Home Ingredients Zinc Citrate
Immune Support

Zinc Citrate

Evidence Level
Limited
2 Clinical Trials
5 Documented Benefits
2/5 Evidence Score

Zinc citrate is zinc bound to citric acid, an inexpensive and widely used form that is about 31 percent zinc by weight. In the most rigorous comparison we found, a 2014 stable-isotope study in 15 fasting adults, about 61 percent of a 10 mg dose was absorbed from zinc citrate, the same as from zinc gluconate and more than from zinc oxide (about 50 percent); the study was supported by a company that makes both salts. It has not been compared with picolinate using a direct absorption measure. Zinc citrate is also used in some toothpastes and mouthwashes, a separate topical use. Typical products provide 15 to 30 mg of elemental zinc; keep total zinc at or under 40 mg a day unless a clinician advises more, since weeks of 50 mg or more can lower copper.

Studied Dose 15 to 30 mg elemental zinc per day is the usual supplement range; the adult upper limit is 40 mg per day.
Active Compound Zinc citrate

Benefits

Absorbed as Well as Gluconate

In a randomized, double-masked crossover study using stable isotope tracers, 15 healthy fasting adults absorbed 61.3 percent of a 10 mg dose from zinc citrate, 60.9 percent from zinc gluconate and 49.9 percent from zinc oxide. The study was supported by Jungbunzlauer, which makes zinc citrate and zinc gluconate. It has not been compared with picolinate or bisglycinate this way.

Supported by Trial 1

Used in Toothpaste and Mouthwash (Topical, Not Swallowed)

Zinc citrate is added to some toothpastes, mouthwashes and chewing gums, where zinc acts on bacteria in the mouth. That is a topical use: the product is used in the mouth and spat out. It is not evidence for what a swallowed zinc citrate supplement does, and no toothpaste or mouthwash trial is cited anywhere on this page.

Supported by Trial 2

Toothpaste Research on Plaque and Gum Inflammation

Toothpastes and mouthwashes containing zinc citrate have been reported to modestly reduce dental plaque and gum inflammation, often alongside other active ingredients such as stannous fluoride. None of those trials is cited on this page, and every one of them tested a product used in the mouth rather than a supplement you swallow, so they say nothing about taking zinc citrate capsules.

Supported by Trial 2

Immune Support

Zinc is required for normal immune cell function. The one study cited here is a 2020 review of 10 randomized trials in which zinc supplements shortened the common cold by about 2.25 days on average (95 percent confidence interval 1.12 to 3.39 days shorter). Those trials used zinc in general, not zinc citrate specifically, and they were about shortening an existing infection, not about preventing illness in a healthy person.

Supported by Trial 2, Trial 1

Zinc's Role in Skin (Not Tested Here)

Zinc is a nutrient the skin needs for normal barrier repair. No study cited on this page tested zinc citrate for acne or any other skin outcome, so this is background about zinc as a nutrient rather than evidence that a zinc citrate capsule clears acne.

Supported by Trial 2

Mechanism of action

1

Citrate Solubilization

Zinc citrate is only slightly soluble in water, yet in a tracer study it was absorbed as well as the more soluble zinc gluconate. The exact reason is not established.

2

Antimicrobial Action

Zinc ions interfere with bacterial enzymes and cell membranes, which is why zinc is added to toothpaste and mouthwash. This describes zinc released into saliva by a product held in the mouth. A capsule that is swallowed does not deliver zinc to the mouth this way.

3

Volatile Sulfur Compound (VSC) Reduction

Zinc binds the sulfur compounds that cause bad breath, which is how zinc-containing rinses, gums and toothpastes freshen breath. This only applies to products used in the mouth, not to a swallowed zinc citrate capsule.

4

Standard Zinc Enzyme Cofactor Function

Zinc is a helper mineral for hundreds of enzymes in the body, it helps proteins that switch genes on and off hold their shape, and it is part of one of the body's own antioxidant enzymes. This is true of zinc from any source, not of zinc citrate in particular.

Clinical trials

1
Zinc Citrate Absorption: Wegmüller 2014
PubMed

Randomized, double-masked, three-way crossover study measuring fractional zinc absorption with stable isotope tracers after a 10 mg dose taken fasting. (Wegmüller et al. 2014, Journal of Nutrition)

15 healthy young adults in Switzerland.

