Table 1 Characteristics of the study population by bone mineral density quartiles in the National Health and Nutrition Examination Survey 2011–2018

No

2806

2805

2798

2818

Gender, n (%)

< 0.001

Male

920 (32.79)

1253 (44.67)

1551 (55.43)

1998 (70.90)

Female

1886 (67.21)

1552 (55.33)

1247 (44.57)

820 (29.10)

Age (mean ± SD, year)

38.93 ± 13.45

36.66 ± 12.24

36.62 ± 11.70

36.72 ± 11.76

< 0.001

Race, n (%)

< 0.001

Mexican American

538 (19.17)

437 (15.58)

463 (16.55)

301 (10.68)

Non-Hispanic White

888 (31.65)

1012 (36.08)

972 (34.74)

842 (29.88)

Non-Hispanic Black

278 (9.91)

427 (15.22)

607 (21.69)

1090 (38.68)

Other Race

1102 (39.27)

929 (33.12)

756 (27.02)

585 (20.76)

Marital status, n (%)

< 0.001

Married/ cohabiting

1560 (55.60)

1591 (56.72)

1543 (55.15)

1470 (52.16)

Widowed/divorced/separated

412 (14.68)

322 (11.48)

319 (11.40)

327 (11.60)

Never married

552 (19.67)

664 (23.67)

719 (25.70)

795 (28.21)

Unclear

282 (10.05)

228 (8.13)

217 (7.76)

226 (8.02)

Education, n (%)

< 0.001

Under high school

538 (19.17)

476 (16.97)

481 (17.19)

408 (14.48)

High school or equivalent

545 (19.42)

526 (18.75)

582 (20.80)

585 (20.76)

Above high school

1441 (51.35)

1574 (56.11)

1518 (54.25)

1599 (56.74)

Unclear

282 (10.05)

229 (8.16)

217 (7.76)

226 (8.02)

PIR, n (%)

0.042

≤ 1.26

813 (28.97)

730 (26.02)

748 (26.73)

704 (24.98)

1.27–3.24

822 (29.29)

831 (29.63)

851 (30.41)

836 (29.67)

≥ 3.25

936 (33.36)

1001 (35.69)

962 (34.38)

1052 (37.33)

Unclear

235 (8.37)

243 (8.66)

237 (8.47)

226 (8.02)

BMI (mean ± SD, kg/m²)

26.87 ± 6.40

28.18 ± 6.72

28.99 ± 6.84

29.79 ± 6.63

< 0.001

Activity, n (%)

< 0.001

Active

1716 (61.15)

1555 (55.44)

1466 (52.39)

1430 (50.75)

Less active

171 (6.09)

197 (7.02)

228 (8.15)

204 (7.24)

Inactive

913 (32.54)

1044 (37.22)

1097 (39.21)

1177 (41.77)

Unclear

6 (0.21)

9 (0.32)

7 (0.25)

7 (0.25)

MET scores (median, IQR)

120.00 (60.00-257.50)

130.00 (60.00-300.00)

150.00 (60.00-360.00)

180.00 (80.00-360.00)

< 0.001

Smoking, n (%)

< 0.001

Never

898 (32.00)

946 (33.73)

808 (28.88)

861 (30.55)

Former

196 (6.99)

196 (6.99)

232 (8.29)

232 (8.23)

Current

270 (9.62)

288 (10.27)

335 (11.97)

324 (11.50)

Unclear

1442 (51.39)

1375 (49.02)

1423 (50.86)

1401 (49.72)

Alcohol, n (%)

< 0.001

Yes

1675 (59.69)

1860 (66.31)

1975 (70.59)

2071 (73.49)

No

37 (1.32)

42 (1.50)

64 (2.29)

44 (1.56)

Unclear

1094 (38.99)

903 (32.19)

759 (27.13)

703 (24.95)

Hypertension, n (%)

< 0.001

Yes

650 (23.16)

591 (21.07)

666 (23.80)

815 (28.92)

No

2156 (76.84)

2214 (78.93)

2132 (76.20)

2003 (71.08)

Diabetes, n (%)

0.045

Yes

270 (9.62)

278 (9.91)

265 (9.47)

324 (11.50)

No

2536 (90.38)

2527 (90.09)

2533 (90.53)

2494 (88.50)

Thyroid disease, n (%)

< 0.001

Yes

235 (8.37)

168 (5.99)

143 (5.11)

108 (3.83)

No

2284 (81.40)

2401 (85.60)

2435 (87.03)

2481 (88.04)

Unclear

287 (10.23)

236 (8.41)

220 (7.86)

229 (8.13)

Vitamin D intake (median (IQR), mcg)

3.00 (1.45–5.45)

3.25 (1.55–5.80)

3.25 (1.55–5.80)

3.50 (1.65–6.30)

0.002

Vitamin D supplements (median (IQR), (mcg)

25.00 (10.00–35.00)

25.00 (10.00–35.00)

20.00 (10.05-30.00)

20.00 (10.00-26.48)

0.736

Calcium intake (median (IQR), mg)

792.50 (536.50-1087.25)

834.50 (570.50-1156.25)

876.50 (612.00-1226.75)

921.25 (636.50-1274.50)

< 0.001

Calcium supplements (median (IQR), mg)

333.00 (200.00-535.00)

220.00 (200.00-500.00)

220.00 (200.00-500.00)

210.00 (200.00-500.00)

< 0.001

Vitamin D (mean ± SD, nmol/L)

60.85 ± 26.00

59.97 ± 24.29

59.62 ± 24.26

58.70 ± 24.31

0.015

Total calcium (mean ± SD, mg/dL)

9.37 ± 0.37

9.37 ± 0.34

9.37 ± 0.34

9.40 ± 0.35

0.006

ALT (median (IQR), U/L)

20.00 (15.00–28.00)

20.00 (15.00–28.00)

21.00 (16.00–30.00)

21.00 (16.00–30.00)

0.026

Total Cholesterol (mean ± SD, mg/dL)

191.63 ± 39.68

188.38 ± 41.21

187.19 ± 39.61

185.22 ± 41.59

< 0.001

Serum uric acid (mean ± SD, mg/dL)

5.00 ± 1.30

5.21 ± 1.34

5.41 ± 1.39

5.67 ± 1.39

< 0.001

Visceral fat mass (median (IQR),kg)

0.44 (0.26–0.66)

0.42 (0.26–0.62)

0.43 (0.27–0.62)

0.40 (0.25–0.59)

< 0.001

Lean body mass (mean ± SD,kg)

44.10 ± 10.40

49.30 ± 11.35

53.22 ± 11.58

59.67 ± 12.16

< 0.001

Log LM/VFM

2.00 (1.85–2.19)

2.06 (1.91–2.25)

2.09 (1.94–2.28)

2.17 (2.02–2.35)

< 0.001

Total BMD (mean ± SD,g/cm²)

0.98 ± 0.05

1.08 ± 0.02

1.14 ± 0.02

1.26 ± 0.06

< 0.001