title: Associations of Protein Intake and Protein Source with Bone Mineral Density and Fracture Risk: A Population-Based Cohort Study.
abstract: High dietary protein has been hypothesized to cause lower bone mineral density (BMD) and greater fracture risk. Previous results are conflicting and few studies have assessed potential differences related to differing protein sources.
  
  
  OBJECTIVE
  To determine associations between total protein intake, and protein intake by source (dairy, non-dairy animal, plant) with BMD, BMD change, and incident osteoporotic fracture.
  
  
  METHODS
  Prospective cohort study (Canadian Multicentre Osteoporosis Study). Participants/Measures: Protein intake was assessed as percent of total energy intake (TEI) at Year 2 (1997-99) using a food frequency questionnaire (N=6510). Participants were contacted annually to ascertain incident fracture. Total hip and lumbar spine BMD was measured at baseline and Year 5. Analyses were stratified by group (men 25-49 y, men 50+ y, premenopausal women 25-49 y, and postmenopausal women 50+ y) and adjusted for major confounders. Fracture analyses were limited to those 50+ y.
  
  
  RESULTS
  Intakes of dairy protein (with adjustment for BMI) were positively associated with total hip BMD among men and women aged 50+ y, and in men aged 25-49. Among adults aged 50+ y, those with protein intakes of <12% TEI (women) and <11% TEI (men) had increased fracture risk compared to those with intakes of 15% TEI. Fracture risk did not significantly change as intake increased above 15% TEI, and was not significantly associated with protein source.
  
  
  CONCLUSIONS
  In contrast to hypothesized risk of high protein, we found that for adults 50+ y, low protein intake (below 15% TEI) may lead to increased fracture risk. Source of protein was a determinant of BMD, but not fracture risk.
authors.affiliation: David Goltzman, Royal Victoria Hospital, CaMos, 687 Pine Ave W, Room E1.64, Montreal, QC H3A 1A1, Email: david.goltzman@mcgill.ca, Telephone: 514-843-1632, FAX: 514-843-1651.
authors.forename: L
authors.initials: L
authors.lastname: Langsetmo
authors.forename: S I
authors.initials: SI
authors.lastname: Barr
authors.forename: C
authors.initials: C
authors.lastname: Berger
authors.forename: N
authors.initials: N
authors.lastname: Kreiger
authors.forename: E
authors.initials: E
authors.lastname: Rahme
authors.forename: J D
authors.initials: JD
authors.lastname: Adachi
authors.forename: A
authors.initials: A
authors.lastname: Papaioannou
authors.forename: S M
authors.initials: SM
authors.lastname: Kaiser
authors.forename: J C
authors.initials: JC
authors.lastname: Prior
authors.forename: D A
authors.initials: DA
authors.lastname: Hanley
authors.forename: C S
authors.initials: CS
authors.lastname: Kovacs
authors.forename: R G
authors.initials: RG
authors.lastname: Josse
authors.forename: D
authors.initials: D
authors.lastname: Goltzman
mesh_terms: D000328:Adult; D000818:Animals; D015519:Bone Density / Q000502:physiology*; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D004032:Diet; D004044:Dietary Proteins; D002149:Energy Intake; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000453:epidemiology*; D058866:Osteoporotic Fractures / Q000453:epidemiology*; D017697:Premenopause; D011446:Prospective Studies; D012306:Risk; D011795:Surveys and Questionnaires
chemical_list: D004044:Dietary Proteins