title: Higher serum phenylalanine concentration is associated with more rapid telomere shortening in men.
abstract: Telomere length and telomere shortening are associated with age-related health outcomes. Only a few studies have been able to longitudinally report on factors that are associated with changes in telomere length in an aging population.
  
  
  
  We studied the longitudinal relation between telomere length, the change in telomere length, and circulating amino acids.
  
  
  
  A total of 812 subjects from the Helsinki Birth Cohort Study (born from 1934 to 1944), who underwent 3 clinical visits during a 10-y interval that included measurements of cardiometabolic risk factors, were included in the study. Leukocyte telomere length (LTL) was measured with the use of quantitative real-time polymerase chain reaction. Circulating branched-chain and aromatic amino acids (alanine, glycine, histidine, phenylalanine, leucine, isoleucine, valine, and tyrosine) were assessed with the use of high-throughput nuclear magnetic resonance spectroscopy.
  
  
  
  The relative ± SD LTL at a mean age of 71 y was 0.79 ± 0.27 in men and 0.89 ± 0.35 in women (P < 0.001). Of the studied amino acids, the strongest inverse association was observed between the phenylalanine concentration that was measured 5 y earlier and the LTL. This finding was significant in men (P = 0.021) and remained significant after adjustment for multiple comparisons, but it was not significant in women (P = 0.39). Longitudinally, the change in LTL over 10 y was inversely associated with the phenylalanine concentration in men (P = 0.007) but not in women (P = 0.58) after adjustment for baseline LTL, age, smoking, and percentage of body fat.
  
  
  
  The serum phenylalanine concentration is associated with telomere length and, therefore, potentially with the aging process. Because the associations reported are observational, no conclusions can be made regarding causality. Our findings support the hypothesis that cellular pathways that regulate aging are sex specific.
authors.affiliation: Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland; johan.eriksson@helsinki.fi.|Department of General Practice and Primary Health Care, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.|Folkhälsan Research Center, Helsinki, Finland.
authors.forename: Johan G
authors.initials: JG
authors.lastname: Eriksson
authors.affiliation: Insitute of Clinical Physiology, National Research Council, Pisa, Italy.
authors.forename: Maria-Angela
authors.initials: MA
authors.lastname: Guzzardi
authors.affiliation: Insitute of Clinical Physiology, National Research Council, Pisa, Italy.
authors.forename: Patricia
authors.initials: P
authors.lastname: Iozzo
authors.affiliation: Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland.|Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.|Department of Obstetrics and Gynecology, MRC Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Kajantie
authors.affiliation: Department of General Practice and Primary Health Care, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.|Folkhälsan Research Center, Helsinki, Finland.|University of Eastern Finland, Kuopio Finland.
authors.forename: Hannu
authors.initials: H
authors.lastname: Kautiainen
authors.affiliation: Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland.|Folkhälsan Research Center, Helsinki, Finland.
authors.forename: Minna K
authors.initials: MK
authors.lastname: Salonen
mesh_terms: D000368:Aged; D000375:Aging / Q000097:blood*; D000596:Amino Acids / Q000097:blood; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005387:Finland; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010649:Phenylalanine / Q000097:blood*; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors; D012737:Sex Factors; D016615:Telomere; D059506:Telomere Shortening
chemical_list: D000596:Amino Acids; D010649:Phenylalanine
keywords: aging; amino acids; longitudinal study; phenylalanine; telomere shortening; telomeres