Wellness Database: Zinc
Zinc improves memory, reduces cancer risks, and may prevent atherosclerosis.
Zinc May Reduce Depression
Summary: In this review, the authors examined results from all published, randomized, controlled trials investigating the efficacy of zinc supplementation in reducing or preventing depressive symptoms, and after reviewing results from 4 studies that met their inclusion criteria, the authors found that as an adjunct to anti-depressant drug treatment, zinc supplementation was found to significantly reduce depressive symptom scores. Less clear, but evidence also points to the benefits of zinc as a stand-alone intervention. The authors state, "However, there are methodological limitations in existing studies and so further well-designed, adequately powered research is required."
Reference: "The efficacy of zinc supplementation in depression: Systematic review of randomised controlled trials," Lai J, Moxey A, et al, J Affect Disord, 2011 July 26; [Epub ahead of print]. (Address: Centre of Clinical Epidemiology and Biostatistics, School of Medicine and Public Health, University of Newcastle, New South Wales, Australia).
High Doses of Zinc May Decrease Cold Duration
Summary: In this systematic review, the authors analyzed results from 13 placebo-controlled trials examining the effects of zinc lozenges on the duration of the common cold, and they found a 42% reduction in the duration of the common cold associated with use of zinc acetate in daily doses over 75 mg, and a 20% reduction in the duration of colds associated with zinc salts other than acetate in daily doses over 75 mg. In the 5 trials where less than 75 mg zinc was used, no beneficial effect was found. The authors state, "This study shows strong evidence that the zinc lozenge effect on common cold duration is heterogeneous so that benefit is observed with high doses of zinc but not with low doses."
Reference: "Zinc lozenges may shorten the duration of colds: a systematic review," Hemila H, Open Respir Med J, 2011; 5: 51-8. Epub ahead of print. (Address: Department of Public Health, University of Helsinki, Helsinki, Finland).
Supplementation for a Metabolic Tune Up
An optimum intake of micronutrients and metabolites, which varies with age and genetic constitution, would tune up metabolism and give a marked increase in health, particularly for the poor, young, obese, and elderly, at little cost. (1) DNA damage. Deficiency of vitamins B-12, folic acid, B-6, C or E, or iron or zinc appears to mimic radiation in damaging DNA by causing single- and double-strand breaks, oxidative lesions or both. Half of the population may be deficient in at least one of these micronutrients. (2) The Km concept. Approximately 50 different human genetic diseases that are due to a poorer binding affinity (Km) of the mutant enzyme for its coenzyme can be remedied by feeding high-dose B vitamins, which raise levels of the corresponding coenzyme. Many polymorphisms also result in a lowered affinity of enzyme for coenzyme. (3) Mitochondrial oxidative decay. This decay, which is a major contributor to aging, can be ameliorated by feeding old rats the normal mitochondrial metabolites acetyl carnitine and lipoic acid at high levels. Many common micronutrient deficiencies, such as iron or biotin, cause mitochondrial decay with oxidant leakage leading to accelerated aging and neural decay.
Arch Biochem Biophys. 2004 Mar 1;423(1):227-34.
Zinc Reduces Cold Duration and Symptoms
Background: Adults and children in the United States get two to six colds per year. Evidence that zinc is effective therapy for colds is inconsistent.
Objective: To test the efficacy of zinc acetate lozenges in reducing the duration of symptoms of the common cold.
Design: Randomized, double-blind, placebo-controlled trial.
Setting: Detroit Medical Center, Detroit, Michigan.
Patients: 50 ambulatory volunteers recruited within 24 hours of developing symptoms of the common cold.
Intervention: Participants took one lozenge containing 12.8 mg of zinc acetate or placebo every 2 to 3 hours while awake as long as they had cold symptoms.
Measurements: Subjective symptom scores for sore throat, nasal discharge, nasal congestion, sneezing, cough, scratchy throat, hoarseness, muscle ache, fever, and headache were recorded daily for 12 days. Plasma zinc and proinflammatory cytokine levels were measured on day 1 and after participants were well.
Results: Forty-eight participants completed the study (25 in the zinc group and 23 in the placebo group). Compared with the placebo group, the zinc group had shorter mean overall duration of cold symptoms (4.5 vs. 8.1 days), cough (3.1 [95% CI, 2.1 to 4.1] vs. 6.3 [CI, 4.9 to 7.7] days), and nasal discharge (4.1 [CI, 3.3 to 4.9] vs. 5.8 [CI, 4.3 to 7.3] days) and decreased total severity scores for all symptoms (P < 0.002, test for treatment × time interaction). Mean changes in soluble interleukin-1 receptor antagonist level differed nonsignificantly between the zinc group and the placebo group (difference between changes, −89.4 pg/mL [CI, −243.6 to −64.8 pg/mL]).
