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Table 1 Demographic characteristics of participants as a whole and according to categories of total soy consumption level

From: Is soy intake related to age at onset of menarche? A cross-sectional study among adolescents with a wide range of soy food consumption

  Total (n = 327) count (%) Level of soy consumption (frequency of intake) p-value
≤1×/week (n = 62) count (%) >1×/week - ≤1×/day (n = 85) count (%) >1×/day - ≤3×/day (n = 111) count (%) >3×/day (n = 69) count (%)
Age, years       0.574b
  12 26 (8.0%) 6 (9.7%) 7 (8.2%) 9 (8.1%) 4 (5.8%)  
  13 51 (15.6%) 8 (12.9%) 13 (15.3%) 19 (17.1%) 11 (15.9%)  
  14 56 (17.1%) 9 (14.5%) 17 (20.0%) 19 (17.1%) 11 (15.9%)  
  15 61 (18.7%) 7 (11.3%) 18 (21.2%) 19 (17.1%) 17 (24.6%)  
  16 59 (18.0%) 14 (22.6%) 8 (9.4%) 21 (18.9%) 16 (23.2%)  
  17 50 (15.3%) 14 (22.6%) 15 (17.6%) 14 (12.6%) 7 (10.1%)  
  18 24 (7.3%) 4 (6.5%) 7 (8.2%) 10 (9.0%) 3 (4.3%)  
Mean age (SD), years 15.0 (1.5) 15.2 (1.8) 14.9 (1.8) 14.9 (1.8)1 14.9 (1.5) 0.771c
Site       0.006b
  Michigan 152 (46.5%) 41 (66.1%) 36 (42.4%) 49 (44.1%) 26 (37.7%)  
  California 175 (53.5%) 21 (33.9%) 49 (57.6%) 62 (55.9%) 43 (62.3%)  
School       <.0001b
  Public 38 (11.6%) 23 (37.1%) 8 (9.4%) 4 (3.6%) 3 (4.3%)  
  Private 289 (88.4%) 39 (62.9%) 77 (90.6%) 107 (96.4%) 66 (95.7%)  
Mother’s education       0.0008b
  High school level/graduate 63 (19.3%) 24 (38.7%) 13 (15.3%) 13 (11.7%) 13 (18.8%)  
  College level/degree 133 (40.7%) 26 (41.9%) 41 (48.2%) 50 (45.0%) 30 (43.5%)  
  Masters/Doctoral level/degree 131 (40.1%) 12 (19.4%) 31 (36.5%) 48 (43.2%) 26 (37.7%)  
Father’s education       0.0001b
  High school level/graduate 68 (20.8%) 24 (38.7%) 21 (24.7%) 13 (11.7%) 10 (14.5%)  
  College level/degree 113 (34.6%) 28 (45.2%) 35 (41.2%) 43 (38.7%) 21 (30.4%)  
  Masters/Doctoral level/degree 146 (44.6%) 10 (16.1%) 29 (34.1%) 55 (49.5%) 38 (55.1%)  
Mother’s ethnicity       0.0004b
  White 142 (43.4%) 35 (56.5%) 34 (40.0%) 52 (46.8%) 21 (30.4%)  
  Black 34 (10.4%) 3 (4.8%) 10 (11.8%) 13 (11.7%) 8 (11.6%)  
  Hispanic 65 (19.9%) 15 (24.2%) 15 (17.6%) 16 (14.4%) 19 (27.5%)  
  Asian 50 (15.3%) 3 (4.8%) 8 (9.4%) 22 (19.8%) 17 (24.6%)  
  Other 36 (11.0%) 6 (9.7%) 18 (21.2%) 8 (7.2%) 4 (5.8%)  
Father’s ethnicity       0.004b
  White 144 (44.0%) 36 (58.1%) 31 (36.5%) 53 (47.7%) 24 (34.8%)  
  Black 41 (12.5%) 4 (6.5%) 14 (16.5%) 15 (13.5%) 8 (11.6%)  
  Hispanic 60 (18.3%) 12 (19.4%) 15 (17.6%) 16 (14.4%) 17 (24.6%)  
  Asian 46 (14.1%) 2 (3.2%) 9 (10.6%) 20 (18.0%) 15 (21.7%)  
  Other 36 (11.0%) 8 (12.9%) 16 (18.8%) 7 (6.3%) 5 (7.2%)  
Meat intake, frequency/week      <.0001b
  Never 79 (24.2%) 0 (0.0%) 8 (9.4%) 40 (36.0%) 31 (44.9%)  
  ≤1x/day 111 (33.9%) 17 (27.4%) 38 (44.7%) 39 (35.1%) 17 (24.6%)  
  >1x/day 137 (41.9%) 45 (72.6%) 39 (45.9%) 32 (28.8%) 21 (30.4%)  
Median meat intake (IQR), svg/d 5.5 (12.5) 13.3 (12.5) 7.0 (8.0) 2.0 (8.0) 1.5 (10.0) <.0001d
Median BMI (IQR), kg/m 2 21.9 (4.2) 22.3 (3.7) 22.7 (4.7) 21.3 (4.1) 21.5 (3.8) 0.088d
Mean BMI z-score (SD) 0.43 (1.02) 0.57 (0.92) 0.62 (1.14) 0.28 (0.98) 0.34 (1.01) 0.084c
Age at onset of menarche (AOM)       0.498b
  ≤9 13 (4.0%) 3 (4.8%) 4 (4.7%) 4 (3.6%) 2 (2.9%)  
  10 27 (8.3%) 6 (9.7%) 10 (11.8%) 7 (6.3%) 4 (5.8%)  
  11 39 (11.9%) 2 (3.2%) 12 (14.1%) 13 (11.7% ) 12 (17.4%)  
  12 122 (37.3%) 30 (48.4%) 26 (30.6%) 43 (38.7%) 23 (33.3%)  
  13 48 (14.7%) 7 (11.3%) 11 (12.9%) 19 (17.1%) 11 (15.9%)  
  14 33 (10.1%) 5 (8.1%) 8 (9.4%) 10 (9.0%) 10 (14.5%)  
  ≥15 11 (3.4%) 2 (3.2%) 4 (4.7%) 4 (3.6%) 1 (1.4%)  
  Not yet 34 (10.4%) 7 (11.3%) 10 (11.8%) 11 (9.9%) 6 (8.7%)  
Mean AOM (SD) a 12.5 (1.4) 12.5 (1.4) 12.4 (1.6) 12.6 (1.3) 12.6 (1.3) 0.835
  1. aExcludes those who have no menarche as yet.
  2. bChi-square test.
  3. cOne-way ANOVA.
  4. dKruskal-Wallis test.