Serum zinc reference intervals and its relationship with dietary, functional, and biochemical indicators in 6- to 9-year-old healthy children

Zinc level and effect of zinc supplementation on growth in a subset of Sudanese children with sickle cell disease

xxxx

Zinc supplementation for preventing mortality, morbidity, and growth failure in children aged 6 months to 12 years

BACKGROUND

Zinc deficiency is prevalent in low- and middle-income countries, and is considered a significant risk factor for morbidity, mortality, and linear growth failure. The effectiveness of preventive zinc supplementation in reducing prevalence of zinc deficiency needs to be assessed.

OBJECTIVES

To assess the effects of zinc supplementation for preventing mortality and morbidity, and for promoting growth, in children aged 6 months to 12 years.

SEARCH METHODS

A previous version of this review was published in 2014. In this update, we searched CENTRAL, MEDLINE, Embase, five other databases, and one trials register up to February 2022, together with reference checking and contact with study authors to identify additional studies.

SELECTION CRITERIA

Randomized controlled trials (RCTs) of preventive zinc supplementation in children aged 6 months to 12 years compared with no intervention, a placebo, or a waiting list control. We excluded hospitalized children and children with chronic diseases or conditions. We excluded food fortification or intake, sprinkles, and therapeutic interventions.

DATA COLLECTION AND ANALYSIS

Two review authors screened studies, extracted data, and assessed the risk of bias. We contacted study authors for missing information and used GRADE to assess the certainty of evidence. The primary outcomes of this review were all-cause mortality; and cause-specific mortality, due to all-cause diarrhea, lower respiratory tract infection (LRTI, including pneumonia), and malaria. We also collected information on a number of secondary outcomes, such as those related to diarrhea and LRTI morbidity, growth outcomes and serum levels of micronutrients, and adverse events.

MAIN RESULTS

We included 16 new studies in this review, resulting in a total of 96 RCTs with 219,584 eligible participants. The included studies were conducted in 34 countries; 87 of them in low- or middle-income countries. Most of the children included in this review were under five years of age. The intervention was delivered most commonly in the form of syrup as zinc sulfate, and the most common dose was between 10 mg and 15 mg daily. The median duration of follow-up was 26 weeks. We did not consider that the evidence for the key analyses of morbidity and mortality outcomes was affected by risk of bias. High-certainty evidence showed little to no difference in all-cause mortality with preventive zinc supplementation compared to no zinc (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.84 to 1.03; 16 studies, 17 comparisons, 143,474 participants). Moderate-certainty evidence showed that preventive zinc supplementation compared to no zinc likely results in little to no difference in mortality due to all-cause diarrhea (RR 0.95, 95% CI 0.69 to 1.31; 4 studies, 132,321 participants); but probably reduces mortality due to LRTI (RR 0.86, 95% CI 0.64 to 1.15; 3 studies, 132,063 participants) and mortality due to malaria (RR 0.90, 95% CI 0.77 to 1.06; 2 studies, 42,818 participants); however, the confidence intervals around the summary estimates for these outcomes were wide, and we could not rule out a possibility of increased risk of mortality. Preventive zinc supplementation likely reduces the incidence of all-cause diarrhea (RR 0.91, 95% CI 0.90 to 0.93; 39 studies, 19,468 participants; moderate-certainty evidence) but results in little to no difference in morbidity due to LRTI (RR 1.01, 95% CI 0.95 to 1.08; 19 studies, 10,555 participants; high-certainty evidence) compared to no zinc. There was moderate-certainty evidence that preventive zinc supplementation likely leads to a slight increase in height (standardized mean difference (SMD) 0.12, 95% CI 0.09 to 0.14; 74 studies, 20,720 participants). Zinc supplementation was associated with an increase in the number of participants with at least one vomiting episode (RR 1.29, 95% CI 1.14 to 1.46; 5 studies, 35,192 participants; high-certainty evidence). We report a number of other outcomes, including the effect of zinc supplementation on weight and serum markers such as zinc, hemoglobin, iron, copper, etc. We also performed a number of subgroup analyses and there was a consistent finding for a number of outcomes that co-supplementation of zinc with iron decreased the beneficial effect of zinc.

AUTHORS' CONCLUSIONS

Even though we included 16 new studies in this update, the overall conclusions of the review remain unchanged. Zinc supplementation might help prevent episodes of diarrhea and improve growth slightly, particularly in children aged 6 months to 12 years of age. The benefits of preventive zinc supplementation may outweigh the harms in regions where the risk of zinc deficiency is relatively high.

Zinc supplementation prevents mitotic accumulation in human keratinocyte cell lines upon environmentally relevant arsenic exposure

Disrupted cell cycle progression underlies the molecular pathogenesis of multiple diseases. Chronic exposure to inorganic arsenic (iAs) is a global health issue leading to multi-organ cancerous and non-cancerous diseases. Exposure to supratherapeutic concentrations of iAs causes cellular accumulation in G2 or M phase of the cell cycle in multiple cell lines by inducing cyclin B1 expression. It is not clear if iAs exposure at doses corresponding to serum levels of chronically exposed populations (∼100 nM) has any effect on cell cycle distribution. In the present study we investigated if environmentally relevant iAs exposure induced cell cycle disruption and mechanisms thereof employing two human keratinocyte cell lines (HaCaT and Ker-CT), flow cytometry, immunoblots and quantitative real-time PCR (qRT-PCR). iAs exposure (100 nM; 24 h) led to mitotic accumulation of cells in both cell lines, along with the stabilization of ANAPC11 ubiquitination targets cyclin B1 and securin, without affecting their steady state mRNA levels. This result suggested that induction of cyclin B1 and securin is modulated at the level of protein degradation. Moreover, zinc supplementation successfully prevented iAs-induced mitotic accumulation and stabilization of cyclin B1 and securin without affecting their mRNA levels. Together, these data suggest that environmentally relevant iAs exposure leads to mitotic accumulation possibly by displacing zinc from the RING finger subunit of anaphase promoting complex/cyclosome (ANAPC11), the cell cycle regulating E3 ubiquitin ligase. This early cell cycle disruptive effect of environmentally relevant iAs concentration could underpin the molecular pathogenesis of multiple diseases associated with chronic iAs exposure.

