Coffee Consumption and Prostate Cancer Risk: A Meta-Analysis of Cohort Studies

This meta-analysis was conducted to assess the association between coffee consumption and prostate cancer risk. Thirteen cohort studies with 34,105 cases and 539,577 participants were included in the meta-analysis. The summary relative risks (RRs) with 95% confidence intervals (CIs) for different coffee intake levels were calculated. Dose-response relationship was assessed using generalized least square trend estimation. The pooled RR for the highest vs. lowest coffee intake was 0.90 (95% CI: 0.85–0.95), with no significant heterogeneity across studies (P = 0.267; I²= 17.5%). The dose-response analysis showed a lower cancer risk decreased by 2.5% (RR = 0.975; 95% CI: 0.957–0.995) for every 2 cups/day increment in coffee consumption. Stratifying by geographic region, there was a statistically significant protective influence of coffee on prostate cancer risk among European populations. In subgroup analysis of prostate cancer grade, the summary RRs were 0.89 (95% CI: 0.83–0.96) for nonadvanced, 0.82 (95% CI: 0.61–1.10) for advanced and 0.76 (95% CI: 0.55–1.06) for fatal diseases. Our findings suggest that coffee consumption may be associated with a reduced risk of prostate cancer and it also has an inverse association with nonadvanced prostate cancer. Because of the limited number of studies, more prospective studies with large sample size are needed to confirm this association.     

Tobacco smoking and the risk of sudden cardiac death: a systematic review and meta-analysis of prospective studies

Smoking is an established risk factor for cardiovascular disease including coronary heart disease and stroke, however, data regarding smoking and sudden cardiac death have not been summarized in a meta-analysis previously. We therefore conducted a systematic review and meta-analysis to clarify this association. We searched the PubMed and Embase databases for studies of smoking and sudden cardiac death up to July 20th 2017. Prospective studies were included if they reported adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) for smoking and sudden cardiac death. Summary RRs were estimated by use of a random effects model. Twelve prospective studies were included. The summary RR was 3.06 (95% CI 2.46–3.82, I² = 41%, p_{heterogeneity} = 0.12, n = 7) for current smokers and 1.38 (95% CI 1.20–1.60, I² = 0%, p_{heterogeneity} = 0.55, n = 7) for former smokers compared to never smokers. For four studies using non-current (never + former) smokers as the reference category the summary RR among current smokers was 2.08 (95% CI 1.70–2.53, I² = 18%, p_{heterogeneity} = 0.30). The results persisted in most of the subgroup analyses. There was no evidence of publication bias. These results confirm that smoking increases the risk of sudden cardiac death. Any further studies should investigate in more detail the effects of duration of smoking, number of cigarettes per day, pack-years, and time since quitting smoking and sudden cardiac death.     

Effects of Coffee,Black Tea and Green Tea Consumption on the Risk of Non-Hodgkin’s Lymphoma: A Systematic Review and Dose–Response Meta-Analysis of Observational Studies

Aim: Several studies have evaluated the association between coffee, black and green tea consumption and non-Hodgkin’s lymphoma (NHL) risk, while the results were inconsistent. We conducted a dose–response meta-analysis of available observational studies to assess the association among coffee, black and green tea intake and the risk of NHL in the general population.

Methods: Studies published up to August 2018 were identified on the basis of a literature search in PubMed, ISI Web of Science, Scopus and Cochrane databases using Mesh and non-Mesh relevant keywords. Relative risks (RRs) with 95% confidence intervals (CIs) and the dose–response relationships were calculated using random-effects models.

Results: In the meta-analysis of 19 effect sizes (315,972 participants with 4,914 cases of NHL), we found that higher green tea intake was associated with a 39% reduced risk of NHL (pooled RR?=?0.61; 95% CIs?=?0.38–0.99, I²=60.4%, p_{heterogeneity}=0.080) in high- versus low-intake meta-analysis. No association was observed between coffee intake (pooled RR?=?1.21; 95% CIs?=?0.97–1.50, I²=52.6%, p_{heterogeneity} < 0.05), black tea intake (pooled RR?=?1.01; 95% CI?=?0.82–1.24, I²=0%, p_{heterogeneity}=0.875) and risk of NHL in high- versus low-intake meta-analysis.

Conclusions: Findings from this dose–response meta-analysis suggest that green tea intake may be associated with reduced risk of NHL.     

