BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis

Metabolic syndrome-associated sperm alterations in an experimental rabbit model: relation with metabolic profile, testis and epididymis gene expression and effect of tamoxifen treatment

The influence of metabolic syndrome (MetS) on sperm quality and function is debated. Using a well-established high fat diet (HFD) rabbit model resembling human MetS, including development of hypogonadism, we demonstrate that HFD decreased sperm motility, morphology and acrosome reaction in response to progesterone and increased sperm cholesterol content. All the above parameters were associated with most MetS features, its severity and plasma testosterone (T) at univariate analysis. After T adjustment, sperm morphology and motility retained a significant association, respectively, with mean arterial pressure and circulating cholesterol levels. MetS modified the expression of inflammatory and tissue remodelling genes in the testis and of aquaporins in the epididymis. In a multivariate analysis, sperm morphology resulted associated with testis expression of fibronectin and collagen type 1 genes, whereas motility with epididymis aquaporin 1 gene. Administration of tamoxifen, used in the treatment of idiopathic male infertility, to HFD rabbits partially restored motility, but further decreased morphology and increased spontaneous acrosome reaction, without restoring responsiveness to progesterone. Overall our results indicate that development of MetS produces detrimental effects on sperm quality and functionality by inducing metabolic disorders leading to alterations in testis and epididymis functions and evidence a role of hypertension as a new determinant of abnormal sperm morphology, in line with a previous human study from our group.

Current smoking is associated with lower seminal vesicles and ejaculate volume, despite higher testosterone levels, in male subjects of infertile couples

STUDY QUESTION

What is the impact of smoking behaviour on seminal, hormonal and male genital tract ultrasound parameters in subjects seeking medical care for couple infertility?

STUDY ANSWER

In males of infertile couples, current smokers (CS), when compared with non-smokers, show lower ejaculate and ultrasound-derived seminal vesicles (SV) volume, despite higher testosterone levels.

WHAT IS KNOWN ALREADY

Data on the effects of smoking on male fertility are conflicting. A correlation between smoking and reduced semen parameters has been reported, however, with a high heterogeneity among studies. An association between smoking behaviour and higher testosterone levels in men has been described in several, but not all, the previous studies. No study has systematically evaluated the impact of smoking on the male genital tract ultrasound characteristics.

STUDY DESIGN, SIZE AND DURATION

Retrospective cross-sectional analysis of a consecutive series of 426 subjects seeking medical care for couple infertility from January 2010 to July 2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

From the entire cohort, 394 men (age 36.0 ± 8.0 years) free of genetic abnormalities were selected. All subjects underwent a complete andrological and physical examination, biochemical and hormonal assessment, scrotal and transrectal colour-Doppler ultrasound and semen analysis (including seminal interleukin-8 levels, sIL-8) within the same day.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the patients evaluated, 229 were never smokers (NS), 56 past smokers (PS) and 109 CS. When CS were compared with the rest of the sample (non-smokers, NS + PS), in a multivariate model (analysis of covariance, ANCOVA) adjusted for age, lifestyle (including alcohol, cannabis and physical activity), BMI and sex hormone-binding globulin, significantly higher androgen (total testosterone, P = 0.001; calculated free testosterone, P < 0.005) and lower FSH (P < 0.05) levels were observed in CS. However, when total testosterone was also included in the multivariate model as a further covariate, the difference in FSH levels was not confirmed. In a similar model, a lower ejaculate volume (P < 0.01) and a higher prevalence of normal sperm morphology (P < 0.02) were also detected in CS in comparison with the rest of the sample. However, when total testosterone was also included in the multivariate model as a further covariate, only the difference in ejaculate volume between CS and non-smokers was confirmed (-0.61 ± 0.23 ml, P < 0.01). Finally, CS showed lower total SV volume, before and after ejaculation, even after adjusting for confounders (P = 0.02 and <0.01, respectively). Similar results were observed when the reported number of cigarettes smoked or the number of pack-years was considered separately.

LIMITATIONS, REASONS FOR CAUTION

The present results are derived from patients consulting an Andrology Clinic for couple infertility, who could have different characteristics from the general male population or males consulting general practitioners for reasons other than couple infertility. In addition, we did not have a true control group composed of age-matched, apparently healthy, fertile men, and therefore true normative data of sonographic parameters cannot be inferred. Due to the cross-sectional nature of our study, neither a causality hypothesis nor mechanistic models can be drawn. Finally, this is a retrospective study, and further prospective studies are required.

WIDER IMPLICATIONS OF THE FINDINGS

We report an apparent paradox in CS: lower SV volume despite higher testosterone levels. Our data suggest that smoking may negatively affect SV volume in an independent manner, as the difference between CS and non-smokers retained significance after adjusting for confounders including testosterone. This is the first study reporting such ultrasound evidence. How this new smoking-related alteration, along with low semen volume, impacts male fertility needs to be addressed by further studies.

STUDY FUNDING/COMPETING INTERESTS

No funding was received for the study. None of the authors have any conflict of interest to declare.

Relationship between semen production and medical comorbidity

OBJECTIVE

To study the relationship between semen quality and current health status in a cohort of men evaluated for infertility.

DESIGN

Cross-sectional study.

SETTING

Fertility clinic.

PATIENT(S)

Nine thousand three hundred eighty-seven men evaluated for infertility between 1994 and 2011.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Charlson comorbidity index, medical diagnoses by organ system.