Combined Diet and Supplementation Therapy Resolves Alopecia Areata in a Paediatric Patient: A Case Study

Alopecia areata (AA) is a common autoimmune condition resulting in spot baldness and, rarely, more extensive hair loss. There is an association between both the incidence and the severity of AA and several micronutrients, including vitamin D and zinc. This case reports an eight-year-old male diagnosed with AA and treated with a diet and supplemental regimen based on unrefined foods, rich in vitamins A and D, zinc, and supplemented with a multi-nutrient, zinc sulfate, and fish oil with vitamin D. Complete remission of AA was achieved within five months.

Percentile values of serum zinc concentration and prevalence of its deficiency in Iranian children and adolescents: the CASPIAN-V study

Background To determine the prevalence of serum zinc deficiency and provide the age- and sex-specific percentile values of serum zinc in children and adolescents. Methods We used the gathered data through the CASPIAN-V study, a national survey conducted on 3500 students aged 7-18 years from 30 provinces of Iran. In this study, 1370 blood samples were selected randomly, and serum zinc concentration was measured using a Hitachi automated analyzer. Zinc deficiency was defined as a serum zinc level of less than 75 μg/dL. Age-sex specific reference percentile values were developed for serum zinc concentration. Results The mean age of participants was 12.4 ± 3.0 years; 49.3% were girls and 73% were urban inhabitants. Mean (standard deviation [SD]) of serum zinc concentration was 107.23 (25.81) μg/dL with a significant sex difference; 109.03 ± 26.12 μg/dL for males compared to 105.41 ± 25.3 μg/dL for females (p = 0.009). The prevalence of subclinical zinc deficiency was 4.9% (95% confidence intervals [CI]: 3.0, 6.9) in children and adolescents. Both zinc deficient and sufficient groups were similar in terms of age, sex and residential areas (all p-value > 0.05). Overall, the 5th and 95th percentile values for serum zinc were 68.28 and 151.87 μg/dL, respectively. The value of all percentiles consistently decreased with age. The 10-99th percentile values for serum zinc were greater in boys than girls at all ages. Conclusions Nearly 5% of subjects had zinc deficiency. Age-sex specific percentile values were established for Iranian children and adolescents.

Bioelectrical Impedance Vector Analysis and Phase Angle on Different Oral Zinc Supplementation in Eutrophic Children: Randomized Triple-Blind Study

The parameters derived from bioelectrical impedance, phase angle (PA) and bioelectrical impedance vector analysis (BIVA) have been associated with cell membrane integrity and body cell mass. Zinc is a micronutrient that exerts important structural functions and acts in maintaining cellular functionality. To evaluate cell integrity and body cell mass, PA and BIVA were evaluated in children orally supplemented with zinc at different concentrations. Anthropometric, bioelectrical (resistance and reactance) and serum zinc variables were collected from two randomized, triple-blind, controlled clinical trials. Sampling was composed of 71 children consisting of three groups: a control group who received a placebo and two experimental groups who received oral supplementation of 5 or 10 mg-Zn/day for three months. The three groups presented increases (p < 0.001) in the linear height and weight. In the group supplemented with 10 mg-Zn/day, there was an increase in reactance values (p = 0.036) and PA (p = 0.002), in addition to vector displacement (p < 0.001) in relation to the confidence ellipses. An increase in serum zinc concentration was found (p < 0.001) in all three groups. Whit this, the supplementation with 10 mg-Zn/day promotes changes in the integrity of the cell membrane associated with the increase in the cellular mass of healthy children.

Dietary Supplement Use Among Chinese Primary School Students: A Cross-Sectional Study in Hunan Province

Dietary supplement use is increasing globally, especially among children. However, few studies have been conducted to examine dietary supplement use among Chinese children. The aim of this study was to examine the prevalence of dietary supplement use and the associated factors in primary school students. A cross-sectional study was conducted in four primary schools in Hunan province, China. A total of 706 Chinese parents/caregivers of school children aged 6–12 years old were enrolled. Self-administrated questionnaires were used to collect information about the children’s dietary supplement use, and their socio-demographic characteristics. The prevalence of dietary supplement use in primary school students was 20.4%. Calcium (16.7%), vitamin C (9.2%), and vitamin D (8.5%) were the most commonly used types of dietary supplement. The main reasons for parents/caregivers to purchase dietary supplements for their children were immunity improvement (43.6%), and for growth promotion (36.5%). Some caregivers (26.4%) purchased dietary supplements online, including from dubious or unknown sellers. However, 37.5% of caregivers did not receive formal guidance on supplementation even if they purchased their supplements through formal channels. Parents/caregivers were unclear about the appropriate choices for children’s dietary supplement use. Guidelines and counseling regarding dietary supplements for children may be helpful in public health work.