Body mass index,abdominal fatness,weight gain and the risk of psoriasis: a systematic review and dose–response meta-analysis of prospective studies

Greater body mass index (BMI) has been associated with increased risk of psoriasis in case–control and cross-sectional studies, however, the evidence from prospective studies has been limited. We conducted a systematic review and dose–response meta-analysis of different adiposity measures and the risk of psoriasis to provide a more robust summary of the evidence based on data from prospective studies. PubMed and Embase databases were searched for relevant studies up to August 8th 2017. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random effects model. The summary relative risk (RR) for a 5 unit increment in BMI was 1.19 (95% CI 1.10–1.28, I² = 83%, n = 7). The association appeared to be stronger at higher compared to lower levels of BMI, p_nonlinearity < 0.0001, and the lowest risk was observed at a BMI around 20. The summary RR was 1.24 (95% CI 1.17–1.31, I² = 0%, p_{heterogeneity} = 0.72, n = 3) per 10 cm increase in waist circumference, 1.37 (95% CI 1.23–1.53, I² = 0%, p_{heterogeneity} = 0.93, n = 3) per 0.1 unit increase in waist-to-hip ratio, and 1.11 (95% CI 1.07–1.16, I² = 47%, p_{heterogeneity} = 0.15, n = 3) per 5 kg of weight gain. Adiposity as measured by BMI, waist circumference, waist-to-hip ratio, and weight gain is associated with increased risk of psoriasis.     

Dietary Carbohydrate and Prostate Cancer Risk: A Meta-Analysis

Carbohydrate intake has been inconsistently associated with risk of prostate cancer. We review and quantitatively summarize the evidence from observational studies in a meta-analysis. We searched the PubMed database for observational studies related to the association of carbohydrate intake and prostate cancer risk up to December 25, 2013. Summary relative risks (RRs) were estimated by the use of a random effects model. We included 13 case-control studies with 4,367 cases and 6,205 controls, and 5 cohort studies with 3,679 cases and 74,115 participants in this meta-analysis. The summary RR of prostate cancer for the highest vs. the lowest carbohydrate intake was 1.06 [95% confidence interval (CI): 0.93–1.20, I² = 46.8%] for all included studies. In the subgroup analyses stratified by study design, the summary RRs for the highest vs. the lowest carbohydrate intake were 1.04 (95% CI: 0.87–1.23) for case-control studies and 1.06 (95% CI: 0.88–1.28) for cohort studies. For the 5 studies that reported results for advanced prostate cancer, the summary RR was 0.92 (95% CI: 0.71–1.20). This meta-analysis of observational studies indicates that there is no association between carbohydrate intake and prostate cancer risk. Further studies are needed to confirm our findings.     

Effect of Coffee Consumption on Non-Alcoholic Fatty Liver Disease Incidence,Prevalence and Risk of Significant Liver Fibrosis: Systematic Review with Meta-Analysis of Observational Studies

Background and aim: Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. Given the anti-fibrotic and antioxidant properties of coffee, this systematic review and meta-analysis aims to provide updated results on the impact of coffee consumption on NAFLD incidence, prevalence, and risk of significant liver fibrosis. Methods: We conducted a comprehensive search in MEDLINE (OvidSP) and Scopus from January 2010 through January 2021. Relative risks for the highest versus the lowest level of coffee consumption were pooled using random-effects models. Heterogeneity and publication bias were evaluated using the Higgins’ I² statistic and Egger’s regression test, respectively. Results: Eleven articles consisting of two case-control studies, eight cross-sectional studies, and one prospective cohort study were included in the meta-analysis. Of those, three studies with 92,075 subjects were included in the analysis for NAFLD incidence, eight studies with 9558 subjects for NAFLD prevalence, and five with 4303 subjects were used for the analysis of liver fibrosis. There was no association between coffee consumption and NAFLD incidence (RR 0.88, 95% CI 0.63–1.25, p = 0.48) or NAFLD prevalence (RR 0.88, 95% CI 0.76–1.02, p = 0.09). The meta-analysis showed coffee consumption to be significantly associated with a 35% decreased odds of significant liver fibrosis (RR 0.65, 95% CI 0.54–0.78, p < 0.00001). There was no heterogeneity (I² = 11%, p = 0.34) and no evidence of publication bias (p = 0.134). Conclusion: This meta-analysis supports the protective role of coffee consumption on significant liver fibrosis in patients with NAFLD. However, the threshold of coffee consumption to achieve hepatoprotective effects needs to be established in prospective trials.     

