title: Associations between a posteriori defined dietary patterns and bone mineral density in adolescents.
abstract: OBJECTIVE
  Dietary pattern analysis may uncover the joint effects of multiple dietary components on bone health, but such research is scarce and targets mostly adults.
  
  
  METHODS
  We quantified prospective associations between dietary patterns and bone mineral density (BMD) in 1,007 adolescents of a cohort born in 1990 and recruited at schools in Porto during the 2003/2004 school year. Forearm BMD was measured using dual-energy X-ray absorptiometry. Participants' dietary patterns were classified "Healthier", "Dairy products", "Fast food and sweets" and "Lower intake" according to previously identified patterns obtained in a larger sample of 1,489 participants using the K-means method. Using dietary patterns at 13 years old as the main exposure, associations were estimated cross-sectionally (with BMD at the age of 13) and prospectively (with annual BMD variation between 13 and 17 years), using linear regression coefficients adjusted for height, weight, energy intake and, in girls, for menarche age.
  
  
  RESULTS
  No significant associations between the a posteriori dietary patterns identified and mean BMD at 13 were found. However, among girls, adherence to a pattern characterized by low intake of energy and all food groups was negatively associated with annual BMD variation between 13 and 17 years [adjusted coefficient (95 % CI) -0.451 (-0.827; -0.074) mg·cm⁻²·year⁻¹].
  
  
  CONCLUSIONS
  Although results showed that, in girls, adherence to a "Lower intake" dietary pattern is associated with lower annual BMD variation throughout adolescence, overall, there were no consistent associations between dietary patterns and forearm BMD in adolescents.
authors.affiliation: Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal, teresam@med.up.pt.
authors.forename: Teresa
authors.initials: T
authors.lastname: Monjardino
authors.forename: Raquel
authors.initials: R
authors.lastname: Lucas
authors.forename: Elisabete
authors.initials: E
authors.lastname: Ramos
authors.forename: Carla
authors.initials: C
authors.lastname: Lopes
authors.forename: Rita
authors.initials: R
authors.lastname: Gaio
authors.forename: Henrique
authors.initials: H
authors.lastname: Barros
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D041923:Adolescent Development; D017195:Adolescent Nutritional Physiological Phenomena; D001499:Bayes Theorem; D015519:Bone Density; D001846:Bone Development; D016000:Cluster Analysis; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004032:Diet / Q000009:adverse effects* / Q000145:classification; D005260:Female; D005542:Forearm; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011174:Portugal; D011446:Prospective Studies; D012727:Sex Characteristics; D014504:Urban Health