Zinc Research
52 peer-reviewed studies · Evidence score: 9/10
Effects of Daily Zinc Alone or in Combination with Other Nutrient Supplements on the Risk of Malaria Parasitaemia: A Systematic Review and Meta-Analysis of Randomised Controlled Trials
Kotepui M et al. • Nutrients (2023)
Further research with larger sample sizes is warranted to explore the potential effects of multi-nutrient supplementation and to identify more specific micronutrients and additional factors associated with the risk of malaria, rather than just zinc alone, among individuals in different malaria-endemic areas.
- The effect sizes, represented as risk ratios (RRs) with 95% confidence intervals (CIs), were standardised by transforming them into log RRs and then pooling them using a fixed-effects or random-effects model depending on the heterogeneity across studies.
- The meta-analysis revealed that zinc supplementation alone did not significantly affect the risk of malaria parasitaemia compared with placebo (p = 0.30, log RR = 0.05, 95% CI: -0.05-0.15, I2 = 0.00%, with 566 malaria cases in the zinc intake group and 521 malaria cases in the placebo group).
- The findings of this systematic review indicate that zinc supplementation, either alone or combined with the supplementation of other micronutrients such as vitamin A, iron, or multiple nutrients, does not significantly alter the risk of malaria parasitaemia.
The Effect of Zinc Supplementation on Lipid Profiles in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Dose-Response Meta-Analysis of Randomized Clinical Trials
Heidari Seyedmahalleh M et al. • Advances in nutrition (Bethesda, Md.) (2023)
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- Significant improvement was observed in all 4 lipid profile components.
- Following zinc supplementation, a significant decrease was observed in TC (weighted mean difference [WMD]: -16.16; 95% confidence interval [CI]: -26.43, -5.89; P = 0.002), LDL (WMD: -6.18; 95% CI: -9.35, -3.02; P < 0.001), and TG (WMD: -13.08; 95% CI: -21.83, -4.34; P = 0.003).
- After analyzing 13 studies reporting HDL, a significant increase was seen (WMD: 3.76; 95% CI: 1.30, 6.22; P = 0.003).
Efficacy of Zinc Supplementation in the Management of Primary Dysmenorrhea: A Systematic Review and Meta-Analysis
Hsu TJ et al. • Nutrients (2024)
Zinc supplementation is an effective and well-tolerated option for reducing pain severity in women with primary dysmenorrhea.
- Zinc supplementation significantly reduced pain severity compared to placebo (Hedges's g = -1.541; 95% CI: -2.268 to -0.814; p < 0.001), representing a clinically meaningful reduction in pain.
- Meta-regression indicated that longer treatment durations (≥8 weeks) were associated with greater pain reduction (p = 0.003).
- While higher zinc doses provided additional pain relief, the incremental benefit per additional milligram was modest (regression coefficient = -0.02 per mg; p = 0.005).
Zinc supplementation and immune factors in adults: a systematic review and meta-analysis of randomized clinical trials
Jafari A et al. • Critical reviews in food science and nutrition (2022)
Zinc supplementation decreased the CRP, hs-CRP and TNF-α, IL-6, neutrophil and increased CD3 and CD4 level significantly.
- CD4 level also increased significantly, (WMD: 1.79; 95% CI: 0.57 to 3, p = 0.004).
- Zinc supplementation decreased the CRP, hs-CRP and TNF-α, IL-6, neutrophil and increased CD3 and CD4 level significantly.
- Further research warranted to confirm findings
Zinc supplementation for improving pregnancy and infant outcome
Carducci B et al. • The Cochrane database of systematic reviews (2021)
There is not enough evidence that zinc supplementation during pregnancy results in improvements in maternal or neonatal outcomes.
- The evidence suggests that zinc supplementation may result in little or no difference in reducing preterm births (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.74 to 1.03; 21 studies, 9851 participants; low-certainty evidence).
- Further, zinc supplementation may make little or no difference in reducing the risk of stillbirth (RR 1.22, 95% CI 0.80 to 1.88; 7 studies, 3295 participants; low-certainty evidence), or perinatal deaths (RR 1.10, 95% CI 0.81 to 1.51; 2 studies, 2489 participants; low-certainty evidence).
- There is not enough evidence that zinc supplementation during pregnancy results in improvements in maternal or neonatal outcomes.
Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trials
Hunter J et al. • BMJ open (2021)
In adult populations unlikely to be zinc deficient, there was some evidence suggesting zinc might prevent RTIs symptoms and shorten duration.
- Compared with placebo, oral or intranasal zinc prevented 5 RTIs per 100 person-months (95% CI 1 to 8, numbers needed to treat (NNT)=20, moderate-certainty/quality).
- Sublingual zinc did not prevent clinical colds following human rhinovirus inoculations (relative risk, RR 0.96, 95% CI 0.77 to 1.21, moderate-certainty/quality).