Green Tea Consumption and Esophageal Cancer Risk: A Meta-analysis

Abstract

Background: The protective role of green tea against cancer is still unknown.

Objectives: To investigate the association between green tea consumption and esophageal cancer risk through meta-analysis.

Methods: We searched MEDLINE, EMBASE, Web of Science and Cochrane Library for studies on the relationship between green tea and esophageal cancer risk. We assessed heterogeneity (I²) and publication bias (Begg’s and Egger’s tests). Pooled relative risks (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random effects models.

Results: A total of 20 studies were included. The RRs for all studies was 0.65 (95% CI: 0.57–0.73), with I² = 75.3% and P?=?0. In the subgroup analysis, the following variables showed marked heterogeneity: Asian (RR: 0.64; 95% CI: 0.56–0.73) and non-Asian countries (RR: 0.74; 95% CI: 0.45–1.03), female (RR: 0.55; 95% CI: 0.39–0.71) and male?+?female (RR: 0.64; 95% CI: 0.54–0.75), case–control study (RR: 0.62; 95% CI: 0.52–0.71), impact factor >3 (RR: 0.65; 95% CI: 0.56–0.75), impact factor <3 (RR: 0.64; 95% CI: 0.48–0.80), Newcastle–Ottawa Scale >7 (RR: 0.82; 95% CI: 0.66–0.97) and Newcastle–Ottawa Scale ≤7 (RR: 0.59; 95% CI: 0.49–0.68).

Conclusion: Green tea consumption could be a protective factor for esophageal cancer.     

Body mass index and physical activity and the risk of diverticular disease: a systematic review and meta-analysis of prospective studies

Purpose

We conducted a systematic review and meta-analysis of prospective studies of the association between body mass index (BMI) and physical activity and diverticular disease risk.

Methods

PubMed and Embase databases were searched up to February 7, 2017. Summary relative risks and 95% confidence intervals (95% CIs) were calculated using a random effects model and nonlinear associations were modeled using fractional polynomial models.

Results

Six cohort studies of BMI and diverticular disease risk (28,915 cases, 1,636,777 participants) and five cohort studies of physical activity and diverticular disease risk (2080 cases, 147,869 participants) were included. The summary relative risk (RR) of incident diverticular disease for a 5 unit BMI increment was 1.28 (95% CI: 1.18–1.40, I ²?=?77%, n?=?6) for diverticular disease, 1.31 (95% CI: 1.09–1.56, I ²?=?74%, n?=?2) for diverticulitis, and 1.20 (95% CI: 1.04–1.40, I ²?=?56%, n?=?3) for diverticular disease complications. There was no evidence of a nonlinear association between BMI and diverticular disease risk (p _nonlinearity?=?0.22), and risk increased even within the normal weight range. Compared to a BMI of 20, the summary RR for a BMI of 22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, and 40.0 was 1.15 (1.07–1.23), 1.31 (1.17–1.47), 1.50 (1.31–1.71), 1.71 (1.52–1.94), 1.96 (1.77–2.18), 2.26 (2.00–2.54), 2.60 (2.11–3.21), and 3.01 (2.06–4.39), respectively. The summary RR was 0.76 (95% CI: 0.63–0.93, I ²?=?54%, n?=?5) for high vs. low physical activity and 0.74 (95% CI: 0.57–0.97, I ²?=?39.5%, p _{heterogeneity}?=?0.20, n = 2) for high vs. low vigorous physical activity.

Conclusions

These results suggest that even moderate increases in BMI may increase the risk of diverticular disease as well as diverticular disease complications and that a higher level of physical activity may reduce the risk.

