults aged 55 to 87 | 387 | Not named, 30 mg | 26 weeks |
| Kordas 2005RCT, placebo | Lead-exposed Mexican first-grade children | 602 | Zinc oxide, 30 mg | 26 weeks |
| Heckmann 2005RCT, placebo | Adults with idiopathic dysgeusia | 50 | Zinc gluconate, 140 mg | – |
| Bilici 2004RCT, placebo | Children with ADHD | 400 | Zinc sulfate, 150 mg | 12 weeks |
| Black 2004RCT, placebo | SGA infants, low-income urban | 200 | Zinc sulfate, 5 mg | 34 weeks |
| Akhondzadeh 2004RCT, placebo | Children with ADHD on methylphenidate | 44 | Zinc sulfate, 15 mg | 6 weeks |
| Nielsen 2004Other | Postmenopausal women in metabolic unit | 28 | Not named, 53 mg | 13 weeks |
| Tamura 2003RCT, placebo | Children of zinc-supplemented pregnant women | 355 | Not named, 25 mg | – |
| Makonnen 2003RCT, placebo | Children with protein-energy malnutrition | 300 | Zinc sulfate, 10 mg | 13 weeks |
| Makonnen 2003RCT, placebo | Children with protein-energy malnutrition | 300 | Zinc sulfate, 10 mg | 13 weeks |
| Nowak 2003RCT, placebo | Depressed adults on antidepressants | 14 | Not named, 25 mg | 12 weeks |
| Hamadani 2001RCT, placebo | Bangladeshi infants | 301 | Not named, 5 mg | 22 weeks |
| Singh 1999Crossover, placebo | Eumenorrheic women runners | 10 | Not named, 25 mg | – |
| Ashworth 1998RCT, placebo | Low birth weight term infants | 205 | Not named, 5 mg | 8 weeks |
| Doherty 1998RCT, active or other control | Children with severe malnutrition | 141 | Not named | 13 weeks |
| Penland 1997RCT, active or other control | Urban Chinese first-grade children | 372 | Not named, 20 mg | 10 weeks |
| Potocnik 1997Single-arm or open-label | Alzheimer's disease patients | 6 | Not named, 30 mg | – |
| Shrivastava 1993Non-randomised controlled | Children with mild-moderate malnutrition | 60 | Not named, 6 mg | 13 weeks |
| Bonomini 1991Single-arm or open-label | Regular dialysis patients | – | Not named | 26 weeks |
| Brandão-Neto 1990Non-randomised controlled | Healthy young adults | 27 | Not named | – |
| Gibson 1989Non-randomised controlled | Short boys aged 5-7 | 60 | Zinc sulfate, 10 mg | 52 weeks |
| Atalay 1989Pharmacokinetic | Malnourished children and healthy controls | 37 | Not named, 22 mg | – |
| Khanum 1988RCT, active or other control | Children recovering from malnutrition | 60 | Not named, 50 mg | 3 weeks |
| Katz 1987RCT, placebo | Adolescents with anorexia nervosa | – | Not named, 50 mg | – |
| Golden 1981Single-arm or open-label | Children recovering from severe malnutrition | 16 | Zinc acetate | – |
| 1981Other | Patient with acrodermatitis enteropathica | – | Not named | – |
| Zetin 1980Crossover, placebo | Male hemodialysis patients | 10 | Zinc in dialysate, 0 mg | – |
| Patrick 1980Single-arm or open-label | Children recovering from malnutrition | – | Not named | – |
| 1980Other | Children with protein-energy malnutrition | – | Not named | – |
| Golden 1978RCT, placebo | Malnourished children, skin test | 10 | Topical zinc sulphateOn the skin | – |
What's known about safety
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In trials
A review of zinc trials for colds found nausea and a bad taste more often on zinc than on placebo. A UK zinc medicine lists stomach pain, indigestion, nausea and diarrhoea as side effects, and warns that taking zinc for a long time can lower copper levels, which can affect the blood and nerves.
Singh 2013, Cochrane review of 18 trials; Solvazinc summary of product characteristics (emc)
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In the UK
Zinc in permitted forms, such as sulfate, gluconate, acetate, citrate and picolinate, can be sold in food supplements. The NHS advises not taking more than 25 mg of zinc supplements a day unless a doctor advises it, and EFSA's upper limit for adults is 25 mg a day from all sources.
Directive 2002/46/EC Annex II as retained in UK law (legislation.gov.uk); NHS vitamins and minerals page; EFSA upper intake levels overview, Oct 2026
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Check first
Zinc can reduce how well some antibiotics are absorbed, such as tetracyclines and quinolones like ciprofloxacin, and it interacts with iron, penicillamine and trientine. Its safety in pregnancy as a medicine hasn't been established, and it passes into breast milk. Speak to a pharmacist or doctor first if you take any of these or either applies to you.
Solvazinc summary of product characteristics, sections 4.5 and 4.6 (emc), Oct 2026
Where these studies come from
We list every published study in people that gave zinc and measured thinking, memory, mood, stress, sleep, energy, tiredness or quality of life, as zinc sulfate, gluconate, acetate, picolinate, polaprezinc or zinc-L-carnosine. Zinc added to a medicine or usual care counts as zinc on its own; zinc given with iron and folic acid, vitamins or other nutrients counts as a blend. Studies that only measured zinc in the blood, hair or diet are left out, as are zinc oxide in dressings and dental products and zinc tracers for scans. This first version is built from each study's summary; full-paper checks come next.
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We search
PubMed, the world's main library of medical research, for every paper on L-theanine.
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We keep studies in people
Lab and animal work is counted but left out of the list, because it doesn't tell you what happens in people.
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We note the basics
Who took part, how many, how much and for how long, from each study's published summary. A second check corrects what the first read gets wrong.
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We read them in full
Results appear once we've read the whole paper and checked every number. The date at the top shows when this entry was last updated.
Download the study list
Every study in people as a spreadsheet, 89 rows, free to reuse with a link back.
Versions
Each update to the data gets a new version number, so you can tell what changed and when.
See every version
1.0 · 24 Oct 2026. First release. Every published study giving zinc to people that measured thinking, memory, mood, stress, sleep, energy or quality of life is listed from its summary. None is read in full yet.
