Effects of Metabolic Syndrome on Semen Quality and Circulating Sex Hormones: A Systematic Review and Meta-Analysis.
ABSTRACT: Previous studies were controversial in the effects of metabolic syndrome (MetS) on semen quality and circulating sex hormones, and thus we conducted a systematic review and meta-analysis to clarify the association. A systematic search was conducted in public databases to identify all relevant studies, and study-specific standardized mean differences (SMD) and 95% confidence intervals (CI) were pooled using a random-effects model. Finally, 11 studies were identified with a total of 1,731 MetS cases and 11,740 controls. Compared with the controls, MetS cases had a statistically significant decrease of sperm total count (SMD: -0.96, 95% CI: -1.58 to -0.31), sperm concentration (SMD: -1.13, 95% CI: -1.85 to -0.41), sperm normal morphology (SMD: -0.61, 95% CI: -1.01 to -0.21), sperm progressive motility (SMD: -0.58, 95% CI: -1.00 to -0.17), sperm vitality (SMD: -0.83, 95% CI: -1.11 to -0.54), circulating follicle-stimulating hormone (SMD: -0.87, 95% CI: -1.53 to -0.21), testosterone (SMD: -5.61, 95% CI: -10.90 to -0.31), and inhibin B (SMD: -2.42, 95% CI: -4.52 to -0.32), and a statistically significant increase of sperm DNA fragmentation (SMD: 0.76, 95% CI: 0.45 to 1.06) and mitochondrial membrane potential (SMD: 0.89, 95% CI: 0.49 to 1.28). No significant difference was found in semen volume, sperm total motility, circulating luteinizing hormone (LH), estradiol, prolactin and anti-Müllerian hormone (AMH) (P > 0.05). In conclusion, this meta-analysis demonstrated the effects of MetS on almost all the semen parameters and part of the circulating sex hormones, and MetS tended to be a risk factor for male infertility. Further larger-scale prospective designed studies were needed to confirm our findings.
Project description:BACKGROUND: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is one of the risk factors of impaired male fertility potential. Studies have investigated the effect of CP/CPPS on several semen parameters but have shown inconsistent results. Hence, we performed a systematic literature review and meta-analysis to assess the association between CP/CPPS and basic semen parameters in adult men. METHODS: Systematic literature searches were conducted with PubMed, EMBASE and the Cochrane Library up to August 2013 for case-control studies that involved the impact of CP/CPSS on semen parameters. Meta-analysis was performed with Review Manager and Stata software. Standard mean differences (SMD) of semen parameters were identified with 95% confidence intervals (95% CI) in a random effects model. RESULTS: Twelve studies were identified, including 999 cases of CP/CPPS and 455 controls. Our results illustrated that the sperm concentration and the percentage of progressively motile sperm and morphologically normal sperm from patients with CP/CPPS were significantly lower than controls (SMD (95% CI) -14.12 (-21.69, -6.63), -5.94 (-8.63, -3.25) and -8.26 (-11.83, -4.66), respectively). However, semen volume in the CP/CPPS group was higher than in the control group (SMD (95% CI) 0.50 (0.11, 0.89)). There was no significant effect of CP/CPPS on the total sperm count, sperm total motility, and sperm vitality. CONCLUSIONS: The present study illustrates that there was a significant negative effect of CP/CPPS on sperm concentration, sperm progressive motility, and normal sperm morphology. Further studies with larger sample sizes are needed to better illuminate the negative impact of CP/CPPS on semen parameters.