Conclusion: Administration of zinc lozenges was associated with reduced duration and severity of cold symptoms, especially cough. Improvement in clinical symptoms with zinc treatment may be related to a decrease in proinflammatory cytokine levels; however, in this study, the observed differences between changes in cytokine levels in zinc and placebo recipients were not significant.
Zinc Acetate Lozenges To Treat the Common Cold. Ann Intern Med August 15, 2000 133:245
Zinc Increase Prostate Cancer Survival
In a population-based cohort study involving 525 men under 80 years of age diagnosed with prostate cancer, out of which 42% died of prostate cancer and 49% died of other causes, high dietary intake of zinc was found to be associated with a reduced risk of prostate cancer-specific mortality (HR=0.64), with a stronger association found in men with localized tumors (HR=0.24). No association was found between zinc intake and mortality from other causes. The authors conclude that, "... high dietary intake of zinc is associated with lower prostate cancer-specific mortality after diagnosis, particularly in men with localized disease."
Zinc Supplementation Associated With Weight Loss
Zinc is an often overlooked nutrient. This research demonstrates its importance in weight loss in children.
In a triple-masked, randomized, placebo-controlled, crossover trial involving 60 obese Iranian children, supplementation with zinc (20 mg elemental zinc) for a period of 8 weeks was found to be associated with reductions in ApoB/ApoA-I ratio, ox-LDL, leptin, malondialdehyde, total cholesterol, LDL cholesterol, hs-CRP, and markers of insulin resistance. In addition, supplementation with zinc was associated with decreases in mean weight, BMI, and BMI Z-score, while these values increased when given placebo. The authors conclude, "These results are particularly important in light of the deleterious consequences of childhood obesity and early changes in markers of inflammatory and oxidative stress. We suggest exploring the direct clinical application of zinc supplementation in childhood obesity in future studies."
Read the study here: http://www.ncbi.nlm.nih.gov/pubmed/21028969
Iron and Zinc Supplements Improve Memory in Children
Iron and zinc deficiency is surprisingly common among children. This study demonstrates the benefits of supplementation.
In a study involving 100 children aged 6 to 11 years, results indicate that iron and zinc deficiency may be associated with memory deficits which may improve with iron and zinc supplementation. The children were categorized as iron deficient, zinc deficient and iron and zinc deficient. Children in the deficient group received supplementation with iron (2 mg/kg body weight/day) and zinc (5 mg/day). Children aged 6-8 years and 9-11 years with iron and zinc deficiency showed memory deficits (verbal and non-verbal memory in the 9-11 age group, and only non-verbal memory in the 6-8 age group), which improved with iron and zinc supplementation. Thus, the authors of this study conclude, "Iron and zinc deficiency is associated with memory deficits in children. There is a marked improvement in memory after supplementation."
Read more here: http://www.ncbi.nlm.nih.gov/pubmed/20972302
Zinc Supplementation May Help Protect Against Atherosclerosis
In a randomized, double-blind, placebo-controlled study involving 40 healthy elderly subjects (aged 56-83 years old), results indicate that zinc supplementation may exert atheroprotective effects. The subjects were randomized to 45 mg zinc daily or placebo for a period of 6 months. At intervention end, zinc supplemented subjects showed decreased concentrations of plasma high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, macrophage chemoattractant protein 1 (MCP-1), vascular cell adhesion molecule 1 (VCAM-1), secretory phospholipase A2, and malondialdehyde and hydroxyalkenals (MDA+HAE). Additionally, cell culture studies showed that zinc supplementation decreased the generation of tumor necrosis factor-alpha, IL-1beta, VCAM-1, and MDA+HAE and the activation of nuclear transcription factor kappaB and increased antiinflammatory proteins A20 and peroxisome proliferator-activated receptor-alpha in human monocytic leukemia THP-1 cells and human aortic endothelial cells. Thus, the authors of this study conclude, "These findings suggest that zinc may have a protective effect in atherosclerosis because of its antiinflammatory and antioxidant functions."
"Zinc decreases C-reactive protein, lipid peroxidation, and inflammatory cytokines in elderly subjects: a potential implication of zinc as an atheroprotective agent," Bao B, Cardozo LJ, et al, Am J Clin Nutr, 2010 Apr 28.
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Nutrients and Diet
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