- On average, symptoms resolved 2 days earlier with sublingual or intranasal zinc compared with placebo (95% CI 0.61 to 3.50, very low-certainty/quality) and 19 more adults per 100 were likely to remain symptomatic on day 7 without zinc (95% CI 2 to 38, NNT=5, low-certainty/quality).
Zinc sulfate on neonatal hyperbilirubinemia: an updated systematic review and meta-analysis
de Oliveira HM et al. • European journal of pediatrics (2024)
The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
- A total of 690 (51.1%) neonates received zinc sulfate.
- The Impact of Zinc Sulfate on the Treatment of Neonatal Hyperbilirubinemia: An Updated Systematic Review and Meta-Analysis"; CRD42024586259; Link: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=586259.© 2024.
- The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Effect of zinc supplementation on mortality in under 5-year children: a systematic review and meta-analysis of randomized clinical trials
Rouhani P et al. • European journal of nutrition (2022)
This meta-analysis on RCTs revealed that zinc supplementation in under 5-year children has significantly reduced the risk of all-cause mortality.
- Combining 30 RRs from 28 RCTs including 237,068 participants revealed that zinc supplementation has significantly reduced the risk of all-causes mortality by 16% in children (SRR: 0.84, 95% CI: 0.74, 0.96).
- A follow-up duration of less than 1 year after supplementation resulted in 54% reduced risk of mortality (0.46; 0.33, 0.63) with no heterogeneity between investigations.
- Subgroup analysis by zinc dosage showed that assigning ≥ 10 mg/d zinc to under five children and duration of less than 11 months of intervention decreased the risk of all-cause mortality by 44% (0.56; 0.42, 0.75) and 48% (0.52; 0.38, 0.72), respectively.
Vitamin and Mineral Supplementation During Pregnancy on Maternal, Birth, Child Health and Development Outcomes in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis
Oh C et al. • Nutrients (2020)
In addition, they further contribute to the ongoing discourse of choosing antenatal MMN over IFA as the standard of care in LMICs.
- IFA supplementation showed notable improvement in maternal anemia and the reduction in low birthweight, whereas LNS supplementation had no apparent effect on outcomes; further research that compares LNS and MMN supplementation could help understand differences with these commodities.
- For single micronutrient supplementation, improvements were noted in only a few outcomes, mainly pre-eclampsia/eclampsia (calcium), maternal anemia (iron), preterm births (vitamin D), and maternal serum zinc concentration (zinc).
- These findings highlight that micronutrient-specific supplementation should be tailored to specific groups or needs for maximum benefit.
Prevalence of Zinc Deficiency in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis
Zupo R et al. • Nutrients (2022)
Clinicians in the field are advised to list zinc among trace elements to be monitored in serum.
- Pooled analyses by the IBD subgroup showed a total population of 1677 with CD, for an overall mean zinc deficiency prevalence of 54% and 95% confidence intervals (CI) ranging from 0.51 to 0.56, versus 41% (95%CI 0.38-0.45) in the UC population (n = 806).
- The overall prevalence at meta-analysis was estimated at 50% (95%CI 0.48-0.52), but with high heterogeneity, I2 = 96%.
- The risk of bias across selected studies was moderate to low.
Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trials
Wang X et al. • The American journal of clinical nutrition (2019)
Our analysis revealed that several key glycemic indicators are significantly reduced by zinc supplementation, particularly the FG in subjects with diabetes and in subjects who received an inorganic zinc supplement.
- Our analysis revealed that several key glycemic indicators are significantly reduced by zinc supplementation, particularly the FG in subjects with diabetes and in subjects who received an inorganic zinc supplement.
- Together, these findings support the notion that zinc supplementation may have clinical potential as an adjunct therapy for preventing or managing diabetes.
- This trial was registered at PROSPERO as CRD42018111838.
Zinc supplements for preventing otitis media
Gulani A et al. • The Cochrane database of systematic reviews (2014)
Evidence on whether zinc supplementation can reduce the incidence of otitis media in healthy children under the age of five years living in low- and middle-income countries is mixed.
- A small trial of 39 infants undergoing treatment for severe malnutrition suggested a benefit of zinc for the mean number of episodes of otitis media (mean difference (MD) -1.12 episodes, 95% CI -2.21 to -0.03).
- Evidence on whether zinc supplementation can reduce the incidence of otitis media in healthy children under the age of five years living in low- and middle-income countries is mixed.
- There is some evidence of benefit in children being treated for marasmus (severe malnutrition), but this is based on one small trial and should therefore be treated with caution.
Effects of Zinc Supplementation on Cardiometabolic Risk Factors: a Systematic Review and Meta-analysis of Randomized Controlled Trials
Khazdouz M et al. • Biological trace element research (2020)
Thus, it appeared that zinc supplementation might be associated with a decrease in cardiometabolic risk factors contributing to a reduction in risk of atherosclerosis.
- Random- or fixed-effects meta-analysis method was used to estimate the standardized mean difference (SMD) and 95% confidence interval (CI).