RESULT(S)

At the time of evaluation, 9,387 men with a mean age of 38 years had semen data available. Of these men, 44% had at least one medical diagnosis unrelated to infertility. When stratifying the cohort by the Charlson comorbidity index (CCI), differences in all measured semen parameters were identified. Men with a higher CCI had lower semen volume, concentration, motility, total sperm count, and morphology scores. In addition, men with diseases of the endocrine, circulatory, genitourinary, and skin diseases all showed significantly higher rates of semen abnormalities. Upon closer examination of diseases of the circulatory system, men with hypertensive disease, peripheral vascular and cerebrovascular disease, and nonischemic heart disease all displayed higher rates of semen abnormalities.

CONCLUSION(S)

The current report identified a relationship between medical comorbidites and male semen production. Although genetics help guide a man's sperm production, his current condition and health play an important role.

Metabolic syndrome and infertility in men

Metabolic syndrome is a compilation of symptoms including central obesity, insulin resistance, dyslipidemia, and hypertension. Initially used to predict cardiovascular disease, it is now clear that the molecular and physiologic abnormalities seen in metabolic syndrome extend well beyond the cardiovascular system. Growing evidence has linked metabolic syndrome and its individual symptoms to the increasing prevalence of male infertility. This manuscript reviews the recent evidence connecting metabolic syndrome to male infertility as well as the underlying pathophysiology. Currently, there are limited prospective studies examining the effects of treating metabolic syndrome on male reproduction and these relationships will need to be a focus of further investigation.

Proteomic pattern changes associated with obesity-induced asthenozoospermia

Obesity, an increasingly frequent societal disease can also be accompanied by declines in spermatozoa quality and male subfecundity. To determine if there are obesity-associated proteomic changes potentially affecting sperm quality and motility, differential proteomic analysis was performed on spermatozoa from both obesity-associated asthenozoospermia and clinically healthy individuals, using a label-free quantitative LC-MS/MS approach. We resolved 1975 proteins in the human sperm proteome, amongst which, 105 proteins were less abundant, whereas 22 other proteins increased in obesity-associated asthenozoospermia. Functional category analyses indicated that the differentially expressed proteins are mainly related to cytoskeletal regulation, vesicle biogenesis, metabolism, and protein degradation involved in spermiogenesis and sperm motility. Furthermore, declines in endoplasmic reticulum protein 57 (ERp57) and actin-binding-related protein T2 (ACTRT2) expression were verified by immunofluorescence, Western blot, and flow cytometry analyses. It is evident that ERp57 is localized in the acrosome region, neck and principal piece of human spermatozoa, whereas ACTRT2 is localized in the post-acrosomal region and middle piece. Thus, these differences in protein expression in asthenozoospermia may contribute to the underlying sperm quality defects afflicting these individuals. Notably, declines in ERp57 and ACTRT2 expression in obesity-associated asthenozoospermia may play critical roles in reducing sperm motility.

Acrosome reaction is impaired in spermatozoa of obese men: a preliminary study

OBJECTIVE

To compare spontaneous (Sp-AR) and P-induced acrosome reaction (AR) in spermatozoa of obese and lean subjects.

SETTING

Bariatric unit at a university hospital.

DESIGN

Prospective, observational study.

PATIENT(S)

Twenty-three obese (mean±SD body mass index [BMI], 44.3±5.9 kg/m2) and 25 age-matched lean (BMI, 24.2±3.0 kg/m2) subjects.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Spontaneous and P-induced AR in spermatozoa of obese and lean subjects.

RESULT(S)

A statistically significant difference was found between obese and lean cohorts in total T and calculated free T, E2, glycated hemoglobin, and high-density lipoproteins, whereas among the routine semen parameters analyzed, only immotile sperm percentage and ejaculate volume differed significantly. Spermatozoa of obese (n=13) vs. lean men (n=19) showed a higher Sp-AR (17.9%±7.2% vs. 8.3%±4.2%), which resulted in a reduced ability to respond to P evaluated as the AR-after-P-challenge parameter (3.5%±3.2% vs. 17.6%±9.2%). Multivariate analysis adjusted for age revealed a significant correlation between BMI, waist, E2, and glycated hemoglobin with both Sp-AR (age-adjusted r=0.654, r=0.711, r=0.369, and r=0.644, respectively) and AR-after-P-challenge (age-adjusted r=-0.570, r=-0.635, r=-0.507, and r=-0.563, respectively). A significant difference in sperm cholesterol content was reported between obese and lean men (29.8±19.5 vs. 19.1±14.6 ng/μg of proteins).

CONCLUSION(S)

Sperm AR is impaired in obese men, showing reduced response to P and elevated Sp-AR, associated with altered circulating levels of E2 and sperm cholesterol content.

High body mass index has a deleterious effect on semen parameters except morphology: results from a large cohort study

OBJECTIVE

To evaluate the influence of body mass index (BMI) on semen characteristics.

DESIGN

Cohort study.

SETTING

Single private andrology laboratory.

PATIENT(S)

All patients (n=10,665) consulting for a semen analysis from October 9, 2010, to October 8, 2011. When analyses were repeated on the same patient, only the first was included.

INTERVENTION(S)

Recording of self-reported weight and height and of semen analysis.