     

Dose-response relation between serum total cholesterol levels and overall cancer risk: evidence from 12 prospective studies involving 1,926,275 participants

This study aimed to clarify the association between serum total cholesterol (TC) levels and overall cancer risk. Study-specific relative risks (RR) and 95% confidence intervals (CI) were pooled using a random-effects model, and dose–response relation was also evaluated. Twelve prospective studies were identified with a total of 1,926,275 participants and 13,1676 cases. High levels of serum TC showed an inverse association with overall cancer risk (RR for the highest versus the lowest category: 0.87, 95% CI: 0.83?～?0.90; I²?=?52.5%). A linear dose-response relation between serum TC levels and overall cancer risk was found (p?=?.004 for Wald test; I²?=?49.6%), and the pooled RR was 0.92 (95% CI: 0.89?～?0.94) for 3?mmol/L, 0.86 (95% CI: 0.81?～?0.90) for 5?mmol/L, 0.80 (95% CI: 0.74?～?0.87) for 7?mmol/L. Our dose-response meta-analysis of 12 prospective studies indicated that higher serum TC levels were significantly associated with reduced cancer risk.     

The Association of Dietary Quality Indices and Cancer Mortality: A Systematic Review and Meta-analysis of Cohort Studies

This study aimed to systematically review and do a meta-analysis on available evidence on the association of diet quality indices with cancer mortality. We searched for relevant papers published up to August 2017 through Web of science, PubMed/Medline, Scopus, and Google Scholar. Prospective cohort studies examined the association of any dietary quality indices with cancer mortality were included. Overall, 27 publications were included. There was significant inverse associations between the Dietary Approaches to Stop Hypertension (DASH) diet (HR: 0.85; 95% CI: 0.79, 0.91; I²?=?81.8%), the Alternative Healthy Eating Index (AHEI) (HR: 0.90; 95% CI: 0.85, 0.95; I²: 61.5), the healthy eating index (HEI) (RR: 0.82; 95% CI: 0.75, 0.89; I²: 89.5%) and cancer mortality. Significant associations with the lowest heterogeneity between Diet Quality Index (DQI) (HR: 0.91; 95% CI: 0.89–0.93, I²?=?0.0%), alternative Mediterranean Diet (aMED) (RR: 0.81; 95% CI: 0.78–0.83, I²?=?1.7%), and HEI-2010 (HR: 0.82; 95% CI: 0.69–0.98, I²?=?0.0%) and death due to cancer were also found. However, the Recommended Food Score, Dietary Diversity Score (DDS), and HEI-2005 were not related with cancer mortality. Adherence to DASH diet, AHEI, HEI, DQI, aMED, and HEI-2010 decreased the risk of cancer mortality.     

Consumption of red and processed meat and risk for esophageal squamous cell carcinoma based on a meta-analysis

PurposeTo provide a quantitative assessment of the association between red and processed meat intake and the risk of esophageal squamous cell carcinoma (ESCC), we summarized the evidence from observational studies.MethodsRelevant studies were identified in MEDLINE and EMBASE until October 31, 2012. Summary relative risks with 95% confidence intervals (CIs) were pooled with high versus low and linear dose-response random-effects models.ResultsA total of 21 studies (19 case-control and two cohort studies) with 6499 ESCC cases were included in this meta-analysis. Based on high versus low analysis, the summary relative risks of ESCC were 1.57 (95% CI, 1.26–1.95; P_{heterogeneity} = .003, I² = 56.0%) for red meat intake and 1.55 (95% CI, 1.22–1.97; P_{heterogeneity} = .029, I² = 45.3%) for processed meat intake. Subgrouped and sensitivity analyses revealed that the increment of ESCC risk with intakes of red meat and processed meat was stable and robust. These results are consistent with the results of the dose-response analyses. There was evidence of a nonlinear association of processed meat intake and ESCC risk (P_nonlinearity = .019).ConclusionsIntake of red and processed meat may be associated with significantly increased risk of ESCC. Further investigations with prospective designs are warranted.     

Fish,Long-Chain n-3 PUFA and Incidence of Elevated Blood Pressure: A Meta-Analysis of Prospective Cohort Studies

