title: Nutritional factors that influence change in bone density and stress fracture risk among young female cross-country runners.
abstract: OBJECTIVE
  To identify nutrients, foods, and dietary patterns associated with stress fracture risk and changes in bone density among young female distance runners.
  
  
  METHODS
  Two-year, prospective cohort study. Observational data were collected in the course of a multicenter randomized trial of the effect of oral contraceptives on bone health.
  
  
  METHODS
  One hundred and twenty-five female competitive distance runners ages 18-26 years.
  
  
  METHODS
  Dietary variables were assessed with a food frequency questionnaire.
  
  
  METHODS
  Bone mineral density and content (BMD/BMC) of the spine, hip, and total body were measured annually by dual x-ray absorptiometry (DEXA). Stress fractures were recorded on monthly calendars, and had to be confirmed by radiograph, bone scan, or magnetic resonance imaging.
  
  
  RESULTS
  Seventeen participants had at least one stress fracture during follow-up. Higher intakes of calcium, skim milk, and dairy products were associated with lower rates of stress fracture. Each additional cup of skim milk consumed per day was associated with a 62% reduction in stress fracture incidence (P < .05); and a dietary pattern of high dairy and low fat intake was associated with a 68% reduction (P < .05). Higher intakes of skim milk, dairy foods, calcium, animal protein, and potassium were associated with significant (P < .05) gains in whole-body BMD and BMC. Higher intakes of calcium, vitamin D, skim milk, dairy foods, potassium, and a dietary pattern of high dairy and low fat were associated with significant gains in hip BMD.
  
  
  CONCLUSIONS
  In young female runners, low-fat dairy products and the major nutrients in milk (calcium, vitamin D, and protein) were associated with greater bone gains and a lower stress fracture rate. Potassium intake was also associated with greater gains in hip and whole-body BMD.
authors: Clinical Research Center, Helen Hayes Hospital, Route 9W, West Haverstraw, NY 10993, USA. jwn5@columbia.edu
authors: Jeri W
authors: JW
authors: Nieves
authors: Kathryn
authors: K
authors: Melsop
authors: Meredith
authors: M
authors: Curtis
authors: Jennifer L
authors: JL
authors: Kelsey
authors: Laura K
authors: LK
authors: Bachrach
authors: Gail
authors: G
authors: Greendale
authors: Mary Fran
authors: MF
authors: Sowers
authors: Kristin L
authors: KL
authors: Sainani
mesh_terms: D000293:Adolescent; D000328:Adult; D015519:Bone Density; D015331:Cohort Studies; D003276:Contraceptives, Oral; D004032:Diet; D005260:Female; D015775:Fractures, Stress / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D009752:Nutritional Status; D012307:Risk Factors; D012420:Running / Q000293:injuries*; D055815:Young Adult
chemical_list: D003276:Contraceptives, Oral