MAIN OUTCOME MEASURE(S)

All parameters of standard semen analysis: pH, volume, sperm concentration per mL, total sperm count per ejaculate, motility (%) within 1 hour after ejaculation (overall and progressive), viability (%), and normal sperm morphology (%). Parametric and nonparametric statistical methods were applied, and results are given either with mean±SD, or 10th, 50th, and 90th percentiles.

RESULT(S)

Semen volume decreased from 3.3±1.6 to 2.7±1.6 mL when BMI increased from normal (20-25 kg/m2) to extreme obesity (>40 kg/m2). The same was true for semen concentration (56.4±54.9 to 39.4±51.0 million/mL), total sperm count (171±170 to 92±95 million), and progressive motility (36.9±16.8% to 34.7±17.1%). The percentage of cases with azoospermia and cryptozoospermia increased from 1.9% to 9.1% and from 4.7% to 15.2%, respectively. The other semen characteristics were not affected. Multivariate models including age and abstinence duration confirmed these results.

CONCLUSION(S)

In this study, on a large patient sample size, increased BMI was associated with decreased semen quality, affecting volume, concentration, and motility. The percentage of normal forms was not decreased.

In utero exposure to persistent organochlorine pollutants and reproductive health in the human male

Persistent organochlorine pollutants (POPs) are ubiquitous, bioaccumulative compounds with potential endocrine-disrupting effects. They cross the placental barrier thereby resulting in in utero exposure of the developing fetus. The objective of this study was to investigate whether maternal serum concentrations of polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) during pregnancy are associated with son's semen quality and reproductive hormone levels. During 2008-2009, we recruited 176 male offspring from a Danish cohort of pregnant women who participated in a study in 1988-1989. Each provided semen and blood samples that were analyzed for sperm concentration, total sperm count, motility, and morphology, and reproductive hormone levels, respectively. The maternal blood samples were collected in pregnancy week 30 and were analyzed for the concentrations of six PCBs (PCB-118, -138, -153, -156, -170, and -180) and p,p'-DDE. The potential associations between in utero exposure to ΣPCBs (pmol/ml), Σdioxin like-(DL) PCBs (PCB-118 and -156) (pmol/ml), and p,p'-DDE and semen quality and reproductive hormone levels were investigated using multiple regression. Maternal median (range) exposure levels of ΣPCB, ΣDL-PCB, and p,p'-DDE were 10.0 (2.1-35.0) pmol/ml, 0.8 (0.2-2.7) pmol/ml, and 8.0 (0.7-55.3) pmol/ml, respectively, reflecting typical background exposure levels in the late 1980s in Denmark. Results suggested that in utero exposure to ΣPCB, ΣDL-PCB, and p,p'-DDE was not statistically significantly associated with semen quality measures or reproductive hormone levels. Thus, results based on maternal PCB and p,p'-DDE concentrations alone are not indicative of long-term consequences for male reproductive health; however, we cannot exclude that these POPs in concert with other endocrine-modulating compounds may have adverse effects.

Epidemiologic methods for investigating male fecundity

Fertility is a couple concept that has been measured since the beginning of demography, and male fecundity (his biological capacity to reproduce) is a component of the fertility rate. Unfortunately, we have no way of measuring the male component directly, although several indirect markers can be used. Population registers can be used to monitor the proportion of childless couples, couples who receive donor semen, trends in dizygotic twinning, and infertility diagnoses. Studies using time-to-pregnancy (TTP) may identify couple subfecundity, and TTP data will correlate with sperm quality and quantity as well as sexual activity and a number of other conditions. Having exposure data available for couples with a fecund female partner would make TTP studies of interest in identifying exposures that may affect male fecundity. Biological indicators such as sperm quality and quantity isolate the male component of fertility, and semen data therefore remain an important source of information for research. Unfortunately, often over half of those invited to provide a sperm sample will refuse, and the study is then subject to a selection that may introduce bias. Because the most important time windows for exposures that impair semen production could be early fetal life, puberty, and the time of ejaculation; longitudinal data over decades of time are required. The ongoing monitoring of semen quality and quantity should continue, and surveys monitoring fertility and waiting TTP should also be designed.

Obesity independently influences gonadal function in very long-term adult male survivors of childhood cancer

OBJECTIVE

Although obesity is associated with gonadal dysfunction in the general population, gonadotoxic treatment might diminish the impact of obesity in childhood cancer survivors (CCS). The aim was to evaluate whether altered body composition is associated with gonadal dysfunction in male CCS, independent of gonadotoxic cancer treatment.

METHODS

Three hundred fifty-one male CCS were included. Median age at diagnosis was 5.9 years (0-17.8) and median age at follow-up 25.6 years (18.0-45.8). Total and non-SHBG-bound testosterone, sex hormone-binding globulin, inhibin B, and follicle-stimulating hormone (FSH) were studied. Potential determinants were BMI, waist circumference, waist-hip ratio, and body composition measures (dual energy X-ray absorptiometry).

RESULTS

Non-SHBG-bound testosterone was significantly decreased in survivors with BMI ≥ 30 kg/m(2) (adjusted mean 9.1 nmol/L vs. 10.2 nmol/L, P = 0.015), high fat percentage (10.0 vs. 11.2, P = 0.004), and high waist circumference (>102 cm) (9.0 vs. 11.0, P = 0.020). Survivors with high fat percentage (≥25%) had significantly lower inhibin B/FSH ratios (inhibin B/FSH ratio: β -34%, P = 0.041).

