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Zinc

Zinc is an essential mineral involved in numerous enzymes. It plays a role in antioxidant enzymes, brain function, and the immune system, among many other biological roles. Zinc is most commonly taken to reduce the frequency of illness and to support optimal levels of testosterone.

Our evidence-based analysis on zinc features 386 unique references to scientific papers.

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NOTE: We are updating our coronavirus (COVID-19) page with evidence as it comes in.

Summary of Zinc

Primary information, health benefits, side effects, usage, and other important details

It is invalid to extrapolate from efficacy against the common cold or respiratory tract infections broadly to the novel coronavirus in particular. For more information, see our page on COVID-19.

What is zinc?

Zinc is an essential dietary mineral that has numerous roles in the body, most notably as a catalytic and structural element in hundreds of metalloproteins. Meat, egg, and legume products are common sources. Oysters are particularly good sources of zinc.

What are zinc’s benefits?

Any benefits of oral zinc supplements or increased dietary intake will depend on the zinc status of the individual. Some research suggests that when zinc levels are low, insulin sensitivity and testosterone can decrease, and supplementation can bring levels closer to normal.

Zinc lozenges, in high doses, seem to reduce the duration of common colds, though it's unclear if they reduce the risk of getting colds in the first place or the severity of symptoms. Their effects are largely limited to throat and nasal symptoms, and high doses tend to come with some mild but notable side-effects like nausea and metallic taste in the mouth. Zinc lozenges have not been studied for COVID-19 and extrapolation from colds to COVID-19 is invalid. For more information, see this page.

Other areas of note are depression and acne, which can frequently benefit from increased zinc intake if levels are low.

Zinc is lost through sweat, making supplementation very important for athletes that don’t get a lot of zinc through food. Insulin resistance can also decrease zinc levels.

What are zinc’s side effects and drawbacks?

Large doses of zinc can produce nausea and other forms of gastrointestinal upset, particularly when taken on an empty stomach. Large doses of zinc can also cause a copper deficiency and lead to overdose. Many supplements use far more than the RDA, and a combination of supplements, fortified foods, and high zinc foods may lead to exceeding the tolerable upper intake level for adults, which is 40 mg per day. High dose zinc lozenges can lead to nausea and a metallic taste in the mouth, and should only be taken for a short time, if at all.

What problems does a zinc deficiency cause?

Zinc deficiency in childhood can impair growth. In adults, zinc deficiency can result in hypogonadism in men, as well as mental lethargy, depression, and skin abnormalities. Low levels of zinc due to diabetes can further worsen insulin resistance. It is estimated that inadequate zinc intake affects around 10% of persons in the US, but global insufficiency rates are over 50%.

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How to Take

Medical Disclaimer

Recommended dosage, active amounts, other details

Zinc has two standard dosages. The low dosage is 5-10mg, while the high dosage is 25-45mg. The low dose works well as a daily preventative, while the high dosage should be taken by anyone at risk for a zinc deficiency.

Different forms of zinc contain different amounts of elemental zinc, which refers to the weight of the zinc molecule by itself (Note: Product labels tend to mark the elemental weight)

  • Zinc citrate is approximately 34% zinc by weight. For a dose of 50mg elemental zinc, take 146 mg zinc citrate.

  • Zinc sulfate is approximately 22% zinc by weight. For a dose of 50mg elemental zinc, take 220 mg zinc sulfate.

  • Zinc gluconate is approximately 13% zinc by weight. For a dose of 50mg elemental zinc, take 385 mg zinc gluconate.

  • Zinc monomethionine is approximately 21% zinc by weight. For a dose of 50mg elemental zinc, take 238 mg zinc monomethionine.

Zinc should be supplemented daily.

Superloading zinc by taking up to 100mg zinc a day is confirmed to be safe in the short term (2-4 months), but because this dose is higher than the 40mg Tolerable Upper Limit (TUL) of zinc, prolonged superloading is not advised. Zinc’s intestinal uptake is hindered by other minerals, including calcium, magnesium, and iron, since they all use the same transporter. If the transporter’s uptake limit (800mg) is exceeding between these four minerals, absorption rates will fall. Taking less than 800mg of these four minerals at the same time is fine.

