Zinc
An essential trace mineral, long taken at the first sign of a cold.
- Colds and infections
- Blood sugar
- Period pain
- Bone density
- Children's diarrhoea and growth
- Pregnancy
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
On this page
What is zinc?
Zinc is a trace mineral the body needs in small amounts and takes in from food. It sits inside about a tenth of the body’s proteins, holding enzymes and gene-reading proteins in shape, and has a hand in growth, in development and in how the immune system responds. Being short of it is common: poor nutrition is the main cause, and in some countries a quarter of people are affected, though age and illness leave people short elsewhere too. As a supplement it is always bound to a partner, such as picolinate, citrate, gluconate, glycine, oxide or sulphate, and it has long been taken for colds.
Why do people take zinc?
Colds and infections
The thinking. Zinc takes part in both the fast, front-line immune response and the slower, learned one, and going short leaves those defences working less well. Fifty years of laboratory work shows it acting directly against a range of viruses, which is where taking it for colds and cold sores comes from.
What research has found. The trials we have are from the coronavirus pandemic rather than the common cold. Adults given zinc alone, or added to usual care, mostly showed no clear difference in how long symptoms lasted; one trial did report fewer intensive care admissions and shorter hospital stays. Research here is still young: a few studies so far, mostly pointing the same way.
Blood sugar
The thinking. Zinc has a hand in how insulin is made, stored and signalled, and low zinc levels turn up more often in people with diabetes. Some adults with diabetes or prediabetes take it, the idea being that topping up might steady how the body handles sugar.
What research has found. Four reviews pooled randomised trials, mostly in adults with diabetes or prediabetes, and found small average falls in fasting blood glucose, glycated haemoglobin and insulin resistance: about 0.2 mmol/L of fasting glucose across trials covering nearly 4,000 people. Doses under 25 mg a day did as well as larger ones. This is one of the best-studied uses, and several reviews of trials broadly agree.
Period pain
The thinking. Zinc has a hand in hormone release, in reproduction and in the body’s inflammatory response, which is the idea behind taking it in the days before and during a period. Attention turned to it for period pain, polycystic ovary syndrome and endometriosis only lately.
What research has found. One review drew together 36 randomised trials in women of reproductive age and after the menopause. Taking zinc before and through each cycle went with less intense period pain; in women with polycystic ovary syndrome, what shifted was mostly tied to insulin and blood fats. Only a few studies have measured this so far, though they mostly agree.
Bone density
The thinking. Zinc plays a part in building bone and keeping it in repair, and blood zinc tends to run lower in people whose bones have thinned. Diets short of zinc also turn up more often among people who have broken a bone.
What research has found. One review brought blood levels, diets and supplement trials together. In the trials that gave zinc, bone density at the hip and the lower spine came out higher than in the comparison groups, and a blood marker for bone being built moved with it. This is early work, a small number of studies, mostly pointing the same way.
Children's diarrhoea and growth
The thinking. Zinc is needed for growth and for the defences that meet gut infections, and children short of it fall ill most. Where deficiency and poor nutrition are widespread it is given during a bout of diarrhoea, on World Health Organization advice.
What research has found. Two large reviews of trials in children found bouts of diarrhoea about half a day shorter in children over six months, nearer a day in undernourished ones, and no clear change under six months. The larger, covering over 200,000 children, also found a very small gain in height, but no difference in deaths or chest infections, and more vomiting than on placebo. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.
Pregnancy
The thinking. Low zinc in pregnancy has been linked with longer labours, raised blood pressure and babies arriving early, though the review that gathered those links says most are not settled. Taking it through pregnancy has been tested mostly among women on low incomes.
What research has found. One review of 21 randomised trials, covering over 17,000 women and their babies, found births before term around 14 per cent less common in the zinc groups, a difference carried mainly by trials among women on low incomes; birthweight and the other main outcomes were no different. The studies disagree, so this is unsettled: dose, duration and who took part all seem to shift the result.
What does zinc do in the body?
Zinc does not work like a fuel or a drug: it works by being there. Around a tenth of the body’s proteins have a zinc atom built into them, where it either holds a shape together or lets an enzyme do its chemistry. One large family, the zinc fingers, grip DNA and RNA and help settle which genes are read.
Because so much rests on it, the body keeps zinc on a tight rein: two families of transporter proteins carry it in and out of cells and park it where it is wanted. Zinc also damps down the master switch for inflammation, prompts the body to make the small proteins that mop up reactive molecules, and can stand in for iron and copper where those metals would otherwise do damage.
What do people say about taking zinc?
These are anecdotes people have shared, not evidence.
What people like
- Very commonly, fewer colds over the winter, or shorter and milder ones; most take it daily from autumn onwards, usually next to vitamin C.
- Skin is the other frequent reason for staying with it: spots and rosacea settling over a few weeks.
- Some people were put on it after a blood test came back low, and those posts describe the clearest change of all.
- A few mention their sense of taste returning after medication had dulled it.
- A small number of parents give it to a child and say they see a difference in concentration.
Common complaints
- Feeling sick is far and away the commonest complaint, and in a good number of posts actual vomiting within an hour of the tablet.
- An empty stomach is what people blame most often, though a minority say it turns their stomach whatever they eat with it.