Results from prospective cohort studies on fish or long-chain (LC) n-3 polyunsaturated fatty acid (PUFA) intake and elevated blood pressure (EBP) are inconsistent. We aimed to investigate the summary effects. Pertinent studies were identified from PubMed and EMBASE database through October 2015. Multivariate-adjusted risk ratios (RRs) for incidence of EBP in the highest verses the bottom category of baseline intake of fish or LC n-3 PUFA were pooled using a random-effects meta-analysis. Over the follow-up ranging from 3 to 20 years, 20,497 EBP events occurred among 56,204 adults from eight prospective cohort studies. The summary RR (SRR) was 0.96 (95% CI: 0.81, 1.14; I² = 44.70%) for fish in four studies, and 0.73 (95% CI: 0.60, 0.89; I² = 75.00%) for LC n-3 PUFA in six studies (three studies for biomarker vs. three studies for diet). Circulating LC n-3 PUFA as biomarker was inversely associated with incidence of EBP (SRR: 0.67; 95% CI: 0.55, 0.83), especially docosahexaenoic acid (SRR: 0.64; 95% CI: 0.45, 0.88), whereas no significant association was found for dietary intake (SRR: 0.80; 95% CI: 0.58, 1.10). The present finding suggests that increased intake of docosahexaenoic acid to improve its circulating levels may benefit primary prevention of EBP.     

Cruciferous Vegetables Consumption and Risk of Renal Cell Carcinoma: A Meta-Analysis

Previous cohort and case-control studies on the association between cruciferous vegetables consumption and risk of renal cell carcinoma have illustrated conflicting results so far. To demonstrate the potential association between them, a meta-analysis was performed. Eligible studies were retrieved via both computerized searches and review of references. The summary relative risks (RRs) with 95% confidence interval (CI) for the highest vs. the lowest consumption of cruciferous vegetables were calculated. Heterogeneity and publication bias were also evaluated. Stratified analyses were performed as well. Three cohort and 7 case-control studies were included. A significantly decreased risk with renal cell carcinoma was observed in overall cruciferous vegetables consumption group (RR = 0.73; 95% CI, 0.63–0.83) and subgroup of case-control studies (RR = 0.69; 95% CI, 0.60–0.78), but not in cohort studies (RR = 0.96; 95% CI, 0.71–1.21). No heterogeneity and publication bias were detected across studies. Our findings supported that cruciferous vegetables consumption was related to the decreased risk of renal cell carcinoma. Because of the limited number of studies, further well-designed prospective studies and researches need to be conducted to better clarify the protective effect of cruciferous vegetables on renal cell carcinoma and potential mechanism.     

Fish Consumption and Lung Cancer Risk: Systematic Review and Meta-Analysis

There is evidence pointing to a possible role of diet on cancer etiology. Prior studies evaluating the relationship between fish consumption and lung cancer risk reported inconclusive results. The aim of this study was to achieve a comprehensive assessment of the relationship between fish consumption and lung cancer risk through systematic review and meta-analysis. Case control and cohort studies up to September 1, 2012 about fish consumption and lung cancer risk were confirmed by an online search. Separate relative risk (RR) or odds ratio (OR) estimates with 95% confidence interval (CI) of the relationship between lung cancer risk and fish consumption level from the included articles were combined by Stata11.0 software. Publication bias was evaluated by Egger's linear regression test and funnel plot. Twenty articles (17 case-control and 3 cohort studies) comprising 8799 cases of lung cancer and 17,072 noncases were included in the final analysis. The pooled results from all studies indicated that high fish consumption was significantly associated with a decreased risk of lung cancer (pooled RR: 0.79; 95% CI: 0.69–0.92). There was heterogeneity among the studies (I² = 73%, P < 0.05). Pooled RR in case control and cohort studies were 0.76 (95% CI: 0.63–0.91) and 0.95 (95% CI: 0.73–1.24), respectively. Omission of any single study had little effect on the combined risk estimates. This article had no publication bias. This study identifies a significant association between fish consumption and lung cancer, confirming a protective role of fish in lung cancer. More well-designed prospective studies are required to further verify the effect of fish consumption on lung cancer.     

Japanese-Style Diet and Cardiovascular Disease Mortality: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