Zinc lozenges, for the purpose of reducing the common cold, seem to be most effective when the total daily dose is over 75 mg and is divided into 6-8 doses, each separated by 2-3 hours when awake. It is likely dangerous to take zinc lozenges for extended periods of time.

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Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects zinc has on your body, and how strong these effects are.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b Notable Very High See all 5 studies
The reduction in depression is notable only for treatment resistant depression alongside a pharmaceutical antidepressant; there does not appear to be a benefit to persons who respond to antidepressants and the inherent anti-depressant effects without a pharmaceutical add-on are modest at best.
grade-b Minor Very High See all 4 studies
Orally supplemented zinc (in the dosage range of 30-130mg elemental zinc) appears to be effective in reducing symptoms of acne, although the effects are modest at best.
grade-b Minor High See all 3 studies
A reduction in blood glucose has been observed alongside improvements in insulin sensitivity in obese persons who may have been zinc deficient.
grade-b Minor High See all 5 studies
Supplementation of zinc in persons who may be zinc deficient is able to reduce C-reactive protein
grade-b Minor High See all 3 studies
There is an increase in IGF-1 concentrations if the subject is deficient in zinc, but no increase otherwise.
grade-b Minor High See all 4 studies
Basal insulin concentrations appear to be reduced following supplementation of zinc.
grade-b Minor Low See all 3 studies
A decrease in LDL cholesterol may occur when a zinc deficiency in obese persons is being normalized.
grade-b Minor Very High See all 13 studies
Zinc lozenges, particularly over 75 mg per day (taken in divided doses roughly every 2 hours while awake), and particularly from zinc acetate, have evidence for a small-moderate reduction in the duration of common colds. While evidence points to high dose zinc acetate as the most effective, this is from comparisons between different studies, and as such, isn't as strong as head-to-head comparisons. More research is needed to confirm the most effective method of zinc lozenge use.
grade-b Minor Very High See all 3 studies
A slight decrease in lipid peroxidation has been noted with supplementation of zinc in persons who may be deficient.
grade-b Minor Moderate See all 4 studies
Decreases in the severity but not occurrence of mucositis have been reported in cancer patients undergoing both radiotherapy and chemotherapy, although the benefits seem unreliable
grade-b Minor Very High See all 11 studies
Zinc, particularly >75 mg daily of zinc acetate (more research is needed to confirm the best form and dose) reduces the duration of common colds, and so the time that symptoms are present. It likely has a small effect on the severity of throat and nasal symptoms at any given time, but is less likely to help with headache or fatigue.
grade-b Minor High See all 5 studies
Both chronic/excessive exercise as well as a zinc deficiency are associated with abnormally low testosterone concentrations, and in these states supplementation of zinc increases testosterone. There is no inherent increase in testosterone with zinc if either of those two conditions are not met
grade-b - Very High See all 8 studies
In regards to pneumonia in particular, zinc does not appear to have any appreciable benefit either when superloaded by itself or taken as an adjuvant alongside antibiotics
grade-c Notable - See study
Topical application of a 0.25% zinc pyrithione cream is associated with highly significant reductions in psoriasis symptoms (twice daily application for three months reducing them by over 70%)
grade-c Notable Very High See all 3 studies
Although the evidence is very preliminary right now, supplementation of high dose zinc (up to 132mg elemental zinc) is able to abolish viral warts by 50-60% while topical application (10% zinc sulphate solution) can abolish viral warts in 80% of persons. Nonviral warts have less of a response to treatment.
grade-c Minor - See study
Secondary to an improvement in overall mood, aggressive symptoms have been noted to be reduced with low dose zinc supplementation.
grade-c Minor Very High See 2 studies
There appears to be an increase in superoxide dismutase and glutathione peroxidase after supplementation of zinc in otherwise healthy persons.
grade-c Minor - See study
A slight increase in apolipoprotein A has been reported in obese persons who may have been zinc deficient, but then supplemented to alleviate said deficiency.
grade-c Minor - See study
Apolipoprotein B may be abnormally elevated during zinc deficiency as it is reduced upon supplementation of zinc.
grade-c Minor - See study
In persons who were probably zinc deficient, supplementation of zinc is able to reduce cellular adhesion factors and the risk for artherosclerosis.
