title: Is soy intake related to age at onset of menarche? A cross-sectional study among adolescents with a wide range of soy food consumption.
abstract: BACKGROUND
  Early onset of menarche may negatively influence the future health of adolescent girls. Several factors affect the timing of menarche but it is not clear if soy foods consumption around pubertal years plays a role; thus, we examined its relation to age at onset of menarche (AOM) in a high soy-consuming population.
  
  
  METHODS
  We conducted a cross-sectional study on 339 girls ages 12-18 years attending middle and high schools near two Seventh-day Adventist universities in California and Michigan using a web-based dietary questionnaire and physical development tool. Soy consumption (categorized as total soy, meat alternatives, tofu/traditional soy, and soy beverages) was estimated from the questionnaire, while AOM was self-reported. Data analyses included descriptive statistics, Cox proportional hazards ratios, Kaplan-Meier curves and Poisson regression with adjustment for relevant confounders.
  
  
  RESULTS
  Mean (SD) intakes were: total soy,12.9 (14.4) servings/week; meat alternatives, 7.0 (8.9) servings/week; tofu/traditional soy foods, 2.1 (3.8) servings/week; soy beverages, 3.8 (6.3) servings/week. Mean AOM was 12.5 (1.4) y for those who reached menarche. Consumption of total soy and the 3 types of soy foods was not significantly associated with AOM and with the odds for early- or late-AOM. Adjustment for demographic and dietary factors did not change the results.
  
  
  CONCLUSIONS
  Soy intake is not associated with AOM in a population of adolescent girls who have a wide range of, and relatively higher, soy intake than the general US population. Our finding suggests that the increasing popularity of soy in the US may not be associated with AOM.
authors.affiliation: Department of Nutrition, Loma Linda University, 24951 North Circle Dr,, Nichol Hall 1105, Loma Linda, CA 92350, USA. gsiapco@llu.edu.
authors.forename: Gina
authors.initials: G
authors.lastname: Segovia-Siapco
authors.forename: Peter
authors.initials: P
authors.lastname: Pribis
authors.forename: Mark
authors.initials: M
authors.lastname: Messina
authors.forename: Keiji
authors.initials: K
authors.lastname: Oda
authors.forename: Joan
authors.initials: J
authors.lastname: Sabaté
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008572:Menarche; D045730:Soy Foods