This systematic review and meta-analysis elucidate the effects of the Japanese-style diet and characteristic Japanese foods on the mortality risk of cardiovascular disease (CVD), cerebrovascular disease (stroke), and heart disease (HD). This review article followed the PRISMA guidelines. A systematic search in PubMed, The Cochrane Library, JDreamIII, and ICHUSHI Web identified prospective cohort studies on Japanese people published till July 2020. The meta-analysis used a random-effects model, and heterogeneity and publication bias were evaluated with I² statistic and Egger’s test, respectively. Based on inclusion criteria, we extracted 58 articles, including 9 on the Japanese-style diet (n = 469,190) and 49 (n = 2,668,238) on characteristic Japanese foods. With higher adherence to the Japanese-style diet, the pooled risk ratios (RRs) for CVD, stroke, heart disease/ischemic heart disease combined (HD/IHD) mortality were 0.83 (95% CI, 0.77–0.89, I² = 58%, Egger’s test: p = 0.625, n = 9 studies), 0.80 (95% CI, 0.69–0.93, I² = 66%, Egger’s test: p = 0.602, n = 6 studies), and 0.81 (95% CI, 0.75–0.88, I² = 0%, Egger’s test: p = 0.544, n = 6 studies), respectively. Increased consumption of vegetables, fruits, fish, green tea, and milk and dairy products decreased the RR for CVD, stroke, or HD mortality. Increased salt consumption elevated the RR for CVD and stroke mortality. Increased consumption of dietary fiber and plant-derived protein decreased the RR for CVD, stroke, and HD/IHD mortality. The Japanese-style diet and characteristic Japanese foods may reduce CVD mortality. Most studies conducted diet surveys between 1980 and the 1990s. This meta-analysis used articles that evaluated the same cohort study by a different method. A new large-scale cohort study matching the current Japanese dietary habits is needed to confirm these findings.     

Coffee and caffeine intake and risk of endometriosis: a meta-analysis

Purpose

The potential association between endometriosis and coffee/caffeine consumption has been analysed in several epidemiological studies. In order to establish whether caffeine influences the risk of endometriosis, we provide to summarize the evidence from published studies on this issue.

Methods

We performed a meta-analysis of epidemiological studies published up to January 2013. We computed summary relative risks (RR) of endometriosis for any, high and low versus no coffee/caffeine consumption.

Results

We identified a total eight studies, six case–control and two cohort studies, including a total of 1,407 women with endometriosis. The summary RR for any versus non-consumption were 1.26 [95 % confidence interval (CI) 0.95–1.66] for caffeine and 1.13 (95 % CI 0.46–2.76) for coffee consumption; the overall estimate was 1.18 (95 % CI 0.92–1.49). The summary RR were 1.09 (95 % CI 0.84–1.42) and 1.09 (95 % CI 0.89–1.33) for high and low caffeine consumption as compared to no consumption, respectively.

Conclusion

The present meta-analysis provided no evidence for an association between coffee/caffeine consumption and the risk of endometriosis. Coffee/caffeine consumption, as currently used in diet, does not carry a health risk.     

Body fatness,diabetes, physical activity and risk of kidney stones: a systematic review and meta-analysis of cohort studies

We conducted a systematic review and meta-analysis to clarify the association between adiposity, diabetes, and physical activity and the risk of kidney stones. PubMed and Embase were searched up to April 22nd 2018 for relevant studies. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random effects models. Thirteen cohort studies were included. The summary relative risk was 1.21 (95% CI 1.12–1.30, I²?=?76%, n?=?8) per 5 unit increment in BMI, 1.16 (95% CI 1.12–1.19, I²?=?0%, n?=?5) per 10 cm increase in waist circumference, 1.06 (95% CI 1.04–1.08, I²?=?67%, n?=?3) per 5 kg increase in weight and 1.12 (95% CI 1.06–1.18, I²?=?86%, n?=?3) per 5 kg of weight gain. The summary RR was 1.16 (95% CI 1.03–1.31, I²?=?51%, n?=?10) for participants with diabetes compared to participants without diabetes, and 0.93 (95% CI 0.78–1.10, I²?=?80%, n?=?4) for high vs. low physical activity. These results suggest a positive association between adiposity and diabetes and the risk of kidney stones, but no association with physical activity.     

Physical activity and the risk of gestational diabetes mellitus: a systematic review and dose–response meta-analysis of epidemiological studies