Project description:Ageing is associated with reduced appetite and energy intakes. However, the mechanisms underlying this phenomenon are not fully understood. This systematic review and meta-analysis quantified differences in circulating concentrations of appetite-related hormones between healthy older and younger adults. Six databases were searched through 12th June 2018 for studies that compared appetite-related hormone concentrations between older and younger adults. Data were pooled using random-effects meta-analysis and are presented as standardised mean difference (Hedges' g) with 95% confidence intervals (95% CI). Thirty-five studies were included involving 710 older adults (mean?±?SD; age: 73?±?5 years) and 713 younger adults (age: 28?±?7 years). Compared with younger adults, older adults exhibited higher fasted and postprandial concentrations of the anorectic hormones cholecystokinin (Fasted: SMD 0.41 (95% CI 0.24, 0.57); p?<?0.001. Postprandial: SMD 0.41 (0.20, 0.62); p?<?0.001), leptin [Fasted: SMD 1.23 (0.15, 2.30); p?=?0.025. Postprandial: SMD 0.62 (0.23, 1.01); p?=?0.002] and insulin [Fasted: SMD 0.24 (-?0.02, 0.50); p?=?0.073. Postprandial: SMD 0.16 (0.01, 0.32); p?=?0.043]. Higher postprandial concentrations of peptide-YY were also observed in older adults compared with younger adults [SMD 0.31 (-?0.03, 0.65); p?=?0.075]. Compared with younger adults, older adults had lower energy intakes [SMD -?0.98 (-?1.74, -?0.22); p?=?0.011], and lower hunger perceptions in the fasted [SMD -?1.00 (-?1.54, -?0.46); p?<?0.001] and postprandial states [SMD -?0.31, (-?0.64, 0.02); p?=?0.064]. Higher circulating concentrations of insulin, leptin, cholecystokinin and peptide-YY accord with reduced appetite and energy intakes in healthy older adults. Interventions to reduce circulating levels of these hormones may be beneficial for combatting the anorexia of ageing.
Project description:BACKGROUND:Human papillomavirus (HPV) has been considered as one of the most common sexually transmitted viruses that may be linked to unexplained infertility in men. The possible mechanisms underlying correlation between HPV infection and infertility could be related to the altered sperm parameters. Current studies have investigated the effect of HPV seminal infection on sperm quality in infertile men, but have shown inconsistent results. METHODS:We systematically searched PubMed, Embase, Web of Science and CNKI for studies that examined the association between HPV seminal infection and sperm progressive motility. Data were pooled using a random-effects model. Outcomes were the sperm progressive motility rate. Results are expressed as standardised mean difference (SMD) with 95% confidence interval (CI). Heterogeneity was evaluated by the I-square (I2) statistic. RESULTS:Ten studies were identified, including 616 infertile patients with HPV seminal infection and 2029 infertile controls without HPV seminal infection. Our meta-analysis results indicated that sperm progressive motility was significantly reduced in HPV-infected semen samples compared with non-infected groups [SMD:-0.88, 95% CI:-1.17?~?-?0.59]. There existed statistical heterogeneity (I2 value: 86%) and the subgroup analysis suggested that study region might be the causes of heterogeneity. CONCLUSIONS:HPV semen infection could significantly reduce sperm progressive motility in infertile individuals. There were some limitations in the study such as the differences in age, sample sizes and the number of HPV genotypes detected. Further evidences are needed to better elucidate the relationship between HPV seminal infection and sperm quality.
Project description:Chronic bacterial prostatitis (CBP) is caused by bacterial infection and maintains a condition of lower urinary tract infection. It may be a cause of male infertility. However, studies showed inconsistent results regarding the effect of CBP on several parameters of semen. Hence, we conducted a meta-analysis to examine the effect of CBP on basic semen parameters. A systematic review was conducted with Medline, PubMed, EMBASE, and two Chinese databases (CNKI and WANG FANG) to identify relevant studies that involved the effect of CBP on semen parameters up to July 2014. Both RevMan5.2 and STATA 12.0 software were used for the statistical analysis. Based on the inclusion and exclusion criteria, seven studies were included. The study illustrated that sperm vitality, sperm total motility, and the percentage of progressively motile sperm from CBP patients were significantly lower than controls (SMD(95%CI) -0.81[-1.14, -0.47], -1.00[-1.28, -0.73], -0.41 [-0.70, -0.12], P<0.05, respectively). However, CBP had no significant effect on semen volume, sperm concentration and the duration of semen liquefaction. In summary, our study revealed that there was a significant negative effect of CBP on sperm vitality, sperm total motility, and the percentage of progressively motile sperm. Additional, studies with larger number of subjects are needed.
