Effect of zinc supplementation on blood sugar control in the overweight and obese population: A systematic review and meta-analysis of randomized controlled trials

BackgroundAlthough overweight and obese people have a higher risk of type 2 diabetes incidence than normal-weight individuals, the efficacy of zinc supplementation in blood sugar control in overweight and obese people remained unknown. This meta-analysis attempted to address this issue.MethodsDatabases including PubMed, Embase, and the Cochrane Library were searched from inception until May 2022 to identify randomized controlled trials (RCTs) investigating the effects of zinc supplementation among participants who were overweight or obese without language restriction. It is a random-effect meta-analysis that analyzed the impact of zinc supplementation on fasting glucose (FG) (i.e., primary outcome) and other variables including fasting insulin (FI), homeostasis model assessment-insulin resistance index (HOMA-IR), glycated hemoglobin (HbA1c), high-sensitivity C-reactive protein (hs-CRP), and 2-hour postprandial glucose (2 h- PG).ResultsAnalysis of 12 eligible RCTs involving 651 overweight/obese participants demonstrated that zinc supplementation significantly improves FG (weighted mean difference [WMD]: −8.57 mg/dL; 95% confidence interval [CI]: −14.04 to −3.09 mg/dL, p = 0.002), HOMA-IR (WMD: −0.54; 95% CI: −0.78 to −0.30, p < 0.001), HbA1c (WMD: −0.25%; 95% CI: −0.43% to −0.07%, p = 0.006), and 2 h-PG (WMD: −18.42 mg/dL; 95% CI: −25.04 to −11.79 mg/dL, p < 0.001) compared to those in the control group. After conducting subgroup analyses, we found that the primary outcome, FG, showed more significant results in the subgroups with Asia, Zinc supplementation alone, higher dose (≥30 mg) and patients with diabetes.ConclusionOur meta-analysis indicated that zinc supplementation benefits blood sugar control in overweight and obese populations, with an especially significant reduction in FG.     

生活方式干预改善超重及肥胖青少年氧化应激状态

目的超重和肥胖已成为影响青少年健康的关键问题。本研究探讨饮食及运动干预对青少年体内氧化应激状态的影响。方法124名受试者中的93名超重及肥胖青少年年龄（13．6±0．7）岁,体重指数（BMI22．4～34．1kg／m。）随机分为四组：饮食干预组（D）、运动干预组（E）、饮食运动干预组（DE）、超重及肥胖对照组（O）。饮食方案根据研究对象的年龄及理想体重制定;运动干预为放学后1h中等强度运动,每周4次。干预周期为10周,干预前后分别进行人体测量、身体成分、代谢及氧化应激等指标检测。31名正常体重者为对照组。结果超重及肥胖组的空腹血糖、TC、LDL—C和MDA水平明显高于正常体重组（P〈0．05）,SOD水平低于正常体重组（P〈0．05）;MDA水平与体重、BMI、TC、LDL-C呈正相关（R=0．209,0．228,0．274,0．263,P〈0．05）,SOD与体重及BMI呈负相关（R=一0．334,一0．362,P〈0．05）;干预后D、E、DE组BMI、腰围、全身脂肪显著下降（P〈0．05）,D和E组的MDA水平下降（P〈0．05）;两个运动干预组的TC和LDL—C下降亦达统计学差异（P〈0．05）。结论超重青少年在糖脂代谢正常阶段体内即存在氧化应激失衡状态。为期10周的饮食和（或）运动的生活方式干预在改善青少年超重状态、调节血脂水平的同时,还可显著降低其体内的氧化应激水平。     

Skipping breakfast is associated with overweight and obesity: A systematic review and meta-analysis

ObjectiveIn recent years, many original studies have shown that skipping breakfast has been associated with overweight and obesity; however, the results of different studies are inconsistent. Therefore, we conducted a systematic review and meta-analysis of observational studies to synthesize the associations between skipping breakfast and the risk of overweight/ obesity.MethodsWe did a systematic search using Pubmed, and Ovid searched up to August 2019. Observational studies (cohort studies and cross-sectional studies) reporting adjusted Odds Ratio or Risk Ratio estimates for the association between breakfast skipping and overweight/obesity (including abdominal obesity). Summary odds ratio (or Risk Ratio) and 95% confidence intervals calculated with a random-effects model.Results45 observational studies (36 cross-sectional studies and 9 cohort studies) were included in this meta-analysis. In cross-sectional studies, The ORs of low frequency breakfast intake per week versus high frequency were 1.48 (95% CI 1.40–1.57; I² = 54.0%; P = 0.002) for overweight/obesity, 1.31 (95% CI 1.17–1.47; I² = 43.0%; P = 0.15) for abdominal obesity. In cohort studies, The RR of low-frequency breakfast intake per week versus high frequency was 1.44 (95% CI 1.25–1.66; I² = 61%; P = 0.009) for overweight/obesity.ConclusionsThis meta-analysis confirmed that skipping breakfast is associated with overweight/obesity, and skipping breakfast increases the risk of overweight/obesity. The results of cohort studies and cross-sectional studies are consistent. There is no significant difference in these results among different ages, gender, regions, and economic conditions.     

