Table 3 Odds ratios for low BMD (lumbar spine T-score < -1 vs. T ≥ -1) for participants’ characteristics from univariate logistic regression models at the baseline

Age (years)

1.082

(1.081, 1.084)

***

Gender

 Male

ref

 Female

1.42

(1.38, 1.46)

***

Education

  < 9 yr

ref

 9—14 yr

0.22

(0.21, 0.23)

***

 14–16 yr

0.12

(0.11, 0.12)

***

 16–18 yr

0.09

(0.09, 0.09)

***

  >  = 18 yr

0.08

(0.08, 0.09)

***

Smoking status

 no, secondhand smoker

ref

 ever smoker and current smoker

0.81

(0.78, 0.84)

***

Physical activity (intensity)

 light exercise

ref

 mean exercise

0.54

(0.52, 0.56)

***

 heavy or violent exercise

0.57

(0.54, 0.61)

***

Sleep score

0.86

(0.85, 0.87)

***

Milk

 no; < 1 cup/wk

ref

  >  = 1 cup/wk

0.99

(0.96, 1.02)

Dairy

 no; < 1 slice of yogurt or cheese/wk

ref

  >  = 1 slice of yogurt or cheese/wk

0.63

(0.61, 0.64)

***

Vegetarian

 No

ref

 Yes

2.40

(2.25, 2.57)

***

BMI

 normal

ref

 underweight

1.21

(1.15, 1.27)

***

 overweight

0.83

(0.80, 0.86)

***

 obesity

0.62

(0.59, 0.65)

***

Waistline

 normal

ref

 central obesity

1.11

(1.07, 1.16)

***

Triglyceride

 normal

ref

  >  = 150 mg/dl

1.22

(1.18, 1.26)

***

Uric acid

 normal

ref

 hyperuricemia

0.85

(0.83, 0.89)

***

Walkability (park and elementary school; 1 km buffer)

0.986

(0.984, 0.988)

***

Annual average solar radiation

1.01

(1.01, 1.02)

***