CONCLUSION

Obesity is associated with gonadal dysfunction in male CCS, independent of the irreversible effect of previous cancer treatment. Randomized controlled trials are required to evaluate whether weight normalization could improve gonadal function, especially in obese survivors with potential other mechanisms than lifestyle causing their obesity.

Physical activity is not related to semen quality in young healthy men

OBJECTIVE

To study the relationship of physical activity with semen quality among healthy young men from Spain.

DESIGN

Cross-sectional study.

SETTING

University and college campuses of Murcia Region, Spain.

PATIENT(S)

Healthy young men with untested fertility (n = 215).

INTERVENTION(S)

A physical examination, blood and semen samples, and completion of a questionnaire.

MAIN OUTCOME MEASURE(S)

Semen quality parameters.

RESULT(S)

Physical activity was not related to semen quality parameters. The adjusted percentage differences (95% confidence interval) in semen parameters comparing men in the top quartile of moderate-to-vigorous physical activity (≥9.5 h/wk) with men in the bottom quartile (≤3 h/wk) were 4.3% (-30.2%, 38.9%) for total sperm count, 7.2% (-30.6%, 45.1%) for sperm concentration, -2.42% (-6.53%, 1.69%) for sperm motility, and 12.6% (-12.0%, 37.2%) for sperm morphology.

CONCLUSION(S)

In contrast to previous research among athletes, these data suggest that physical activity is not deleterious to testicular function, as captured by semen quality parameters in this population of healthy young men in Spain.

CREM variants rs4934540 and rs2295415 conferred susceptibility to nonobstructive azoospermia risk in the Chinese population

To evaluate the association of variants related to spermatogenesis with susceptibility to Chinese idiopathic nonobstructive azoospermia (NOA), seventeen tag single-nucleotide polymorphisms (SNPs) in CREM, ACT, KIF17b, and SPAG8 were analyzed in 361 NOA patients and 368 controls by Sequenom iplex technology. The results showed that two CREM SNPs, rs4934540 and rs22954152, were significantly associated with NOA and played protective roles against the disease (P value with Bonferroni correction = 0.00017, odds ratio [OR] = 0.624 and P = 0.012, OR = 0.686, respectively). Haplotype analysis of CREM gene variants suggested that haplotype CGTG of the SNPs, rs4934540, rs2295415, rs11592356, and rs1148247, exhibited significant protective effect against the occurrence of NOA (P = 0.001, OR = 0.659). The haplotype TATG conferred a significantly increased risk of NOA (P = 0.011, OR = 1.317). Furthermore, making use of quantitative RT-PCR, we demonstrated that relative mRNA expression of CREM in NOA patients with maturation arrest was only one-third of that in the controls with normal spermatogenesis (P < 0.0001). Our findings indicated that the polymorphisms of CREM gene were associated with NOA in the Chinese population and low CREM expression might be involved in the pathogenesis of spermatogenesis maturation arrest.

Alcohol and male reproductive health: a cross-sectional study of 8344 healthy men from Europe and the USA

STUDY QUESTION

Is there an association between alcohol intake and semen quality and serum reproductive hormones among healthy men from the USA and Europe?

SUMMARY ANSWER

Moderate alcohol intake is not adversely associated with semen quality in healthy men, whereas it was associated with higher serum testosterone levels.

WHAT IS KNOWN ALREADY

High alcohol intake has been associated with a wide range of diseases. However, few studies have examined the correlation between alcohol and reproductive function and most have been conducted in selected populations of infertile men or have a small sample size and the results have been contradictory.

STUDY DESIGN, SIZE, DURATION

A coordinated international cross-sectional study among 8344 healthy men. A total of 1872 fertile men aged 18-45 years (with pregnant partners) from four European cities and four US states, and 6472 young men (most with unknown fertility) aged 18-28 years from the general population in six European countries were recruited.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The men were recruited using standardized protocols. A semen analysis was performed and men completed a questionnaire on health and lifestyle, including their intake of beer, wine and liquor during the week prior to their visit. Semen quality (semen volume, sperm concentration, percentage motile and morphologically normal sperm) and serum reproductive hormones (FSH, LH, testosterone, sex hormone-binding globulin, and inhibin B and free testosterone) were examined.

MAIN RESULTS AND THE ROLE OF CHANCE

The participation rate for our populations was 20-30%. We found no consistent association between any semen variable and alcohol consumption, which was low/moderate in this group (median weekly intake 8 units), either for total consumption or consumption by type of alcohol. However, we found a linear association between total alcohol consumption and total or free testosterone in both groups of men. Young and fertile men who consumed >20 units of alcohol per week had, respectively, 24.6 pmol/l (95% confidence interval 16.3-32.9) and 19.7 pmol/l (7.1-32.2) higher free testosterone than men with a weekly intake between 1 and 10 units. Alcohol intake was not significantly associated with serum inhibin B, FSH or LH levels in either group of men. The study is the largest of its kind and has sufficient power to detect changes in semen quality and reproductive hormones.

LIMITATIONS, REASONS FOR CAUTION

The participation rate was low, but higher than in most previous semen quality studies. In addition, the study was cross-sectional and the men were asked to recall their alcohol intake in the previous week, which was used as a marker of intake up to 3 months before. If consumption in that week differed from the typical weekly intake and the intake 3 months earlier, misclassification of exposure may have occurred. However, the men were unaware of their semen quality when they responded to the questions about alcohol intake. Furthermore, we cannot exclude that our findings are due to unmeasured confounders, including diet, exercise, stress, occupation and risk-taking behavior.