- Meta-analysis showed that zinc supplementation significantly decreased plasma levels of triglyceride (SMD - 0.66, 95% CI - 1.27, - 0.06), very-low-density lipoprotein (SMD - 1.59, 95% CI - 2.86, - 0.31), and total cholesterol (SMD - 0.65, 95% CI - 1.15, - 0.15).
- Similarly, zinc supplementation significantly decreased fasting blood glucose (SMD - 0.52, 95% CI - 0.96, - 0.07) and HbA1c (SMD - 0.64, 95% CI - 1.27, - 0.02).
Zinc Supplementation and Body Weight: A Systematic Review and Dose-Response Meta-analysis of Randomized Controlled Trials
Abdollahi S et al. • Advances in nutrition (Bethesda, Md.) (2020)
Although more high-quality studies are needed to reach a definitive conclusion, our study supports the view that zinc may be associated with body weight.Copyright © American Society for Nutrition 2019.
- Dose-response analyses revealed a significant nonlinear effect of supplementation dosage on BMI (P = 0.001).
- Although more high-quality studies are needed to reach a definitive conclusion, our study supports the view that zinc may be associated with body weight.Copyright © American Society for Nutrition 2019.
- Further research warranted to confirm findings
Zinc for the common cold
Singh M, Das RR • Cochrane Database of Systematic Reviews (2013)
Zinc administered within 24 hours of onset of symptoms reduces the duration of common cold symptoms.
- Reduces cold duration by ~1 day
- Most effective when taken early
- Lozenges may be most effective form
Zinc, copper, and selenium levels in vitiligo: a systematic review and meta-analysis
Anam K et al. • Scientific reports (2024)
This meta-analysis examined the effects of Copper.
- Publication bias was not found for the studies analysed.
- This study analyses the association of serum micronutrient levels and vitiligo among patients and controls from published research along with sub-group analysis specific to Asian populations using a meta-analysis.
- Low serum levels of Zinc and copper and high selenium levels are associated with Vitiligo.© 2024.
Interventions for managing taste disturbances
Kumbargere Nagraj S et al. • The Cochrane database of systematic reviews (2017)
We found very low-quality evidence that was insufficient to conclude on the role of zinc supplements to improve taste acuity reported by patients and very low-quality evidence that zinc supplements improve taste acuity in patients with zinc deficiency/idiopathic taste disorders.
- We assessed three trials (30%) as having a low risk of bias, four trials (40%) at high risk of bias and three trials (30%) as having an unclear risk of bias.
- Out of these nine, two trials assessed the patient-reported outcome for improvement in taste acuity using zinc supplements (risk ratio (RR) 1.40, 95% confidence interval (CI) 0.94 to 2.09; 119 participants, very low-quality evidence).
- We meta-analysed for taste acuity improvement using objective outcome (continuous data) in idiopathic and zinc-deficient taste disorder patients (standardised mean difference (SMD) 0.44, 95% CI 0.23 to 0.65; 366 participants, three trials, very low-quality evidence).
Calcium, zinc, and vitamin D in breast milk: a systematic review and meta-analysis
Rios-Leyvraz M et al. • International breastfeeding journal (2023)
This review provides global estimates of calcium, zinc and vitamin D content in breast milk, as well as indications on changes over time and depending on influencing factors.
- A total of 154 studies reporting on breast milk calcium were identified, with a mean calcium concentration in breast milk of 261 mg/L (95% CI: 238, 284).
- A total of 242 studies reporting on breast milk zinc were identified, with a mean zinc concentration of 2.57 mg/L (95% CI: 2.50, 2.65).
- A total of 43 studies reporting on breast milk vitamin D were identified, with a mean total antirachitic activity of breast milk of 58 IU/L (95% CI: 45, 70), which consisted mostly of 25OHD3, and smaller amounts of vitamin D3, 25OHD2 and vitamin D2.
Zinc supplementation in prediabetes mellitus
Jayawardena R et al. • Minerva endocrinology (2022)
Zinc supplementation demonstrated beneficial effects on glycemic and lipid parameters in individuals with prediabetes.
- Zinc supplementation demonstrated beneficial effects on glycemic and lipid parameters in individuals with prediabetes.
- It may have the potential to reduce the prevalence of prediabetes and control associated morbidity and mortality.
- Further research warranted to confirm findings
Zinc supplementation for acute and persistent watery diarrhoea in children: A systematic review and meta-analysis
Ali AA et al. • Journal of global health (2024)
Zinc should continue to be recommended in children under the age of 10 years with acute or persistent diarrhoea, but moderate certainty of evidence concludes that the dose of zinc should be reduced.
- In children with persistent diarrhoea, zinc supplementation led to a greater proportion of children who recovered from diarrhoea (RR = 1.75; 95% CI = 1.34, 2.30; low certainty of evidence).
- Zinc should continue to be recommended in children under the age of 10 years with acute or persistent diarrhoea, but moderate certainty of evidence concludes that the dose of zinc should be reduced.
- However, further multi-country randomised clinical trials are required with a direct comparison to assess the appropriate dosage, duration and adverse effects.