title: The roles of adulthood behavioural factors and familial influences in bone density among men.
abstract: BACKGROUND
  A primary strategy in osteoporosis prevention is advice on exercise, smoking, and calcium intake, although its practical value is unclear.
  
  
  OBJECTIVE
  To investigate the roles of such factors on bone density (BMD) after considering the influences of familial aggregation (combined effects of genetics and familial influences) in Finnish men 35-69 years old.
  
  
  METHODS
  We selected 105 male monozygotic twin pairs, with discordance in suspected determinants.
  
  
  RESULTS
  Dietary calcium was associated with BMD of the femoral neck; and body weight and lifetime frequency of endurance and ball game sport activities were associated with both femoral neck and lumbar BMD. Occupational loading and smoking were associated with neither. However, age and familial aggregation explained 73% of the variance of BMD in both the femoral neck and lumbar spine; calcium intake explained 1% in femoral neck and lifetime exercise 1% in lumbar spine.
  
  
  CONCLUSIONS
  The effects of dietary calcium and physical activity that are not 'embedded' in the familial influences had very modest effects on the variance of BMD. Thus our chances of influencing BMD in later adulthood by targeting behavioural habits are likely to be limited. Interventions focused on childhood and the family unit may achieve more beneficial long-term results.
authors.affiliation: University of Alberta, Faculty of Rehabilitation Medicine, Edmonton, Canada. tapio.videman@ualberta.ca
authors.forename: Tapio
authors.initials: T
authors.lastname: Videman
authors.forename: Michele C
authors.initials: MC
authors.lastname: Batti
authors.forename: Laura E
authors.initials: LE
authors.lastname: Gibbons
authors.forename: Esko
authors.initials: E
authors.lastname: Vanninen
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.forename: Markku
authors.initials: M
authors.lastname: Koskenvuo
mesh_terms: D000328:Adult; D015519:Bone Density / Q000235:genetics; D002136:Calcium, Dietary / Q000008:administration & dosage; D015444:Exercise; D005192:Family Health; D005272:Femur Neck / Q000502:physiology; D015438:Health Behavior; D006801:Humans; D016018:Least-Squares Analysis; D008019:Life Style; D008159:Lumbar Vertebrae / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000517:prevention & control / Q000523:psychology; D012907:Smoking; D014430:Twins, Monozygotic
chemical_list: D002136:Calcium, Dietary