Effect of zinc supplementation on serum leptin levels and insulin resistance of obese women. Zinc supplementation reduces the incidence of persistent diarrhea and dysentery among low socioeconomic children in India. Zinc supplementation reduces the incidence of acute lower respiratory infections in infants and preschool children: a double-blind, controlled trial. Safety and efficacy of zinc supplementation for children with HIV-1 infection in South Africa: a randomised double-blind placebo-controlled trial. Effect of weekly zinc supplements on incidence of pneumonia and diarrhoea in children younger than 2 years in an urban, low-income population in Bangladesh: randomised controlled trial. Impact of zinc supplementation on persistent diarrhoea in malnourished Bangladeshi children. Simultaneous zinc and vitamin A supplementation in Bangladeshi children: randomised double blind controlled trial. Zinc supplementation in Brazilian children with acute diarrhoea. Zinc supplementation in children with acute diarrhoea.
Leptin is thought to be a lipostatic signal that contributes to body weight regulation. Zinc might play an important role in appetite regulation and its administration stimulates leptin production. However, there are few reports in the literature on its role on leptin levels in the obese population. The present work assesses the effect of zinc supplementation on serum leptin levels in insulin resistance (IR). A prospective double-blind, randomized, clinical, placebo-controlled study was conducted. Fifty-six normal glucose-tolerant obese women (age: 25-45 yr, body mass index [BMI] = 36.2 +/- 2.3 kg/m2) were randomized for treatment with 30 mg zinc daily for 4 wk. Baseline values of both groups were similar for age, BMI, caloric intake, insulin concentration, insulin resistance, and zinc concentration in diet, plasma, urine, and erythrocytes. Insulin and leptin were measured by radioimmunoassay and IR was estimated by the homeostasis model assessment (HOMA). The determinations of zinc in plasma, erythrocytes, and 24- h urine were performed by using atomic absorption spectrophotometry. After 4 wk, BMI, fasting glucose, and zinc concentration in plasma and erythrocyte did not change in either group, although zinc concentration in the urine increased from 385.9 +/- 259.3 to 470.2 +/- 241.2 +/- microg/24 h in the group with zinc supplementation (p < 0.05). Insulin did not change in the placebo group, whereas there was a significant decrease of this hormone in the supplemented group. HOMA also decreased from 5.8 +/- 2.6 to 4.3 +/- 1.7 (p < 0.05) in the zinc-supplemented group but did not change in the placebo group. Leptin did not change in the placebo group. In the zinc group, leptin was 23.6 +/- 12.3 microg/L and did not change. More human data from a unique population of obese individuals with documented insulin resistance would be useful in guiding future studies on zinc supplementation (with higher doses or longer intervals) or different measures. Persistent diarrhea (PD) and dysentery (DD) account for most diarrhea-associated deaths among children in developing countries. Zinc deficiency can cause stunting and impaired immune function, both of which are risk factors for these diarrheal illnesses. We investigated the effect of zinc supplementation on the incidence of PD and DD in a community-based, double-blind randomized trial in children 6-35 mo of age. Increase over baseline in plasma zinc concentrations in the supplemented group compared with a control group (3.61 vs. 0.009 mumol.L-1), indicated successful supplementation. The overall reductions in the zinc supplemented group of 21% in the incidence of PD (95% CI -6 to 42%) and 14% in the incidence of dysentery (95% CI -15 to 36%) were not significant. There was a significant interaction of treatment effect with baseline plasma zinc concentration and age for PD and with gender for DD. In the zinc-supplemented group compared with the control group, the incidence of PD was reduced by 73% (P < 0.05; 95% CI 34 to 91%) in children with a baseline zinc < 7.65 mumol.L-1 and by 49% (P < 0.05; 95%CI 24 to 66%) in children > 11 mo of age. Zinc supplementation resulted in a 38% (P < 0.05 95%CI 8 to 59%) reduction in the incidence of DD in boys. There was no effect on PD among children 6-11 mo old or on DD in girls. In conclusion, zinc supplementation had a significant impact on the incidence of persistent diarrhea in children > 1 y old and in children with low plasma zinc, as well as on dysentery in boys. These findings may have important implications for reducing diarrhea-related morbidity and mortality. Increased acute lower respiratory infection incidence, severity, and mortality are associated with malnutrition, and reduced immunological competence may be a mechanism for this association. Because zinc deficiency results in impaired immunocompetence and zinc supplementation improves immune status, we hypothesized that zinc deficiency is associated with increased incidence and severity of acute lower respiratory infection.
                We evaluated the effect of daily supplementation with 10 mg of elemental zinc on the incidence and prevalence of acute lower respiratory infection in a double-blind, randomized, controlled trial in 609 children (zinc, n = 298; control, n = 311) 6 to 35 months of age. Supplementation and morbidity surveillance were done for 6 months.