grade-c Minor Very High See 2 studies
An improvement in cognition has been seen in stroke patients given zinc to complement their zinc insufficient diet.
grade-c Minor - See study
An increase in DHT has been noted in infertile men
grade-c Minor - See study
Supplementation of zinc in children who were probably deficient is able to reduce the formation of plaque and is thought to then reduce risk of dental cavities; gingivitis risk was not affected.
grade-c Minor Moderate See all 3 studies
Although there may be an improvement in symptoms of persons who are specifically deficient in carbonic anhydrase VI (zinc dependent enzyme) which occurs with zinc deficiency, dysgeusia and hypogeusia associated with chemotherapy seem unaffected
grade-c Minor Moderate See 2 studies
Zinc can increase the fertility of men who are infertile and have low circulating testosterone, and appears ineffective in men who have normal testosterone levels with infertility. This is related to an increase in sperm count seen in the former group.
grade-c Minor Very High See 2 studies
Free testosterone follows the same trends as testosterone, and may be increased following supplementation in persons who are deficient in zinc
grade-c Minor - See study
An increase in functionality of elderly frail persons has been seen with zinc supplementation, thought to be related to the increase in IGF-1 also observed.
grade-c Minor Very High See 2 studies
An increase in insulin sensitivity has been noted with supplementation of zinc in insulin resistant persons who were likely zinc deficient.
grade-c Minor Moderate See 2 studies
Alongside other proinflammatory cytokines, IL-6 appears to be reduced following supplementation of zinc.
grade-c Minor Moderate See all 5 studies
Iron absorption is decreased when both iron and zinc exceed 10mg in a supplement given on an empty stomach. The inhibition does not appear to be relevant if the same ratio is at lower doses (500mcg) or if the minerals are ingested via food products.
grade-c
Minor
- See 2 studies
Normalizing a zinc deficiency increases leptin (which is suppressed during deficiency), but elsewhere the abnormal elevation of zinc seen in morbid obesity has been reduced alongside weight loss and insulin sensitization from zinc.
grade-c Minor - See study
Supplementation of zinc in persons with liver cirrhosis appears to be mildly therapeutic, possibly related to reducing hepatic copper concentrations.
grade-c Minor Moderate See 2 studies
Although there may not be an inherent protective effect and normalizing a deficiency does not per se reduce oxidation of LDL, if the body becomes more insulin sensitivity when restoring a deficiency then zinc may indirectly reduce oxidation.
grade-c Minor - See study
A slight decrease in reaction time has been noted in persons who are zinc deficient and then supplemented with zinc.
grade-c Minor Moderate See all 3 studies
Supplemental zinc (30mg) has been noted to increase serum BDNF in depressed subjects in one study, which did not occur in study; there were differences in the study demographic and more research is needed.
grade-c Minor Very High See 2 studies
The decline in T3 hormone levels during prolonged exercise is abolished with supplementation of zinc.
grade-c Minor Very High See 2 studies
The decline in T4 hormone levels during prolonged exercise is abolished with supplementation of zin
grade-c Minor High See all 9 studies
Studies overall support a small reduction in the severity of cold symptoms, though "small" should be stressed. It's unlikely that the average person will see dramatically diminished cold symptoms if they have them. The symptoms largely derive from reductions in nasal symptoms including discharge and sneezing, and from cough. Indeed, zinc lozenges seem to target viruses in the upper respiratory tract, but are unlikely to reduce headache, fatigue, or fever.
grade-c Minor Moderate See 2 studies
An increase in sperm count has been noted in infertile men who also had low testosterone; it was ineffective in infertile men with normal testosterone
grade-c Minor - See study
In zinc deficient persons who recently suffered a stroke, supplementation of zinc appears to accelerate the rate of recovery.
grade-c Minor Moderate See 2 studies
Although the evidence is mixed currently, zinc has been previously associated with an improvement in mood state and has mechanisms by which it can work. It likely has a small but positive influence.
grade-c Minor - See study
High dose zinc (220mg twice daily) may have a minor additive role to standard OCD therapy (fluoxetine), although the small magnitude of benefit and the high dose used suggest that it is not the best supplemental option.
grade-c Minor - See study
High dose (440mg) zinc sulphate appears to be effective in hemodialysis patients in reducing pruritis.
grade-c Minor - See study
