Zinc Supplements

Zinc has been claimed to reduce cold symptoms, help infants recover from infectious diseases, slow progression of age-related macular degeneration Age-Related Macular Degeneration (AMD or ARMD) Age-related macular degeneration (AMD) is the most common cause of irreversible central vision loss in older patients. Dilated funduscopic findings are diagnostic; color photographs, fluorescein... read more , and help wound healing.

Zinc has been suggested to increase insulin sensitivity.

Mild zinc deficiency impairs growth in children and can be corrected with zinc supplementation (1, 2 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ).

The US Food and Drug Administration (FDA) granted orphan drug designation to zinc acetate for treating Wilson disease Wilson Disease Wilson disease results in accumulation of copper in the liver and other organs. Hepatic or neurologic symptoms develop. Diagnosis is based on a low serum ceruloplasmin level, high urinary excretion... read more to prevent dangerous copper level elevation.

A 2013 Cochrane review of 16 therapeutic trials (1387 participants) and 2 preventive trials (394 participants) demonstrated that zinc reduced the duration (in days) but not the severity of common cold symptoms (3 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ). Although the proportion of participants with symptoms after 7 days of treatment was significantly smaller than those in the control groups, adverse effects, such as bad taste and nausea, were higher in the zinc group and should be taken into consideration (3 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ). A 2017 meta-analysis reported no difference in efficacy between zinc acetate and zinc gluconate lozenges in treatment of colds and no evidence for greater efficacy of daily doses higher than 100 mg (4 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ). Most studies have evaluated treatment rather than prevention of the common cold; however, a 2021 meta-analysis of 28 trials (5446 subjects) reported that, compared to placebo, zinc prevented 5 upper respiratory tract infections per 100 person months with a number needed to treat of 20 (5 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ). The study reported that symptoms resolved 2 days earlier compared to placebo and more subjects were likely to remain symptomatic after 7 days without zinc.

There is strong evidence that, in developing countries, supplements containing zinc 20 mg and 20 mg iron taken once a week, when given for the first 12 months of life, reduce infant mortality due to diarrhea and respiratory infections (6 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ). A 2016 Cochrane review found that zinc supplementation may be beneficial to treat diarrhea in zinc-deficient or malnourished children who are over 6 months old (7 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ).

There is also strong evidence that supplements containing zinc 40 to 80 mg and antioxidants (vitamin C and E and lutein/zeaxanthin) taken once/day slow progression of moderate to severe atrophic (dry form) age-related macular degeneration (8-9 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ).

Clinical data on zinc for treatment of diabetes are emerging. A 2019 systematic review and meta-analysis of 32 randomized placebo controlled trials (1700 subjects) using zinc monosupplements or with co-supplements in patients with prediabetes or diabetes, obesity or overweight, and pregnant women with prediabetes or diabetes, found a significant decrease in fasting glucose of 14 mg/dL (0.8 mmol/L) and hemoglobin A1C of 0.55% (10 References Zinc, a mineral, is required in small quantities (adult recommended dietary allowance of 8 to 11 mg/day) for multiple metabolic processes. Dietary sources include oysters, beef, and fortified... read more ). However, the hemoglobin A1C reduction with zinc monosupplement treatment was only 0.35%.

Zinc is generally safe, but toxicity can develop if high doses are used (see page Toxicity Zinc Toxicity Zinc (Zn) is contained mainly in bones, teeth, hair, skin, liver, muscle, leukocytes, and testes. Zinc is a component of several hundred enzymes, including many nicotinamide adenine dinucleotide... read more ). The common adverse effects of zinc lozenges include nausea, vomiting, diarrhea, mouth irritation, mouth sores, and bad taste.

Because zinc is a trace metal and can remove other necessary metals from the body, zinc lozenge dose should not exceed 75 mg per day (total dose, regardless of dosing frequency) for 14 days.

Zinc sprays may cause nose and throat irritation, and intranasal forms may result in anosmia.

The absorption and effect of certain antibiotics (eg, cephalexin, tetracyclines, quinolones) may be diminished by the oral zinc supplements; therefore, zinc should be taken at least 2 hours before or 4 to 6 hours after the antibiotic.

Zinc may stimulate tumor cell production of metallothionein, which may inactivate cisplatin, chelate integrase inhibitors (dolutegravir), and also decrease penicillamine levels by forming an insoluble complex.

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