WIDER IMPLICATIONS OF THE FINDINGS

Our study suggests that moderate alcohol intake is not adversely associated with semen quality in healthy men, whereas it was associated with higher serum testosterone levels which may be due to a changed metabolism of testosterone in the liver. Healthy men may therefore be advised that occasional moderate alcohol intake may not harm their reproductive health; we cannot address the risk of high alcohol consumption of longer duration or binge drinking on semen quality and male reproductive hormones.

STUDY FUNDING/COMPETING INTERESTS

All funding sources were non-profitable and sponsors of this study played no role in the study design, in data collection, analysis, or interpretation, or in the writing of the article. The authors have no conflicts of interest.

Semen quality, infertility and mortality in the USA

STUDY QUESTION

What is the relationship between semen parameters and mortality in men evaluated for infertility?

SUMMARY ANSWER

Among men undergoing an infertility evaluation, those with abnormal semen parameters have a higher risk of death, suggesting a possible common etiology between infertility and mortality.

WHAT IS KNOWN ALREADY

Conflicting data exist that suggest either an inverse relationship or no relationship between semen quality and mortality.

STUDY DESIGN, SIZE, DURATION

A study cohort was identified from two centers, each specializing in infertility care. In California, we identified men with data from 1994 to 2011 in the Stanford Reproductive Endocrinology and Infertility semen database. In Texas, we identified men with data from 1989 to 2009 contained in the andrology database at the Baylor College of Medicine Special Procedures Laboratory who were evaluated for infertility. Mortality was determined by data linkage to the National Death Index or Social Security Death Index. Comorbidity was estimated based on calculation of the Charlson Comorbidity Index or Centers for Medicare & Medicaid Services-Hierarchical Condition Categories Model.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In all, 11,935 men were evaluated for infertility from 1989 to 2011. During 92 104 person years of follow-up, 69 of 11,935 men died (0.58%). The mean age at infertility evaluation was 36.6 years with a mean follow-up of 7.7 years.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with the general population, men evaluated for infertility had a lower risk of death with 69 deaths observed compared with 176.7 expected (Standardized mortality rate 0.39, 95% CI 0.30-0.49). When stratified by semen parameters, however, men with impaired semen parameters (i.e. male factor infertility) had significantly higher mortality rates compared with men with normal parameters (i.e. no male factor infertility). Low semen volume, sperm concentration, sperm motility, total sperm count and total motile sperm count were all associated with higher risk of death. In contrast, abnormal sperm morphology was not associated with mortality. While adjusting for current health status attenuated the association between semen parameters and mortality, men with two or more abnormal semen parameters still had a 2.3-fold higher risk of death compared with men with normal semen (95% CI 1.12-4.65).

LIMITATIONS, REASONS FOR CAUTION

Our cohort represents infertile men, which may limit generalizability. As comorbidity relied on administrative data, granular information on each man regarding infertility diagnosis and lifestyle factors was unavailable.

WIDER IMPLICATIONS OF THE FINDINGS

Men with impaired semen parameters have an increased mortality rate in the years following an infertility evaluation suggesting semen quality may provide a marker of health.

STUDY FUNDING/COMPETING INTEREST(S)

This study is supported in part by P01HD36289 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health (to D.J.L. and L.I.L.). The project was also partially supported by an NIH CTSA award number UL1 RR025744. None of the authors has any conflict of interest to declare.

Sugar-sweetened beverage intake in relation to semen quality and reproductive hormone levels in young men

STUDY QUESTION

Is consumption of sugar-sweetened beverages (SSB) associated with semen quality?

SUMMARY ANSWER

Higher consumption of SSB was associated with lower sperm motility among healthy, young men.

WHAT IS KNOWN ALREADY

The existing literature on the potential role of SSBs on male reproductive function is scarce and primarily focused on the relation between caffeinated beverages and semen quality. However, a rodent model suggests that SSBs may hamper male fertility.

STUDY DESIGN, SIZE, DURATION

The Rochester Young Men's Study; a cross-sectional study of 189 healthy young men carried out at the University of Rochester during 2009-2010.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men aged 18-22 years provided semen and blood samples, underwent a physical examination and completed a previously validated food frequency questionnaire (FFQ). Linear regression was used to analyze the association of SSBs with sperm parameters and reproductive hormone levels while adjusting for potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

SSB intake was inversely related to progressive sperm motility. Men in the highest quartile of SSB intake (≥1.3 serving/day) had 9.8 (95% CI: 1.9,17.8) percentage units lower progressive sperm motility than men in the lowest quartile of intake (<0.2 serving/day) (P, trend = 0.03). This association was stronger among lean men (P, trend = 0.005) but absent among overweight or obese men (P, trend = 0.98). SSB intake was unrelated to other semen quality parameters or reproductive hormones levels.

LIMITATIONS, REASONS FOR CAUTION

As in all cross-sectional studies, causal inference is limited. An additional problem is that only single semen sample was obtained from each subject.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first report on the relation between SSB intake and low semen quality beyond the contribution of caffeinated beverages. While our findings are in agreement with recent experimental data in rodents, more studies are required to draw conclusions on the relation of SSB with semen quality or male infertility.