                After 120 days of supplementation, the percentage of children with plasma zinc concentrations <60 microg/dL decreased from 35.6% to 11.6% in the zinc group, whereas in the control group it increased from 36.8% to 43.6%. Zinc-supplemented children had 0.19 acute lower respiratory infection episodes/child/year compared with 0.35 episodes/child/year in the control children. After correction for correlation of data using generalized estimating equation regression methods, there was a reduction of 45% (95% confidence interval, 10% to 67%) in the incidence of acute lower respiratory infections in zinc-supplemented children.
                A dietary zinc supplement resulted in a significant reduction in respiratory morbidity in preschool children. These findings suggest that interventions to improve zinc intake will improve the health and survival of children in developing countries. Zinc deficiency is associated with impaired immune function and an increased risk of infection. Supplementation can decrease the incidence of diarrhoea and pneumonia in children in resource-poor countries. However, in children with HIV-1 infection, the safety of zinc supplementation is uncertain. We aimed to assess the role of zinc in HIV-1 replication before mass zinc supplementation is recommended in regions of high HIV-1 prevalence.
                We did a randomised double-blind placebo-controlled equivalence trial of zinc supplementation at Grey's Hospital in Pietermaritzburg, South Africa. 96 children with HIV-1 infection were randomly assigned to receive 10 mg of elemental zinc as sulphate or placebo daily for 6 months. Baseline measurements of plasma HIV-1 viral load and the percentage of CD4+ T lymphocytes were established at two study visits before randomisation, and measurements were repeated 3, 6, and 9 months after the start of supplementation. The primary outcome measure was plasma HIV-1 viral load. Analysis was per protocol.
                The mean log(10) HIV-1 viral load was 5.4 (SD 0.61) for the placebo group and 5.4 (SD 0.66) for the zinc-supplemented group 6 months after supplementation began (difference 0.0002, 95% CI -0.27 to 0.27). 3 months after supplementation ended, the corresponding values were 5.5 (SD 0.77) and 5.4 (SD 0.61), a difference of 0.05 (-0.24 to 0.35). The mean percentage of CD4+ T lymphocytes and median haemoglobin concentrations were also similar between the two groups after zinc supplementation. Two deaths occurred in the zinc supplementation group and seven in the placebo group (p=0.1). Children given zinc supplementation were less likely to get watery diarrhoea than those given placebo. Watery diarrhoea was diagnosed at 30 (7.4%) of 407 clinic visits in the zinc-supplemented group versus 65 (14.5%) of 447 visits in the placebo group (p=0.001).
                Zinc supplementation of HIV-1-infected children does not result in an increase in plasma HIV-1 viral load and could reduce morbidity caused by diarrhoea.
                Programmes to enhance zinc intake in deficient populations with a high prevalence of HIV-1 infection can be implemented without concern for adverse effects on HIV-1 replication. In view of the reductions in diarrhoea and pneumonia morbidity, zinc supplementation should be used as adjunct therapy for children with HIV-1 infection. Pneumonia and diarrhoea cause much morbidity and mortality in children younger than 5 years. Most deaths occur during infancy and in developing countries. Daily regimens of zinc have been reported to prevent acute lower respiratory tract infection and diarrhoea, and to reduce child mortality. We aimed to examine whether giving zinc weekly could prevent clinical pneumonia and diarrhoea in children younger than 2 years.
                1665 poor, urban children aged 60 days to 12 months were randomly assigned zinc (70 mg) or placebo orally once weekly for 12 months. Children were assessed every week by field research assistants. Our primary outcomes were the rate of pneumonia and diarrhoea. The rates of other respiratory tract infections were the secondary outcomes. Growth, final serum copper, and final haemoglobin were also measured. Analysis was by intention to treat.
                34 children were excluded before random assignment to treatment group because they had tuberculosis. 809 children were assigned zinc, and 812 placebo. After treatment assignment, 103 children in the treatment group and 44 in the control group withdrew. There were significantly fewer incidents of pneumonia in the zinc group than the control group (199 vs 286; relative risk 0.83, 95% CI 0.73-0.95), and a small but significant effect on incidence of diarrhoea (1881 cases vs 2407; 0.94, 0.88-0.99). There were two deaths in the zinc group and 14 in the placebo group (p=0.013). There were no pneumonia-related deaths in the zinc group, but ten in the placebo group (p=0.013). The zinc group had a small gain in height, but not weight at 10 months compared with the placebo group. Serum copper and haemoglobin concentrations were not adversely affected after 10 months of zinc supplementation.