Project description:Zinc is an essential trace mineral for the normal functioning of the male reproductive system. Current studies have investigated the relationship between seminal plasma zinc and male infertility but have shown inconsistent results. Hence, we systematically searched PubMed, EMBASE, Science Direct/Elsevier, CNKI and the Cochrane Library for studies that examined the relationship between seminal plasma zinc and male infertility, as well as the effects of zinc supplementation on sperm parameters. Twenty studies were identified, including 2,600 cases and 867 controls. Our meta-analysis results indicated that the seminal plasma zinc concentrations from infertile males were significantly lower than those from normal controls (SMD (standard mean differences) [95% CI] -0.64 [-1.01, -0.28]). Zinc supplementation was found to significantly increase the semen volume, sperm motility and the percentage of normal sperm morphology (SMD [95% CI]: -0.99 [-1.60, -0.38], -1.82 [-2.63, -1.01], and -0.75 [-1.37, -0.14], respectively). The present study showed that the zinc level in the seminal plasma of infertile males was significantly lower than that of normal males. Zinc supplementation could significantly increase the sperm quality of infertile males. However, further studies are needed to better elucidate the correlation between seminal plasma zinc and male infertility.
Project description:To study the associations between pubertal timing and semen quality and reproductive hormones, 680 volunteers were recruited from universities in Chongqing, China. Pubertal timing was obtained using a questionnaire. The main measurements were five routine semen parameters and six reproductive hormones. After adjusting for potential confounders, we found that early pubertal timing was associated with lower sperm concentration. An one-year increase in age of peak height velocity was associated with a 4.7% (95% confidence interval [CI] = 1.0 to 8.6) increase in sperm concentration. An one-year increase in age of first spermatorrhea was associated with a 6.4% increase in sperm concentration and a 2.9% decrease in semen volume (95% CI = 1.7 to 11.3, -5.5 to -0.3; respectively). Regarding reproductive hormones, an one-year increase in age of height spurt and peak height velocity was associated with a 6.5% and a 6.7% decrease in estrogen (95% CI = -9.8 to -3.0, -10.4 to -2.8; respectively). While an one-year increase in age of height spurt was associated with higher follicle-stimulating hormone (% change = 2.6, 95% CI = 0.2 to 4.7). This was the first report that has suggested that early pubertal timing is associated with lower sperm concentration. However, further study is still needed to validate this association and fully elucidate the mechanism behind it.
Project description:Evidence concerning the association between ambient gaseous air pollutant exposures and semen quality is sparse, and findings in previous studies remain largely inconsistent. We enrolled 1759 men and performed 2184 semen examinations at a large reproductive medical center in Wuhan, China, between 2013 and 2015. Inverse distance weighting interpolation was performed to estimate individual exposures to SO2, NO2, CO, and O3 during the entire period (lag 0-90 days) and key periods (lag 0-9, 10-14, 70-90 days) of sperm development. Linear mixed models were used to analyze exposure-response relationships. SO2 exposure with 0-90 days lag was significantly associated with monotonically decreased sperm concentration (? for each interquartile range increase of exposure: -0.14; 95% CI: -0.23, -0.05), sperm count (-0.21; -0.30, -0.12) and total motile sperm count (-0.16; -0.25, -0.08). Significant associations were observed for total and progressive motility only when SO2 exposure was at the highest quintile (all Ptrend < 0.05). Similar trends were observed for SO2 exposure with 70-90 days lag. NO2, CO, or O3 exposure was not significantly associated with semen quality. Our results suggest that ambient SO2 exposure adversely affects semen quality and highlight the potential to improve semen quality by reducing ambient SO2 exposure during early stages of sperm development.