Physical activity has been inconsistently associated with risk of gestational diabetes mellitus in epidemiological studies, and questions remain about the strength and shape of the dose–response relationship between the two. We therefore conducted a systematic review and meta-analysis of cohort studies and randomized trials on physical activity and gestational diabetes mellitus. PubMed, Embase and Ovid databases were searched for cohort studies, and randomized controlled trials of physical activity and risk of gestational diabetes mellitus, up to August 5th 2015. Summary relative risks (RRs) were estimated using a random effects model. Twenty-five studies (26 publications) were included. For total physical activity the summary RR for high versus low activity was 0.62 (95 % CI 0.41–0.94, I² = 0 %, n = 4) before pregnancy, and 0.66 (95 % CI 0.36–1.21, I² = 0 %, n = 3) during pregnancy. For leisure-time physical activity the respective summary RRs for high versus low activity was 0.78 (95 % CI 0.61–1.00, I² = 47 %, n = 8) before pregnancy, and it was 0.80 (95 % CI 0.64–1.00, I² = 17 %, n = 17) during pregnancy. The summary RR for pre-pregnancy activity was 0.70 (95 % CI 0.49–1.01, I² = 72.6 %, n = 3) per increment of 5 h/week and for activity during pregnancy was 0.98 (95 % CI 0.87–1.09, I² = 0 %, n = 3) per 5 h/week. There was evidence of a nonlinear association between physical activity before pregnancy and the risk of gestational diabetes mellitus, p_nonlinearity = 0.005, with a slightly steeper association at lower levels of activity although further reductions in risk were observed up to 10 h/week. There was also evidence of nonlinearity for physical activity in early pregnancy, p_nonlinearity = 0.008, with no further reduction in risk above 8 h/week. There was some indication of inverse associations between walking (before and during pregnancy) and vigorous activity (before pregnancy) and the risk of gestational diabetes mellitus. This meta-analysis suggests that there is a significant inverse association between physical activity before pregnancy and in early pregnancy and the risk of gestational diabetes mellitus. Further studies are needed to clarify the association between specific types and intensities of activity and gestational diabetes mellitus.     

Relationship Between Serum Zinc Level and Metabolic Syndrome: A Meta-Analysis of Observational Studies

ABSTRACT

Objective: This research sought to summarize the evidence regarding the relationship between serum zinc level and metabolic syndrome (MetS).

Methods: The electronic databases of PubMed, Web of Science, and Embase were searched up to October 2017 for observational studies on the association between serum zinc level and MetS. The standard mean difference (SMD) and its corresponding 95% confidence interval (CI) of the serum zinc level for MetS versus control participants were calculated. In addition, the pooled odds ratio (OR) and relative risk (RR) of MetS for the highest versus lowest category of serum zinc level, as well as their corresponding 95% CI, were also calculated.

Results: A total of 11 observational studies (8 cross-sectional, 1 case-control, and 2 cohort studies) were included in this meta-analysis. The combined SMD demonstrated that the serum zinc level in MetS was higher than that in control participants (SMD = 0.11; 95% CI, 0.03–0.19; p = 0.009). Moreover, the overall multivariable-adjusted RR showed that the increased serum zinc level was associated with a higher risk of MetS (RR = 1.82; 95% CI, 1.33–2.50; p < 0.001). On the contrary, the overall multivariable-adjusted OR showed that there was no significant relationship between serum zinc level and MetS (OR = 1.00; 95% CI, 0.99–1.01; p = 0.841).

Conclusions: Although the serum zinc level in participants with MetS was significantly higher than that in control ones, the existing evidence was still insufficient to conclude a definite relationship between serum zinc level and MetS. More well-designed prospective cohort studies are needed to elaborate the concerned issues further.     

Personal hair dye use and bladder cancer: a meta-analysis

Despite considerable research, the issue of hair dyes and bladder cancer is still open to discussion. In January 2013, we searched in PubMed/EMBASE to identify observational studies investigating the association between personal use of hair dyes and bladder cancer incidence/mortality. Pooled relative risks (RRs) and corresponding 95% confidence intervals (CIs) were calculated using random-effects models. Fifteen case-control and two cohort studies were available for meta-analysis (8504 cases/deaths, 14,102 controls, and 617,937 persons at risk). Compared with no use, the pooled RR of bladder cancer for personal use of any type of hair dyes was 0.93 (95% CI, 0.82–1.05), with moderate heterogeneity among studies (I² = 34.1%, P = .07). Similar RRs were found for females (RR = 0.95) and males (RR = 0.81). Based on seven studies, the pooled RR for personal use of permanent hair dyes was 0.92 (95% CI, 0.77–1.09). Compared with no use, no association was observed for the highest categories of duration of use and lifetime frequency of use of both any type of dyes and permanent dyes. The pooled RR from four studies reporting results for use of dark-colored dyes was 1.29 (95% CI, 0.98–1.71). This meta-analysis allows to definitively exclude any appreciable excess risk of bladder cancer among personal hair dye users.