                70 mg of zinc weekly reduces pneumonia and mortality in young children. However, compliance with weekly intake might be problematic outside a research programme. To evaluate the impact of zinc supplementation on the clinical recovery and body weight of children with persistent diarrhoea, a randomized, double-blind, controlled trial was conducted in 190 children with persistent diarrhoea aged between 3 and 24 months. Children were randomly allocated to receive either zinc (20 mg d(-1)) syrup with multivitamin (2 x RDA) or multivitamin alone in three divided daily doses for 2 weeks. The trial was conducted in a diarrhoeal disease hospital in Dhaka, Bangladesh. Duration until clinical recovery (d), impact on body weight and serum zinc level after 2 weeks of zinc supplementation were recorded. The duration of illness was significantly reduced (33%) with zinc supplementation among children who were underweight (< or =70% wt/age, p = 0.03). Supplemented male children also had a significant reduction (27%) in duration for recovery compared with unsupplemented children (p = 0.05). From baseline to convalescence, zinc-supplemented children maintained their serum zinc concentration (13.4 vs 13.6 micromol l(-1)), whereas unsupplemented children had a decrease in serum zinc after the 2 weeks of diarrhoea (13.6 vs 11.8 micromol l(-1),p < 0.03). The mean body weight of the children in the supplemented group was maintained (5.72 vs 5.70 kg, p = 0.62) during hospitalization, unlike that of the control group, in which there was a reduction in body weight (5.75 vs 5.67 kg, p = 0.05). Five children in the unsupplemented group and one child in the zinc-supplemented group died during the 2 weeks of supplementation (p = 0.06). Zinc supplementation in persistent diarrhoea significantly reduced the length of the recovery period in malnourished children and prevented a fall in body weight and serum zinc concentration, indicating that zinc is a beneficial therapeutic strategy in this high-risk childhood illness. To evaluate the effect of simultaneous zinc and vitamin A supplementation on diarrhoea and acute lower respiratory infections in children.
                Randomised double blind placebo controlled trial.
                Urban slums of Dhaka, Bangladesh.
                800 children aged 12-35 months were randomly assigned to one of four intervention groups: 20 mg zinc once daily for 14 days; 200 000 IU vitamin A, single dose on day 14; both zinc and vitamin A; placebo. The children were followed up once a week for six months, and morbidity information was collected.
                The incidence and prevalence of diarrhoea were lower in the zinc and vitamin A groups than in the placebo group. Zinc and vitamin A interaction had a rate ratio (95% confidence interval) of 0.79 (0.66 to 0.94) for the prevalence of persistent diarrhoea and 0.80 (0.67 to 0.95) for dysentery. Incidence (1.62; 1.16 to 2.25) and prevalence (2.07; 1.76 to 2.44) of acute lower respiratory infection were significantly higher in the zinc group than in the placebo group. The interaction term had rate ratios of 0.75 (0.46 to 1.20) for incidence and 0.58 (0.46 to 0.73) for prevalence of acute lower respiratory infection.
                Combined zinc and vitamin A synergistically reduced the prevalence of persistent diarrhoea and dysentery. Zinc was associated with a significant increase in acute lower respiratory infection, but this adverse effect was reduced by the interaction between zinc and vitamin A. Although oral rehydration therapy greatly reduces mortality from diarrhoeal diseases, it has little effect on stool frequency. However, there is mounting evidence that zinc is an effective adjunct to the treatment of diarrhoea, although few studies have examined its efficacy in Latin America. This study assessed the efficacy of zinc supplementation in children with acute diarrhoea in Brazil. The study was a double-blind, placebo-controlled, randomised, clinical trial in children <5 years of age attending emergency services in Sergipe, Brazil. Subjects received zinc or vitamin C as placebo. There was a marked reduction in the duration of the diarrhoea (1.1 vs 2.6 days) and of watery stools in the zinc-supplemented group. The efficacy of zinc was independent of the presence of viral enteropathogens in the stools. It is concluded that, similar to studies in India and Bangladesh, zinc could be an important adjunct for treating acute diarrhoea in Brazilian children. In Nigeria, diarrhoeal disease is second only to malaria as a cause of death the under 5 age group. This study was aimed at assessing the benefit or otherwise of zinc supplement in acute diarrhoea.
                This was a multi-centred randomized double blind controlled study. Children with acute diarrhoea aged between 6 and 24 months were randomized into zinc supplemented and placebo groups. Plasma zinc levels were analyzed at enrollment and at the end of the study. The children were reviewed for the next three months from the time of enrollment.
                The mean plasma zinc levels at baseline and at the end of the study were 0.06 +/- 0.04 and 0.067 +/- 0.03 ppm in the zinc supplemented group and 0.11 +/- 0.02 and 0.05 +/- 0.03 ppm in the control group. The differences were not statistically significant. The zinc supplemented group had an average weight gain of 1.1 kg as against 0.73 kg (p = 0.00) for the control group in the study period. No adverse effect was reported on account of zinc supplementation.
                Zinc supplementation is beneficial in acute diarrhoea as observed in this study.
There is currently no evidence to suggest the use of zinc supplementation in the prevention of type 2 diabetes mellitus. Future trials will have to standardise outcomes measures such as incidence of type 2 diabetes mellitus, decrease of the insulin resistance, quality of life, diabetic complications, all-cause mortality and costs.