Zinc supplementation at higher levels (50mg) appears to be able to reduce subjective symptoms of tinnitus in most persons supplemented with zinc.
grade-c Minor - See 2 studies
A zinc deficiency is associated with reduced circulatin TNF-a concentrations, which are normalized upon zinc sufficiency.
grade-c Minor Moderate See 2 studies
A decrease in cholesterol, due to LDL-C being reduced, seems to occur following oral supplementation of zinc in persons who are obese and likely zinc deficient
grade-c Minor Moderate See 2 studies
In children who are likely deficiency, zinc supplementation can reduce body weight.
grade-c - - See study
No significant influence of zinc supplementation on symptoms of ADHD in children.
grade-c - - See study
Blood flow does not appear to be modified with supplementation of zinc.
grade-c - - See study
Blood pressure does not appear to be modified with zinc supplementation.
grade-c - - See study
No significant interaction with biomarkers of general oxidation
grade-c - Very High See 2 studies
No significant influence on HDL-C, even when normalizing a zinc deficiency associated with weight loss.
grade-c - - See study
No significant influence of zinc supplementation on plasma nitrate or nitrite levels, suggesting no interaction with nitric oxide metabolism
grade-c Very High See all 3 studies
There seems to be a reduction in the risk of developing upper respiratory tract infections when it's taken as a prophylactic, however, this largely derives from one study on natural colds, while two on experimentally induced rhinoviruses didn't have a notable reduction.
grade-c - Moderate See 2 studies
Although efficacy cannot yet be ruled out, the best evidence currently does not support a role for zinc supplementation in the treatment of rosacea
grade-c - Very High See 2 studies
No significant reduction in circulating triglycerides has been detected with zinc supplementation.
grade-c - - See all 3 studies
There seems to be a reduction in the risk of developing upper respiratory tract infections when it's taken as a prophylactic, however, this largely derives from one study on natural colds, while two on experimentally induced rhinoviruses didn't have a notable reduction.
grade-d Minor - See study
One study found an improvement in women with PMS. This might not translate to other cases, and much more research is needed.
grade-d Minor - See study
One study found an improvement in women with PMS. This might not translate to other cases, and much more research is needed.
grade-d Minor - See study
One study found an improvement in women with PMS. This might not translate to other cases, and much more research is needed.
grade-d Minor - See study
Interleukin 2 (IL-2) appears to be reduced during zinc deficiency, and this is normalized upon zinc sufficiency.
grade-d Minor - See study
In persons who are deficient in zinc, an increase in LH occurs following zinc replenishment.
grade-d Minor Very High See 2 studies
Preliminary research suggests notable improvements in psychological symptoms, and possibly physical symptoms, but more detailed evaluation of specific physical symptoms is needed.
grade-d - - See study
grade-d - - See study
No known significant interactions with zinc supplementation on fat mass.
grade-d - - See study
No detectable influence of zinc supplementation of FSH concentrations in zinc deficient persons.
grade-d - - See study
No detectable increase in prolactin in persons who are deficient in zinc and then supplemented to restore levels.
grade-d - - See study
No significant influence on serum DHEA sulfate

Studies Excluded from Consideration

  • Confounded with the inclusion of Magnesium and vitamin B6 (used the formulation known as ZMA)[1]

  • Unavailable online. [2]

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Frequently Asked Questions and Articles on Zinc

5 nutrients that could lift your mood
Many foods can temporarily boost your mood simply because they’re delicious. But healthy foods also contain certain nutrients that may have a more direct and lasting effect on your well-being.
How can you increase testosterone naturally?
When it comes to increasing your testosterone, quality sleep, physical activity, and weight management come first. A few supplements can help sustain healthy testosterone levels, but most supplements marketed as testosterone boosters don’t work, though some can make you believe they do by boosting your libido.
Does ZMA cause weird dreams?
It is possible that ZMA can cause weird dreams, and the anecdotes support this; however, since this has not been directly investigated the best 'proof' that can be given is weak.

Things to Note

Primary Function:

Goes Well With

Caution Notice

Caution should be taken when using zinc supplementation surpassing the Tolerable Upper Limit of Intake (TUL) of 40mg, and if possible alternate supplements with better toxicology profiles should be used for those purposes desired.

  • Zinc is non-stimulatory

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