Effectiveness of interventions aiming at reducing sedentary behaviour in a non-surgical population with overweight or obesity: A systematic review and meta-analysis

AimThis systematic review and meta-analyses of randomised controlled trials (RCTs) investigated the effectiveness of interventions to reduce sedentary behaviour amongst people with overweight or obesity. Secondarily, it aimed to investigate the effectiveness of these interventions on body mass index (BMI), time spent in moderate-to-vigorous physical activity (MVPA) and health-related quality of life (HRQoL).MethodsA search of six databases (CENTRAL, PubMed, Embase, PEDro, CINAHL and PsycINFO) was conducted from inception to July 2018. RCTs in which sedentary behaviour was measured by accelerometry or inclinometry, with participants of any age with overweight or obesity were included. Subgroup analyses were undertaken comparing studies that included adults versus children and studies with an active component (e.g., treadmill desk, physically active breaks) versus no active component to their intervention.ResultsNine studies (n = 1859) were included. Compared to the control group, the interventions significantly reduced time spent in sedentary behaviour (standardised mean difference [95% confidence interval] ?0.33 [?0.59 to ?0.08] overall; ?0.53 [?0.95 to ?0.11] in adults). Subgroup analyses demonstrated that only interventions that included active components reduced time spent in sedentary behaviour (?0.54 [?0.88 to ?0.20]) and increased time spent in MVPA (1.29 [0.02 to 2.56]). Subgroup analyses demonstrated that interventions only reduced BMI in studies of children (?0.09 [?0.18 to ?0.00]) and in those with no active component (?0.09 [?0.18 to ?0.01]). There were insufficient data to investigate the effectiveness of these interventions on HRQoL.ConclusionsThis novel systematic review and meta-analyses suggests interventions aiming to effectively reduce objectively-measured sedentary behaviour need to specifically include an active component.     

Visceral adiposity index is positively associated with blood pressure: A systematic review

PurposeThis systematic review aimed to investigate the association between VAI and blood pressure.MethodsThe study was according to the PRISMA standards and the bibliographic search in the PubMed, EMBASE and Cochrane Library databases.ResultsThis review included 32 articles, with 60,482 individuals – children to elderly people between 7 and 102 years old – of different age groups, most of them female (54.9%; n = 26,478). The year of publication ranged from 2010 to 2020, indicating that it is a recent theme, applied in almost all continents (America, Europe, Africa and Asia). The authors used data as continuous or into quantiles; blood pressure data also varied, with different cutoff points for the classification of arterial hypertension or continuously. The vast majority of studies have shown a positive association between VAI and blood pressure, both the sexes, in different age groups. The evaluation of the quality of the articles used by the Tool of the Joanna Briggs Institute according to their design.ConclusionIndividuals with increased VAI have higher blood pressure levels. Registration (PROSPERO: CRD42020205965).     

Trend in the prevalence of obesity and overweight among Iranian children and adolescents: A systematic review and meta-analysis

ObjectiveChildhood obesity is an important predisposing factor for most non-communicable diseases. The aim of this review was to provide evidence on the prevalence and trends of childhood obesity and overweight in Iran.MethodsMultiple international and Iranian scientific databases were searched for relevant literatures. Two independent reviewers identified relevant papers in several steps. Separate meta-analyses (using fixed- or random-effect models) were performed to estimate the overall, age, sex, and age–sex specific prevalence of obesity and overweight. Stratified analysis based on Centers for Disease Control and Prevention, International Obesity Task Force, and World Health Organization definition criteria and study year also were performed.ResultsWe included 107 studies in the meta-analysis (49 English and 58 Persian). Based on Centers for Disease Control and Prevention definition criteria, the overall prevalence of obesity and overweight remained relatively constant in the 2000s and are estimated to be about 5.1% (95% confidence interval [CI], 4.4–5.8) and 10.8% (95% CI, 10.2–11.4), respectively. The meta-regression analysis showed that the prevalence of obesity and overweight did not vary significantly with respect to sex and age of study participants. Girls had a lower prevalence of obesity and higher prevalence of overweight than boys.ConclusionThis review, which is the first of its kind in the Middle East and North Africa, suggests that although the trend in the prevalence of childhood obesity in Iranian children is not considerably high, but the escalating trend of excess weight among young children is alarming and should be considered by providers of interventional preventive programs at national and regional levels.     