Project description:<h4>Objectives</h4>To provide information of semen quality among normal young Japanese men and indicate the frequency of reduced semen quality.<h4>Design</h4>Cross-sectional, coordinated studies of Japanese young men included from university areas. The men had to be 18-24 years, and both the man and his mother had to be born in Japan. Background information was obtained from questionnaires. Standardised and quality-controlled semen analyses were performed, reproductive hormones analysed centrally and results adjusted for confounding factors.<h4>Setting</h4>Four study centres in Japan (Kawasaki, Osaka, Kanazawa and Nagasaki).<h4>Participants</h4>1559 men, median age 21.1 years, included during 1999-2003.<h4>Outcome measures</h4>Semen volume, sperm concentration, total sperm count, sperm motility, sperm morphology and reproductive hormone levels.<h4>Results</h4>Median sperm concentration was 59 (95% CI 52 to 68) million/ml, and 9% and 31.9% had less than 15 and 40 million/ml, respectively. Median percentage of morphologically normal spermatozoa was 9.6 (8.8 to 10.3)%. Small, but statistically significant, differences were detected for both semen and reproductive hormone variables between men from the four cities. Overall, the semen values were lower than those of a reference population of 792 fertile Japanese men.<h4>Conclusions</h4>Assuming that the investigated men were representative for young Japanese men, a significant proportion of the population had suboptimal semen quality with reduced fertility potential, and as a group they had lower semen quality than fertile men. However, the definitive role-if any-of low semen quality for subfertility and low fertility rates remain to be investigated.
Project description:BACKGROUND:The available data on the significance of circulating apelin, chemerin and omentin in women with gestational diabetes mellitus (GDM) are inconsistent. This analysis includes a systematic review of the evidence associating the serum concentrations of these adipokines with GDM. METHODS:Publications through December 2019 were retrieved from PubMed, Embase, the Cochrane Library, and Web of Science. Subgroup analysis and meta-regression were conducted to evaluate sources of heterogeneity. RESULTS:Analysis of 20 studies, including 1493 GDM patients and 1488 normal pregnant women did not find significant differences in circulating apelin and chemerin levels (apelin standardized mean difference [SMD]?=?0.43, 95% confidence interval (CI): -?0.40 to 1.26, P?=?0.31; chemerin SMD?=?0.77, 95% CI -?0.07 to 1.61, P?=?0.07). Circulating omentin was significantly lower in women with GDM than in healthy controls (SMD?=?-?0.72, 95% CI -?1.26 to -?0.19, P?=?0.007). Publication bias was not found; sensitivity analysis confirmed the robustness of the pooled results. CONCLUSIONS:Circulating omentin was decreased in GDM patients, but apelin and chemerin levels were not changed. The results suggest that omentin has potential as a novel biomarker for the prediction and early diagnosis of GDM.
Project description:Emerging literature suggests that men's diets may affect spermatogenesis as reflected in semen quality indicators, but literature on the relation between meat intake and semen quality is limited. Our objective was to prospectively examine the relation between meat intake and indicators of semen quality. Men in subfertile couples presenting for evaluation at the Massachusetts General Hospital Fertility Center were invited to participate in an ongoing study of environmental factors and fertility. A total of 155 men completed a validated food-frequency questionnaire and subsequently provided 338 semen samples over an 18-mo period from 2007-2012. We used linear mixed regression models to examine the relation between meat intake and semen quality indicators (total sperm count, sperm concentration, progressive motility, morphology, and semen volume) while adjusting for potential confounders and accounting for within-person variability across repeat semen samples. Among the 155 men (median age: 36.1 y; 83% white, non-Hispanic), processed meat intake was inversely related to sperm morphology. Men in the highest quartile of processed meat intake had, on average, 1.7 percentage units (95% CI: -3.3, -0.04) fewer morphologically normal sperm than men in the lowest quartile of intake (P-trend = 0.02). Fish intake was related to higher sperm count and percentage of morphologically normal sperm. The adjusted mean total sperm count increased from 102 million (95% CI: 80, 131) in the lowest quartile to 168 million (95% CI: 136, 207) sperm in the highest quartile of fish intake (P-trend = 0.005). Similarly, the adjusted mean percentages of morphologically normal sperm for men in increasing quartiles of fish intake were 5.9 (95% CI: 5.0, 6.8), 5.3 (95% CI: 4.4, 6.3), 6.3 (95% CI: 5.2, 7.4), and 7.5 (95% CI: 6.5, 8.5) (P-trend = 0.01). Consuming fish may have a positive impact on sperm counts and morphology, particularly when consumed instead of processed red meats.