special subjects
Zinc Supplements
Evidence
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 ( References ). 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 ( 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 ( References ). 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 ( 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 ( References ). 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% ( References ). However, the hemoglobin A1C reduction with zinc monosupplement treatment was only 0.35%. 