Zinc Supplements and Lozenges Review
Initial Posting: 10/6/17 Last Update:1/28/20
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What It Is:
- What is it? Zinc is an essential mineral, one of the few nutrients for which a mild deficiency is not uncommon. (see What It Is). Zinc is naturally found in meats and other foods (see Getting Zinc -- From Food)
- What does it do? Zinc supplements (typically taken in pill form) can reverse or prevent zinc deficiency (which can otherwise impair the immune system, cause diarrhea, reduce taste, etc.) and help slow advanced macular degeneration of the retina. Zinc is also taken as a lozenge (or other orally dissolving formulation) to act locally on the throat to reduce the duration of a cold. (See What It Does).
- How much to take, and which form? The daily requirement for zinc ranges from 3 mg for children to 14 mg for lactating women (see Dosage). No form is particularly better absorbed than another and zinc gluconate is typically the least expensive. To reduce the duration of a cold, take a lozenge (or other orally dissolving formulation providing 13.3 to 23 mg of zinc typically as zinc gluconate) every 2 hours during the day, allowing it to fully dissolve in the mouth: Limit treatment to a week because chronic intake of too much zinc (see upper intake levels) can reduce copper absorption, leading to copper deficiency that can impair the immune system.
- Best zinc? Among supplements that passed testing, we identified our Top Pick for Pills, Top Pick for Lozenges, and Top Pick for Other Orally Dissolving Formulations. We found that you can pay as little as 1 cent or more than $1 to get an equivalent dose of high quality zinc — there is no need to overspend.
- Cautions: As noted above, don't take too much zinc and don't take with fiber, which inhibits absorption of zinc. Be aware of drug interactions with zinc, particularly for certain antibiotics. (See Concerns and Cautions).
Zinc is an essential mineral, one of the few nutrients for which a number of people are mildly deficient. Zinc deficiency is especially common in adolescents, infants, seniors and women in general, although severe deficiency is rare in developed countries. Zinc deficiency can cause slowed growth in infants and children and impaired immune function. Deficiency has also been associated with recurrent aphthous stomatitis (canker sores) (Hamid, Int J Contemp Med Res 2017). Symptoms of severe deficiency can include hair loss, diarrhea, impotence, weight loss, delayed healing of wounds, taste abnormalities and loss of taste (NIH 2018; Schiffman, Eur J Clin Nutr 2000). Certain drugs and nutrients can inhibit zinc absorption and/or increase its excretion (see "Using Zinc," below). Thus, for many people, increasing the intake of zinc-containing foods or taking a zinc supplement, either alone or as part of a multivitamin/multimineral, may be a prudent form of nutritional insurance.
As a dietary supplement, zinc is found in many forms, including zinc gluconate, zinc acetate, zinc citrate, zinc sulfate, zinc chelates, zinc carbonate, zinc orotate, and zinc picolinate. (See ConsumerTips for information about the forms of zinc and foods that contain zinc.)
What It Does:
Zinc plays a role in brain function, wound healing, sperm production, and vision maintenance. Zinc in pill or liquid form may be taken in nutritional doses to replenish depleted zinc levels. What about lozenge? Is zinc from a lozenge absorbed?
In zinc deficiency
Among people who are deficient in zinc (especially the elderly), some evidence suggests that such replenishment might help increase immunity. Supplementation is particularly effective in reducing the duration and severity of diarrhea in zinc-deficient individuals. Correcting zinc deficiency (and iron deficiency, if also present) in people with recurrent canker sores was found to eliminate recurrence of sores (Yildirimyan, Oral Health Prev Dent 2019).
Most, although not all, studies have shown that zinc lozenges can reduce cold symptoms. Effectiveness appears to require a sufficient amount of zinc (9 to 13.3 mg) per lozenge, slow dissolution (15 to 30 minutes), and frequency of dosing (6 to 10 lozenges per day), as noted below.
A review of 3 randomized, placebo-controlled, double-blind clinical trials involving substantial total daily doses (80 mg to 92 mg) of zinc from lozenges (9 to 13.3 mg of zinc per lozenge) given within 24 hours of cold symptoms found that they shortened the duration of nasal discharge by 34%, nasal congestion by 37%, sneezing by 22%, scratchy throat by 33%, sore throat by 18%, hoarseness by 43%, and cough by 46%. Interestingly, muscle ache was also shortened by 54% but there was no difference in the duration of headache or fever. (Hemila, BMC Family Practice 2015). An subsequent analysis of seven clinical trials in which zinc lozenges were given within the first few days onset of a cold found that both zinc gluconate or zinc acetate worked equally as well in reducing the duration of colds, by an average of 33% (about 2 to 3 days) compared to placebo (Hemila, JMSR Open 2017). The study also found that lower daily doses of zinc (80 mg to 92 mg elemental zinc) were just as effective as higher daily doses (192 mg to 207 mg elemental zinc); all doses were divided, and taken as 6-10 lozenges per day. NOTE: Zinc at these high doses (all of which exceed the upper tolerable daily intake for zinc) should generally not be taken for much longer than one week.