- Stronger tablets, around 50 mg, draw most of the complaints; several dropped to a smaller dose so they could carry on.
- Several say plainly that they cannot tell what the zinc itself did, having changed diet, skincare or other supplements at the same time.
How people take it
- Almost everyone’s first piece of advice is to take it with a meal; some take it last thing at night, again with food.
- The doses described sit mostly between 30 mg and 50 mg a day, and 30 mg is where people settle after a bigger tablet proved too much.
- Form comes up mainly in connection with the stomach: gluconate is what most seem to have, picolinate the one suggested as easier to get on with.
- Plenty take it inside a multivitamin, or paired with vitamin C, rather than on its own; parents crush a tablet into juice for a child.
Read from these public discussions:
- Does anyone take Zinc supplements/ If so what for & are there any side effects? (Mumsnet, 2014)
- Keep getting colds - how do I avoid this? Give me your tips! (Mumsnet, 2022)
- To ask if you take any supplements and if so what difference have they made? (Mumsnet, 2026)
- Need advice on getting zinc into a child without causing nausea (Mumsnet, 2007)
- Zinc Making Me Nauseous (Acne.org community forum, 2013)
- Vomiting after taking Zinc? (Sherdog forums, 2007)
What forms of zinc are there?
| Form | What’s different | Elemental zinc by weight | Per serving, on products we list |
|---|---|---|---|
| Picolinate | Zinc bound to picolinic acid. | about 21.1 % | not in our price tables yet |
| Citrate | Zinc bound to citric acid. | about 32.1 % | 15 mg to 25 mg |
| Gluconate | Zinc bound to gluconic acid. | about 14.3 % | 25 mg |
| Bisglycinate | Zinc bound to two molecules of the amino acid glycine. | about 30.6 % | not in our price tables yet |
| Oxide | Zinc bound to oxygen. | about 80.3 % | not in our price tables yet |
| Sulphate | Zinc bound to sulphate. | about 36.4 % | not in our price tables yet |
| Other forms | Acetate, methionine, orotate, a blend, or a form the label does not name. | stated on the label | 6 mg to 15 mg |
What else is worth knowing about zinc?
- Labels give the elemental zinc per serving, and a serving may be more than one capsule; the partner it is bound to decides how much of a tablet’s weight is zinc.
- Vomiting was the side effect the children’s trials reported most, and the largest of those reviews also found copper status lower on zinc.
- The blood-sugar reviews split doses at 25 mg a day and found the lower ones did as well; one coronavirus trial used 50 mg a day for ten days.
- Most of the children’s and pregnancy trials were run where zinc deficiency and poor nutrition are widespread.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (20 studies)
- Zinc and selenium supplementation in COVID-19 prevention and treatment: a systematic review of the experimental studies. (2022, systematic review)
- Twice-Daily Oral Zinc in the Treatment of Patients With Coronavirus Disease 2019: A Randomized Double-Blind Controlled Trial. (2023, randomised trial)
- Do Zinc Supplements Enhance the Clinical Efficacy of Hydroxychloroquine?: a Randomized, Multicenter Trial. (2021, randomised trial)
- Effect of High-Dose Zinc and Ascorbic Acid Supplementation vs Usual Care on Symptom Length and Reduction Among Ambulatory Patients With SARS-CoV-2 Infection: The COVID A to Z Randomized Clinical Trial. (2021, randomised trial)
- Effects of Zinc Supplementation on Glycemic Control, Insulin Resistance, Inflammation and Oxidative Stress in Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. (2026, meta-analysis)
- Effects of Dose and Duration of Zinc Interventions on Risk Factors for Type 2 Diabetes and Cardiovascular Disease: A Systematic Review and Meta-Analysis. (2021, meta-analysis)
- Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trials. (2019, meta-analysis)
- Zinc and glycemic control: a meta-analysis of randomised placebo controlled supplementation trials in humans. (2013, meta-analysis)
- The effect of curcumin and zinc co-supplementation on glycemic parameters in overweight or obese prediabetic subjects: A phase 2 randomized, placebo-controlled trial with a multi-arm, parallel-group design. (2021, randomised trial)
- The Role of Zinc in Selected Female Reproductive System Disorders. (2020, systematic review)
- Is Zinc an Important Trace Element on Bone-Related Diseases and Complications? A Meta-analysis and Systematic Review from Serum Level, Dietary Intake, and Supplementation Aspects. (2021, meta-analysis)
- Oral zinc for treating diarrhoea in children. (2016, meta-analysis)
- Zinc supplementation for preventing mortality, morbidity, and growth failure in children aged 6 months to 12 years of age. (2014, meta-analysis)
- Zinc supplementation for improving pregnancy and infant outcome. (2015, meta-analysis)
- The Role of Zinc in Antiviral Immunity. (2019, review)
- Role of zinc in health and disease. (2024, review)
- Zinc as a Gatekeeper of Immune Function. (2017, review)
- Zinc status is associated with inflammation, oxidative stress, lipid, and glucose metabolism. (2018, review)
- Zinc: From Biological Functions to Therapeutic Potential. (2023, review)
- Zinc and its importance for human health: An integrative review. (2013, other)
How much does zinc cost?
That depends on the form and the pack, so we work out the price of the same dose of every zinc product we can find and rank them.