健康体检超重人群体质指数与部分健康指标关系研究

目的 研究合肥市健康体检人群体质指数（BMI）及其与血压、血糖、血脂、血尿酸的关系.方法 对3 640例健康体检者BMI分析,探讨超重、肥胖与血压、血糖、血脂及血尿酸水平变化.结果 该人群的平均BMI为（25.47±2.83）kg/m2,其中男性（26.33±2.48）kg/m2高于女性（23.91±2.75）kg/m2;BMI在各年龄组差异有统计学意义（P＜0.05）.不同BMI分层组中血压、血糖、血脂及血尿酸水平有显著差异,不同性别及年龄组BMI中血压、血糖、血脂及血尿酸水平有显著差异.结论 不同性别及年龄组BMI中血压、血糖、血脂及血尿酸水平差异较大,控制体重对高血压、高血糖、高血脂及高血尿酸等慢性病的防治具有重要意义.     

口服α一硫辛酸对超重或肥胖患者脉搏波速度和卧位血压影响的随机、双盲、安慰剂对照、交叉试验研究

目的 探讨超重或肥胖患者口服抗氧化剂α-硫辛酸(ALA)对臂踝脉搏波速度(baPWV)、卧位收缩压(sSBP)和卧位舒张压(sDBP)的影响,为超重或肥胖相关心血管疾病的预防提供理论依据.方法 采用随机、双盲、安慰剂对照和交叉试验设计.按照入选标准(20～60岁汉族、BMI≥25 kg/m2和未服用任何抗氧化剂等)纳入研究对象103人(男性63人、女性40人).采用分层区组随机化设计方法将研究对象随机分到ALA组(52人)或安慰剂组(51人)进行为期8周的干预,剂量为1200mg/d.经过4周洗脱期后,两组干预措施交换再干预8周.基线测量包括问卷调查、人体测量、血压测量、脉搏波速度、卧位血压、血液生化指标的检测.两阶段起始和终末均采用统一的检测方法和同一批调查员.采用Stata 11.0软件进行混合效应模型分析.结果 ALA组和安慰剂组人体测量指标和生化指标的基线水平均衡可比(P＞0.05).经口服ALA 8周后,ALA组baPWV降低(-33.03±130.70)cm/s,安慰剂组升高(5.66±139.89)cm/s,两组差异无统计学意义(P=0.078).ALA组sSBP降低(-4.09±9.18)mm Hg,安慰剂组降低(-2.32±8.16)mm Hg,两组差异无统计学意义(P=0.067);ALA组sDBP降低(-1.29±6.55)mm Hg,安慰剂组降低(-0.48±6.63)mm Hg,但两组差异无统计学意义(P=0.595).混合效应模型分析结果显示,在控制了试验顺序、阶段等因素后,两组间baPWV、sSBP和sDBP的差异均无统计学意义.结论 ALA 1200mg/d口服8周,不能明显降低动脉硬度和卧位血压水平.

Abstract：

Objective To investigate the effect of oral alpha-lipoic acid (ALA) supplement on brachial-ankle pulse wave velocity (baPWV),supine systolic blood pressure (SBP) and diastolic blood pressure (DBP) in overweight/obese individuals.An 8-week double-blind,randomized,placebo-controlled and cross-over trial with a 4-week washout between cross-over periods.Methods Sixty-three males and 40 females aged 22-57 years old who met the inclusion criteria as (1) Han ethnicity;(2) 20-60 years old;(3) BMI≥25 kg/m2 and having at least one of the following risk factors:borderline hypertension (130 mm Hg≤SBP＜140 mm Hg and/or 85 mm Hg≤supine DBP＜90 mm Hg),dyslipidemia(fasting total cholesterol≥5.2 mmol/L or HDL-C＜1.04 mmol/L),or impaired fasting glucose (6.1 mmol/L≤fasting glucose＜7.0 mmol/L);(4)Not on any antioxidant gender.Group 1 received 8 weeks ALA (1200 mg/day) followed by 4-week washout period and followed by another 8 weeks placebo;while Group 2 received 8 weeks placebo (1200 mg/day)followed by 4-week washout period,and followed by ALA treatment for 8 weeks.BaPWV and supine blood pressure were measured at the beginning of 1st phase and 2nd phase and at the endpoint of the whole trial.Mixed effect linear regression model was performed to compare the change of baPWV and supine blood pressure between ALA group and placebo group.Results BaPWV decreased -33.03 cm/s ± 130.70 cm/s for ALA group and increased 5.66 cm/s ± 139.89 cm/s for placebo group,supine systolic blood pressure decreased -4.09 mm Hg±9.18 mm Hg for ALA group and -2.32 mm Hg±8.16 mm Hg for placebo group.Supine diastolic blood pressure decreased -1.29 mm Hg ± 6.55 mm Hg for ALA group and -0.48 mm Hg±6.63 mm Hg for placebo group.These three mix-effect models did not show significant effect of ALA treatment after adjustment on baseline values,sex,age,treatment sequence or period.Conclusion The current trial did not provide evidence that oral intake of ALA for 8 weeks had significant effects on lowering baPWV,supine systolic blood pressure or supine diastolic blood pressure.