A study in Finland among 87 men and women (average age 49) found that a zinc lozenge (containing 13 mg of zinc from zinc acetate) dissolved in the mouth five to six times daily during the first five days of a cold did not shorten the duration of colds compared to placebo. The researchers suggested that the lack of benefit may have been due to the fact that most participants used five rather than six lozenges per day (providing a daily total of 65 mg of zinc — a lower dose than used in other studies, as discussed above) and that the lozenges were smaller and dissolved more rapidly (8 minutes vs. 15 - 30 minutes) than lozenges used in studies showing a benefit, allowing for less overall time during which the mouth and throat were exposed to zinc (Hemila, BMJ Open 2020).
In children, zinc syrup taken by mouth and swallowed may modestly help prevent and/or treat common colds (including reductions in school absences and prescriptions for antibiotics). (For more information about ingredients used to treat or prevent colds see ConsumerTips below and Product Reviews of Echinacea, Vitamin C, and Ginseng and the article "Cold and Flus").
Zinc supplementation in high doses (69.6 mg daily) alone or at either a high or low dose (21.8 mg per day) along with anti-oxidants (beta-carotene, vitamin C, and vitamin E) slows the progression of advanced age-related macular degeneration (AMD). The combination (but not zinc alone) also reduces the risk of losing visual acuity in AMD. This was demonstrated in the large Age-Related Eye Disease Study (AREDS) and subsequent AREDS2 (Age-Related Eye Disease Study 2) . However, the AREDS formula failed to prevent the progression of early stage of AMD as well as the progression of cataracts.
Zinc is involved in the regulation of sleep through its role in nerve transmission in the brain, and higher levels of zinc in the blood have been associated with better amounts of sleep in studies of infants, pre-adolescents, and adults — although this does not establish a cause-and-effect relationship. Several sleep studies in people involving zinc-containing formulas that include other ingredients (such as melatonin and other minerals) have shown promise in fostering sleep, but there have been no studies with zinc alone. Increasing the amount of zinc in the blood from a supplement does not necessarily increase levels of zinc in the brain — due to low permeability of the blood-brain barrier for zinc. The most compelling human evidence so far for zinc is a 3-month study in Japan that found that ingesting 50 grams of Pacific oyster (providing 15 mg of zinc) daily, reduced by 5 minutes the time to fall asleep and increased the time in non-REM sleep (a measure of sleep efficiency) (Cherasse, Int J Molec Sci 2017). More research is needed to determine if taking zinc aids sleep and, if it does, the proper dosing.
See Consumer Tips for considerations when buying these zinc-containing vision supplements.
For additional information about supplements to treat or prevent macular degeneration vision see the Encyclopedia article and ConsumerLab.com's Product Review of Lutein and Zeaxanthin Supplements.
Zinc is essential for the production of sperm. Several small studies in countries such as the Netherlands and Iran suggested that supplementation with zinc and folic acid (also important for sperm production) might improve sperm count or quality in healthy men and in those with fertility issues, even if they are not deficient in these nutrients (Wong, Fertil Steril 2002; Azizollahi, J Assist Reprod Genet 2013). However, a large study in the U.S. of over 2,000 men seeking infertility treatment with their partners (about 80% of whom had a diagnosis of male infertility) found that a combination of elemental zinc (30 mg) and high-dose folic acid (5 mg) taken daily for six months did not significantly increase sperm count or improve semen quality or couples' live birth rates compared to placebo, although it was not noted if the men were deficient in either nutrient prior to the study (Schisterman, JAMA 2019).
Zinc may be helpful in Wilson's disease, a disorder where too much copper builds in the body's tissues, as zinc reduces copper levels. Other ways in which high-dose zinc may help, include enhancing the effectiveness of antidepressants and improving symptoms of acne, anorexia nervosa, sickle cell anemia, altered taste sensation (of various origins), and attention deficit-hyperactivity disorder (ADHD). Be aware that high doses of zinc can have adverse effects. (See ConsumerTips for dosage and safety issues regarding zinc supplements).
The balance of current evidence fails to support the use of zinc for cataracts, rheumatoid arthritis or eczema. The use of zinc in high or low doses for benign prostatic hyperplasia (BPH), peptic ulcers, diabetes, osteoporosis, Crohn's disease, tinnitus (ringing in the ear), mouth and skin irritation during radiation therapy for head and neck cancer, and many other conditions for which it is often recommended remains highly speculative.
Quality Concerns and What CL Tested for:
No government agency routinely tests zinc or other dietary supplements for their contents or quality. ConsumerLab.com purchased and evaluated zinc supplements sold in the U.S. and Canada to determine whether they contained the amounts of zinc stated on their labels. Products that listed whole herbs or more than 250 mg of minerals per daily serving also were tested for arsenic, cadmium, and lead -- potential contaminants. All non-chewable tablets and caplets were also tested to be sure that they would properly disintegrate to enable their absorption. (See How Products Were Evaluated for information on testing methods and passing score.)