title: The effects of male age on sperm DNA damage in healthy non-smokers.
abstract: BACKGROUND
  The trend for men to have children at older age raises concerns that advancing age may increase the production of genetically defective sperm, increasing the risks of transmitting germ-line mutations.
  
  
  METHODS
  We investigated the associations between male age and sperm DNA damage and the influence of several lifestyle factors in a healthy non-clinical group of 80 non-smokers (mean age: 46.4 years, range: 22-80 years) with no known fertility problems using the sperm Comet analyses.
  
  
  RESULTS
  The average percentage of DNA that migrated out of the sperm nucleus under alkaline electrophoresis increased with age (0.18% per year, P = 0.006), but there was no age association for damage measured under neutral conditions (P = 0.7). Men who consumed >3 cups coffee per day had approximately 20% higher percentage tail DNA under neutral but not alkaline conditions compared with men who consumed no caffeine (P = 0.005).
  
  
  CONCLUSIONS
  Our findings indicate that (i) older men have increased sperm DNA damage associated with alkali-labile sites or single-strand DNA breaks and (ii) independent of age, men with substantial daily caffeine consumption have increased sperm DNA damage associated with double-strand DNA breaks. DNA damage in sperm can be converted to chromosomal aberrations and gene mutations after fertilization, increasing the risks of developmental defects and genetic diseases among offspring.
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Schmid
authors.forename: B
authors.initials: B
authors.lastname: Eskenazi
authors.forename: A
authors.initials: A
authors.lastname: Baumgartner
authors.forename: F
authors.initials: F
authors.lastname: Marchetti
authors.forename: S
authors.initials: S
authors.lastname: Young
authors.forename: R
authors.initials: R
authors.lastname: Weldon
authors.forename: D
authors.initials: D
authors.lastname: Anderson
authors.forename: A J
authors.initials: AJ
authors.lastname: Wyrobek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage; D003069:Coffee / Q000009:adverse effects; D020552:Comet Assay; D004249:DNA Damage / Q000502:physiology*; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D013076:Sperm Count; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D003069:Coffee; D002110:Caffeine