STUDY FUNDING/COMPETING INTEREST(S)

Supported by the European Union Seventh Framework Program (Environment), 'Developmental Effects of Environment on Reproductive Health' (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 and T32HD060454 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

Obesity is associated with increased seminal insulin and leptin alongside reduced fertility parameters in a controlled male cohort

BACKGROUND

Obesity appears to be associated with male reproductive dysfunction and infertility, although this has been inconsistent and inconclusive. Insulin and leptin are known mediators and modulators of the hypothalamus-pituitary-testes axis, contributing to the regulation of male reproductive potential and overall wellbeing. These hormones are also present in semen influencing sperm functions. Although abdominal obesity is closely associated with insulin resistance (hyperinsulinaemia), hyperleptinaemia and glucose dysfunction, changes in seminal plasma concentrations of insulin, leptin and glucose in obese males has not previously been investigated.

METHODS

This small case controlled study assessed serum and seminal concentrations of insulin, leptin and glucose in obese (BMI > =30; n = 23) and non-obese (BMI < 30; n = 19) males. Following a detailed medical history and examination, participants meeting the inclusion criteria were entered for data analysis. Body parameters such as BMI, waist and hip circumference and the waist hip ratio were measured. Serum and semen samples were collected and assayed for insulin, leptin and glucose. Semen samples also underwent a standard semen analysis, with sperm mitochondrial membrane potential (MMP) and DNA fragmentation (DF).

RESULTS

Obesity was associated with increased serum and seminal insulin and leptin, with no significant difference in seminal glucose. Serum and seminal concentrations of insulin and leptin were positively correlated. Furthermore, obesity was associated with decreased sperm concentration, sperm vitality and increased MMP and DF, with a non-significant impact on motility and morphology.

CONCLUSIONS

Hyperinsulinaemia and hyperleptinaemia are associated with increased seminal insulin and leptin concentrations, which may negatively impact male reproductive function in obesity. Insulin was also found to be highly concentrated in the seminal plasma of both groups. This data will contribute to the contradictive information available in the literature on the impact of obesity and male reproduction.

Basic diagnostics in andrology

Basic andrological diagnosis consists of taking the patient's medical history and the couple's history as well as performing a physical examination including genital ultrasound, spermiogram, and hormonal analysis. If needed, a testicular biopsy and genetic testing may also be performed. Recent studies have shown the effect of lifestyle factors on male fertility. Thus, the patient history and clinical/andrological examinations have been broadened to include information on metabolic disorders like obesity and diabetes mellitus. The biggest changes occurred with the publication of the fifth edition of the WHO laboratory manual in 2010 and the introduction of a section on semen analysis in the German Medical Association guidelines (RiliBÄK). The reference values for almost all spermiogram parameters were adapted in an evidence-based approach using worldwide prospective population studies. For central parameters such as sperm motility and morphology, the assessment criteria were changed. New independent markers such as sperm DNA fragmentation rate are now routinely used in clinical diagnosis. For German andrological laboratories, there are now mandatory quality assurance measures for semen analysis (in the German "Rili-BÄK" guidelines). These include duplicate testing of all standard semen parameters and inter-laboratory comparison at regular intervals.

Lack of testicular seipin causes teratozoospermia syndrome in men

Obesity impairs male fertility, providing evidence for a link between adipose tissue and reproductive function; however, potential consequences of adipose tissue paucity on fertility remain unknown. Lack of s.c. fat is a hallmark of Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2), which is caused by mutations in BSCL2-encoding seipin. Mice with a targeted deletion of murine seipin model BSCL2 with severe lipodystrophy, insulin resistance, and fatty liver but also exhibit male sterility. Here, we report teratozoospermia syndrome in a lipodystrophic patient with compound BSCL2 mutations, with sperm defects resembling the defects of infertile seipin null mutant mice. Analysis of conditional mouse mutants revealed that adipocyte-specific loss of seipin causes progressive lipodystrophy without affecting fertility, whereas loss of seipin in germ cells results in complete male infertility and teratozoospermia. Spermatids of the human patient and mice devoid of seipin in germ cells are morphologically abnormal with large ectopic lipid droplets and aggregate in dysfunctional clusters. Elevated levels of phosphatidic acid accompanied with an altered ratio of polyunsaturated to monounsaturated and saturated fatty acids in mutant mouse testes indicate impaired phospholipid homeostasis during spermiogenesis. We conclude that testicular but not adipose tissue-derived seipin is essential for male fertility by modulating testicular phospholipid homeostasis.

Percentage change of FSH value: new variable to predict the seminal outcome after varicocelectomy

In the literature, there is no good agreement with variables to predict seminal outcome after varicocelectomy. The purpose of this study was to evaluate the FSH percentage change (Δ% FSH) as a predictor of the seminal outcome after varicocelectomy together with other known predictors. We evaluated 118 patients who underwent varicocelectomy. We assessed factors that could be predictors of the improvement of semen characteristics: LH, FSH, total and free testosterone before operation, testis volume, age, testicular pain, body mass index (BMI), Δ% FSH, varicocele Doppler ultrasound grade using regression analysis. Mean sperm concentration increased from 27 ± 12 to 52 ± 15 million per ml post-operatively (P < 0.003), mean sperm motility increased from 31 ± 12 to 40 ± 13 million per ml following the operation (P < 0.02), also mean FSH value changed from 10.2 ± 8.3 to 6.7 ± 7.2 UI/L (P < 0.01). In unvaried regression analysis, Δ% FSH, BMI and age were predictors of the improvement of semen characteristics. In multiple regression analysis, only Δ% FSH and age were predictors. Negative correlation with age and positive correlation with Δ% FSH were observed. Our findings suggest that Δ% FSH (before and after varicocelectomy) and age are significant factors predicting the improvement of semen characteristics.

