title: Alcohol and male reproductive health: a cross-sectional study of 8344 healthy men from Europe and the USA.
abstract: OBJECTIVE
  Is there an association between alcohol intake and semen quality and serum reproductive hormones among healthy men from the USA and Europe?
  
  
  CONCLUSIONS
  Moderate alcohol intake is not adversely associated with semen quality in healthy men, whereas it was associated with higher serum testosterone levels.
  
  
  BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  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.
authors.affiliation: Department of Environmental Epidemiology, University of Southern Denmark, Winsløwsparken 17, Odense, Denmark Department of Growth and Reproduction, Rigshospitalet, Blegdamsvej 9, Copenhagen, Denmark tkjensen@health.sdu.dk.
authors.forename: Tina Kold
authors.initials: TK
authors.lastname: Jensen
authors.affiliation: Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Shanna
authors.initials: S
authors.lastname: Swan
authors.affiliation: University Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Jørgensen
authors.affiliation: Physiology, University of Turku, Turku, Finland.
authors.forename: Jorma
authors.initials: J
authors.lastname: Toppari
authors.affiliation: Department of Medicine and Urologic Surgery, University Of Minnesota, Minneapolis, MN, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Redmon
authors.affiliation: Department of Andrology Unit, Tartu University Clinicum, Tartu, Estonia.
authors.forename: Margus
authors.initials: M
authors.lastname: Punab
authors.affiliation: Department of Obstetrics, Gynecology and Women's Health, School of Medicine, University of Missouri, Columbia, MO, USA.
authors.forename: Erma Z
authors.initials: EZ
authors.lastname: Drobnis
authors.affiliation: Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Oslo, Norway.
authors.forename: Trine Berit
authors.initials: TB
authors.lastname: Haugen
authors.affiliation: Institute of Endocrinology, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Birute
authors.initials: B
authors.lastname: Zilaitiene
authors.affiliation: Department of Obstetrics & Gynecology, University of Iowa, Iowa City, IA, USA.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Sparks
authors.affiliation: Medical Directorate, NHS Education for Scotland, Edinburgh, UK Simpson Centre for Reproductive Health, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: D Stewart
authors.initials: DS
authors.lastname: Irvine
authors.affiliation: Clinical and Translational Research Center, Harbor-UCLA Medical Center, Torrance, CA, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Wang
authors.affiliation: Biologie de la Reproduction, Hopital Cochin - Universite Paris V, Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Jouannet
authors.affiliation: Department of Obstetrics and Gynecology, University of California, Davis, CA, USA.
authors.forename: Charlene
authors.initials: C
authors.lastname: Brazil
authors.affiliation: Department of Dermatology/Andrology Unit, University of Leipzig, Leipzig, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Paasch
authors.affiliation: Department of Andrology, Universitatsklinikum Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Salzbrunn
authors.affiliation: Department of Growth and Reproduction, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Niels Erik
authors.initials: NE
authors.lastname: Skakkebæk
authors.affiliation: University Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Anna-Maria
authors.initials: AM
authors.lastname: Andersson
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005060:Europe; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006801:Humans; D007265:Inhibins / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D012044:Regression Analysis; D060728:Reproductive Health; D012661:Semen / Q000378:metabolism; D055101:Semen Analysis; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism; D014481:United States
chemical_list: D012738:Sex Hormone-Binding Globulin; C422364:inhibin B; D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone
keywords: alcohol; male fertility; reproductive hormones; semen quality