Absorption was 61.3 percent from zinc citrate, 60.9 percent from zinc gluconate and 49.9 percent from zinc oxide; the oxide difference was significant only when three participants who absorbed little oxide were included. Supported by Jungbunzlauer, a maker of zinc citrate and gluconate.

2
Zinc Citrate Toothpaste for Plaque and Gum Inflammation (Toothpaste, Not a Supplement)

Toothpaste trials, in which the product is brushed and spat out rather than swallowed. No specific trial is cited on this page, so the number of people, the doses and the study lengths cannot be checked.

Adults with plaque/gingivitis.

Zinc citrate toothpastes are reported to modestly reduce plaque and gum bleeding compared with a control toothpaste, and to be less effective than prescription antiseptic rinses. These are results for a product used in the mouth and say nothing about what swallowing a zinc citrate capsule does.

Side effects and drug interactions

Common Potential side effects

Generally well-tolerated.
Mild GI distress at high doses.
Metallic taste.
Toothpaste/mouthwash forms: staining is possible in theory at high concentrations.
Copper deficiency with long-term high intake. The adult upper limit is 40 mg of elemental zinc per day from all sources; do not exceed it long term without medical supervision.

Important Drug interactions

Quinolone and tetracycline antibiotics: zinc binds them; NIH advises taking the antibiotic at least 2 hours before or 4 to 6 hours after zinc.
Bisphosphonates: take them as the label directs, and take zinc at a different time.
Penicillamine: zinc can reduce its effect; keep them at least 1 hour apart and ask the prescriber.
Iron: iron supplements of 25 mg or more taken at the same time can lower zinc absorption; take them apart.
Calcium: high-dose calcium may reduce zinc absorption.

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Frequently asked questions about Zinc Citrate

What is zinc citrate?

Zinc citrate is zinc bound to citric acid. It has a fairly neutral taste and is a common, inexpensive form used in supplements and in some toothpastes. In a tracer study it was absorbed as well as zinc gluconate and better than zinc oxide.

Is zinc citrate well absorbed?

Yes. In a 2014 stable-isotope study in 15 fasting adults, about 61 percent of a 10 mg dose was absorbed from zinc citrate, the same as from gluconate and more than from oxide (about 50 percent). It has not been compared with picolinate using a direct absorption measure.

How much zinc citrate should I take?

Doses commonly provide 15 to 30 mg of elemental zinc per day. Avoid exceeding about 40 mg daily long-term without medical advice, since chronic high zinc can deplete copper. Check the label for elemental zinc.

When should I take zinc citrate?

Take it with a little food if needed to avoid nausea, and away from calcium, iron, and coffee, which reduce absorption. Once daily is typical.

What is Zinc Citrate used for?

Zinc Citrate is researched primarily for Immune Support. In a randomized, double-masked crossover study using stable isotope tracers, 15 healthy fasting adults absorbed 61.3 percent of a 10 mg dose from zinc citrate, 60.9 percent from zinc gluconate and 49.9 percent from zinc oxide.

Is Zinc Citrate safe, and does it have side effects?

Side effects and cautions reported for Zinc Citrate include: Generally well-tolerated. Mild GI distress at high doses. It may also interact with some medications. Zinc Citrate is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Zinc Citrate interact with any medications?

Possible interactions include: Quinolone and tetracycline antibiotics: zinc binds them; NIH advises taking the antibiotic at least 2 hours before or 4 to 6 hours after zinc. Bisphosphonates: take them as the label directs, and take zinc at a different time. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Zinc Citrate?

NutraSmarts rates the evidence for Zinc Citrate as Limited (2 out of 5). It is backed by 2 study summaries and 1 cited reference summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(1 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Wang MX, Win SS, Pang J. Zinc Supplementation Reduces Common Cold Duration among Healthy Adults: A Systematic Review of Randomized Controlled Trials with Micronutrients Supplementation. Am J Trop Med Hyg. 2020;103(1):86-99..PubMedUsed to support: Systematic review pooling 10 randomized trials of zinc supplements, which shortened common cold duration by about 2.25 days (95 percent confidence interval 1.12 to 3.39 days). It pooled zinc in general and did not test zinc citrate or any specific zinc salt.