Metabolic syndrome and prostate abnormalities in male subjects of infertile couples

No previous study has evaluated systematically the relationship between metabolic syndrome (MetS) and prostate-related symptoms and signs in young infertile men. We studied 171 (36.5 ± 8.3-years-old) males of infertile couples. MetS was defined based on the National Cholesterol Education Program Third Adult Treatment Panel. All men underwent hormonal (including total testosterone (TT) and insulin), seminal (including interleukin-8 (IL-8), seminal plasma IL-8 (sIL-8)), scrotal and transrectal ultrasound evaluations. Because we have previously assessed correlations between MetS and scrotal parameters in a larger cohort of infertile men, here, we focused on transrectal features. Prostate-related symptoms were assessed using the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) and the International Prostate Symptom Score (IPSS). Twenty-two subjects fulfilled MetS criteria. In an age-adjusted logistic ordinal model, insulin levels increased as a function of MetS components (Wald = 29.5, P < 0.0001) and showed an inverse correlation with TT (adjusted r = -0.359, P< 0.0001). No association between MetS and NIH-CPSI or IPSS scores was observed. In an age-, TT-, insulin-adjusted logistic ordinal model, an increase in number of MetS components correlated negatively with normal sperm morphology (Wald = 5.59, P< 0.02) and positively with sIL-8 levels (Wald = 4.32, P < 0.05), which is a marker of prostate inflammation, with prostate total and transitional zone volume assessed using ultrasound (Wald = 17.6 and 12.5, both P < 0.0001), with arterial peak systolic velocity (Wald = 9.57, P = 0.002), with texture nonhomogeneity (hazard ratio (HR) = 1.87 (1.05-3.33), P < 0.05), with calcification size (Wald = 3.11, P< 0.05), but not with parameters of seminal vesicle size or function. In conclusion, in males of infertile couples, MetS is positively associated with prostate enlargement, biochemical (sIL8) and ultrasound-derived signs of prostate inflammation but not with prostate-related symptoms, which suggests that MetS is a trigger for a subclinical, early-onset form of benign prostatic hyperplasia.

In subfertile couple, abdominal fat loss in men is associated with improvement of sperm quality and pregnancy: a case-series

Background

The impact of overweight among men of reproductive-age may affect fertility. Abdominal fat, more than body mass index, is an indicator of higher metabolic risk, which seems to be involved in decreasing sperm quality.

This study aims to assess the relationship between abdominal fat and sperm DNA fragmentation and the effect of abdominal fat loss, among 6 men in subfertile couples.

Methods

Sperm DNA fragmentation, abdominal fat and metabolic and hormonal profiles were measured in the 6 men before and after dietary advices. Seminal oxidative stress and antioxidant markers were determined.

Results

After several months of a lifestyle program, all 6 men lost abdominal fat (patient 1: loss of 3 points of abdominal fat, patient 2: loss of 3 points, patient 3: loss of 2 points, patient 4: loss of 1 point, patient 5: loss of 4 points and patient 6: loss of 13 points). At the same time, their rate of sperm DNA fragmentation decreased: 9.5% vs 31%, 24% vs 43%, 18% vs 47%, 26.3% vs 66%, 25.4% vs 35% and 1.7% vs 25%. Also, an improvement in both metabolic (significant decrease in triglycerides and total cholesterol; p = 0.0139) and hormonal (significant increase in testosterone/oestradiol ratio; p = 0.0139) blood profiles was observed after following the lifestyle program. In seminal plasma, the amount of SOD2 has significantly increased (p = 0.0139) while in parallel carbonylated proteins have decreased. Furthermore, all spouses got pregnant. All pregnancies were brought to term.

Conclusion

This study shows specifically that sperm DNA fragmentation among men in subfertile couples could be affected by abdominal fat, but improvement of lifestyle factor may correct this alteration. The effect of specific abdominal fat loss on sperm quality needs further investigation. The reduction of oxidative stress may be a contributing factor.

Age, the environment and our reproductive future: bonking baby boomers and the future of sex

There has never been a greater need for scientists trained in reproductive science. Most developed countries are witnessing unprecedented rates of recourse to assisted conception sitting cheek-by-jowl with high rates of induced abortion. This article addresses these two incongruous faces of reproductive healthcare. Every year at least 44 million abortions are performed worldwide, many under unsafe and insanitary conditions that carry a significant risk to the lives of women deprived of safe, effective methods for controlling their fertility. Although birth control is a complex issue involving myriad social and political factors, the technical vacuum in this area is significant. Through no fault of the family planning authorities, there have been no radically new methods of fertility control since the oral contraceptive pill was introduced in 1960 and even this contribution to planned parenthood has its roots in the biochemistry of the 1920s and 1930s. Moreover, the pharmaceutical industry has, by and large, turned its back on fundamental research activities in this area. At present, our major investment in reproductive healthcare involves treating ever-increasing numbers of couples with assisted reproductive technologies (ART). However, these treatments are often delivered without critically considering the underlying causes of this condition or seriously contemplating the long-term consequences of the current enthusiasm for such therapy. Significantly, the clinical factors underpinning the commitment of couples to ART include advanced maternal age and a variety of lifestyle factors, such as smoking and obesity, which are known to compromise the developmental potential of the oocyte and DNA integrity in spermatozoa.

