Table 1 Baseline characteristics of study participants stratified by serum β-carotene quartiles

Age (year)

46.29 ± 0.47

41.82 ± 0.54

44.11 ± 0.57

47.68 ± 0.74

52.49 ± 0.69

< 0.001

Sex, n (%)

< 0.001

 Female

2430 (49.74)

476 (37.74)

570 (48.47)

635 (52.42)

749 (62.38)

 Male

2654 (50.26)

796 (62.26)

703 (51.53)

637 (47.58)

518 (37.62)

Race, n (%)

0.071

 Non-Hispanic White

2742 (74.17)

675 (72.97)

689 (75.17)

653 (72.06)

725 (76.55)

 Non-Hispanic Black

969 (10.04)

295 (11.63)

241 (10.00)

226 (10.16)

207 (8.13)

 Mexican American

1035 (7.35)

213 (6.28)

262 (7.28)

303 (8.99)

257 (7.03)

 Others

338 (8.44)

89 (9.12)

81 (7.54)

90 (8.79)

78 (8.29)

Education level, n (%)

< 0.001

 Less than high school

1402 (17.19)

369 (20.54)

366 (18.62)

350 (14.88)

317 (14.05)

 High school

1251 (26.56)

374 (32.54)

327 (27.27)

307 (26.22)

243 (19.15)

 College or above

2431 (56.25)

529 (46.92)

580 (54.11)

615 (58.89)

707 (66.80)

Marital, n (%)

< 0.001

 Married

2860 (59.00)

604 (51.55)

711 (57.45)

759 (61.29)

786 (67.08)

 Separated

1463 (25.48)

410 (29.19)

345 (25.28)

344 (24.05)

364 (22.82)

 Unmarried

761 (15.52)

258 (19.27)

217 (17.27)

169 (14.66)

117 (10.10)

Smoking status, n (%)

< 0.001

 Never

2493 (48.38)

499 (38.37)

584 (45.80)

690 (54.38)

720 (56.81)

 Former

1426 (26.13)

269 (19.62)

358 (26.03)

366 (26.83)

433 (33.09)

 Now

1165 (25.49)

504 (42.01)

331 (28.17)

216 (18.79)

114 (10.10)

Alcohol user, n (%)

< 0.001

 Never

683 (11.53)

115 (7.43)

170 (11.85)

179 (12.88)

219 (14.57)

 Former

1089 (17.45)

244 (16.88)

271 (17.76)

296 (17.87)

278 (17.35)

 Now

3312 (71.02)

913 (75.69)

832 (70.40)

797 (69.25)

770 (68.08)

Family of poverty ratio, n (%)

< 0.001

 < 1.3

1286 (17.85)

412 (23.55)

331 (18.12)

314 (16.55)

229 (12.25)

 1.3–3.5

2022 (37.34)

509 (40.52)

534 (40.16)

488 (35.83)

491 (32.02)

 >3.5

1776 (44.81)

351 (35.93)

408 (41.72)

470 (47.62)

547 (55.73)

BMI (kg/m²)

28.35 ± 0.12

30.09 ± 0.21

28.65 ± 0.24

28.07 ± 0.20

26.29 ± 0.18

< 0.001

Total cholesterol (mmol/L)

5.16 ± 0.02

4.91 ± 0.03

5.09 ± 0.04

5.29 ± 0.04

5.39 ± 0.04

< 0.001

Leisure-time physical activity

< 0.001

 Yes

1356 (29.83)

281 (22.79)

336 (29.71)

329 (29.84)

410 (38.14)

 No

3728 (70.17)

991 (77.21)

937 (70.29)

943 (70.16)

857 (61.86)

CVD, n (%)

0.460

 Yes

576 (8.31)

132 (7.81)

153 (9.20)

131 (7.72)

160 (8.49)

 No

4508 (91.69)

1140 (92.19)

1120 (90.80)

1141 (92.28)

1107 (91.51)

Hypertension, n (%)

0.040

 Yes

2178 (36.59)

560 (39.92)

523 (36.35)

542 (35.34)

553 (34.24)

 No

2906 (63.41)

712 (60.08)

750 (63.65)

730 (64.66)

714 (65.76)

Diabetes, n (%)

0.002

 Yes

650 (8.95)

207 (11.89)

159 (8.29)

147 (7.70)

137 (7.51)

 No

4434 (91.05)

1065 (88.11)

1114 (91.71)

1125 (92.30)

1130 (92.49)

α-carotene (ug/dL)

4.24 ± 0.18

1.28 ± 0.04

2.48 ± 0.05

4.22 ± 0.13

9.66 ± 0.45

< 0.001

β-cryptoxanthin (ug/dL)

8.93 ± 0.18

4.85 ± 0.10

7.22 ± 0.17

10.18 ± 0.24

14.33 ± 0.32

< 0.001

Lutein/zeaxanthin (ug/dL)

15.58 ± 0.22

10.82 ± 0.17

13.84 ± 0.24

16.78 ± 0.25

21.82 ± 0.42

< 0.001

Trans-lycopene (ug/dL)

23.05 ± 0.26

19.10 ± 0.34

23.43 ± 0.40

24.52 ± 0.41

25.74 ± 0.42

< 0.001