title: Low seminal plasma folate concentrations are associated with low sperm density and count in male smokers and nonsmokers.
abstract: OBJECTIVE
  To measure folate levels in seminal plasma from smokers and nonsmokers and to evaluate relationships between seminal plasma folate levels and both folate nutriture and semen quality measures.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  United States Department of Agriculture, Western Human Nutrition Research Center, Presidio of San Francisco, San Francisco, California.
  
  
  METHODS
  Healthy male smokers (n=24) and nonsmokers (n=24).
  
  
  METHODS
  Blood levels of plasma folate and homocysteine, seminal plasma total, non-methyl- and 5-methyltetrahydrofolate concentrations, and total sperm count and density.
  
  
  RESULTS
  Total seminal plasma folate concentrations were on average 1.5 times higher than blood plasma folate concentrations in all men. Seminal plasma folates contained 5-methyltetrahyrdofolate (74% of total) and non-methyltetrahydrofolates (26% of total); all samples had less than four glutamyl residues. Total and 5-methyltetrahydrofolate concentrations correlated significantly with blood plasma folate and homocysteine concentrations. Seminal plasma non-methyltetrahydrofolate levels correlated significantly with sperm density and total sperm count. Seminal plasma of smokers contained a proportionally lower concentration of non-methyltetrahydrofolates compared with nonsmokers.
  
  
  CONCLUSIONS
  Seminal plasma total folate and 5-methyltetrahydrofolate concentrations reflect folate nutriture. The non-methyltetrahydrofolate fraction of seminal plasma may be important for male reproductive function.
authors.affiliation: USDA, Agricultural Research Service, Western Human Nutrition Research Center, Presidio of San Francisco, California, USA. lwallock@chori.org
authors.forename: L M
authors.initials: LM
authors.lastname: Wallock
authors.forename: T
authors.initials: T
authors.lastname: Tamura
authors.forename: C A
authors.initials: CA
authors.lastname: Mayr
authors.forename: K E
authors.initials: KE
authors.lastname: Johnston
authors.forename: B N
authors.initials: BN
authors.lastname: Ames
authors.forename: R A
authors.initials: RA
authors.lastname: Jacob
mesh_terms: D000328:Adult; D004032:Diet; D005492:Folic Acid / Q000032:analysis* / Q000097:blood; D005838:Genotype; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D009154:Mutation; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics*; D012661:Semen / Q000737:chemistry*; D012907:Smoking; D013076:Sperm Count; D013094:Spermatozoa / Q000737:chemistry; D013763:Tetrahydrofolates / Q000097:blood; D014805:Vitamin B 12 / Q000097:blood; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D013763:Tetrahydrofolates; D014815:Vitamins; D006710:Homocysteine; D005492:Folic Acid; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D014805:Vitamin B 12; C005984:5-methyltetrahydrofolate