The relationship between male BMI and waist circumference on semen quality: data from the LIFE study

STUDY QUESTION

What is the relationship between body size, physical activity and semen parameters among male partners of couples attempting to become pregnant?

SUMMARY ANSWER

Overweight and obesity are associated with a higher prevalence of low ejaculate volume, sperm concentration and total sperm count.

WHAT IS KNOWN ALREADY

Higher BMI is associated with impaired semen parameters, while increasing waist circumference (WC) is also associated with impaired semen parameters in infertile men.

STUDY DESIGN, SIZE, DURATION

Data from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study were utilized. The LIFE study is a population-based prospective cohort of 501 couples attempting to conceive in two geographic areas (Texas and Michigan, USA) recruited in 2005-2009. Couples were recruited from four counties in Michigan and 12 counties in Texas to ensure a range of environmental exposures and lifestyle characteristics. In person interviews were conducted to ascertain demographic, health and reproductive histories followed by anthropometric assessment.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We categorized BMI (kg/m(2)) as <25.0 (underweight and normal), 25.0-29.9 (overweight) 30.0-34.9 (obese, class I) and ≥35 (obese, class II) for analysis. Data were available for analysis in 468 men (93% participation), with a mean ± SD age of 31.8 ± 4.8 years, BMI of 29.8 ± 5.6 kg/m(2) and WC of 100.8 ± 14.2 cm. The majority of the cohort (82%) was overweight or obese with 58% reporting physical activity <1 time/week. The median sperm concentration for the men in the cohort was 60.2 M/ml with 8.6% having oligospermia (<15 M/ml).

MAIN RESULTS AND THE ROLE OF CHANCE

When examining semen parameters, ejaculate volume showed a linear decline with increasing BMI and WC (P < 0.01). Similarly, the total sperm count showed a negative linear association with WC (P < 0.01). No significant relationship was seen between body size (i.e. BMI or WC) and semen concentration, motility, vitality, morphology or DNA fragmentation index. The percentage of men with abnormal volume, concentration and total sperm increased with increasing body size (P < 0.05). No relationship between physical activity and semen parameters was identified.

LIMITATIONS, REASONS FOR CAUTION

Our cohort was largely overweight and sedentary, which may result in limited external validity, i.e. generalizability. The lack of physical activity did preclude examination of exercise more frequently than once per week, thus our ability to examine more active individuals is limited.

WIDER IMPLICATIONS OF THE FINDINGS

Body size (as measured by BMI or WC) is negatively associated with semen parameters with little influence of physical activity. Our findings are the first showing a relationship between WC and semen parameters in a sample of men without known infertility. Given the worldwide obesity epidemic, further study of the role of weight loss to improve semen parameters is warranted.

STUDY FUNDING/COMPETING INTEREST(S)

Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (Contracts #N01-HD-3-3355, N01-HD-3-3356 and N01-HD-3-3358). There are no competing interests.

The epidemiology of male infertility

The purpose of this review is to integrate understanding of epidemiology and infertility. A primer on epidemiologic science and an example disease for which the design of epidemiologic investigations is readily apparent are provided. Key features of infertility that limit epidemiologic investigation are described and a survey of available data on the epidemiology of infertility provided. Finally, the work that must be completed to move this area of research forward is proposed, and, with this new perspective of "infertility as a disease," improvements envisioned in public health that may be gained through improved understanding of the epidemiology of male infertility.

Weight loss and melatonin reduce obesity-induced oxidative damage in rat testis

Aim. We aimed to evaluate the antioxidant effects of weight loss and melatonin on the obesity-induced oxidative damage in rat testes. Materials and Methods. 28 male Wistar albino rats were randomly divided into 4 groups, each consisting of 7 rats: control group (Group 1), obesity group (Group 2), obesity + MLT group (Group 3), and weight loss group (Group 4). Rats were weighed at the beginning and at the end of the study. Bilateral orchiectomy was performed and 5 cc blood samples were obtained from all of the rats. Superoxide dismutase (SOD), malondialdehyde (MDA), and protein carbonyl (PC) levels were analysed in the testicular tissues and serum. Spermatogenesis was evaluated with the Johnsen scoring system. Results. The testicular tissue and serum levels of MDA, PC, and SOD activity were increased in the obesity group in comparison to the sham operated group (P < 0.05). Weight loss and melatonin treatment ameliorated MDA, PC, and SOD levels in testicular tissue and serum significantly (P < 0.05). There was no significant difference between groups in terms of mean Johnsen score (P = 0.727). Conclusion. Experimentally created obesity caused oxidative stress and both melatonin and weight loss reduced oxidative stress parameters in rat testes.

Obesity leads to higher risk of sperm DNA damage in infertile patients

There has been a growing interest over the past few years in the impact of male nutrition on fertility. Infertility has been linked to male overweight or obesity, and conventional semen parameter values seem to be altered in case of high body mass index (BMI). A few studies assessing the impact of BMI on sperm DNA integrity have been published, but they did not lead to a strong consensus. Our objective was to explore further the relationship between sperm DNA integrity and BMI, through a 3-year multicentre study. Three hundred and thirty male partners in subfertile couples were included. Using the terminal uridine nick-end labelling (TUNEL) assay, we observed an increased rate of sperm DNA damage in obese men (odds ratio (95% confidence interval): 2.5 (1.2-5.1)).