Table 1 Characteristics of the study population

Age, years, n (%)

χ² = 9.584

0.008

  60–70

1,046 (56.41)

785 (57.69)

261 (47.93)

  70–80

574 (29.94)

435 (29.58)

139 (32.33)

  ≥ 80

298 (13.65)

231 (12.74)

67 (19.73)

Gender, n (%)

χ² = 0.350

0.554

  Male

954 (46.45)

687 (46.15)

267 (48.48)

  Female

964 (53.55)

764 (53.85)

200 (51.52)

BMI, kg/m², n (%)

χ² = 7.156

0.067

  <18.5

27 (1.19)

15 (0.88)

12 (3.27)

  18.5–25

494 (25.49)

369 (24.85)

125 (29.75)

  25–30

653 (35.83)

499 (36.60)

154 (30.75)

  ≥30

744 (37.48)

568 (37.67)

176 (36.24)

Race, n (%)

χ² = 195.589

< 0.001

  Mexican American

152 (2.92)

91 (1.99)

61 (9.08)

  Non-Hispanic White

946 (81.49)

831 (85.77)

115 (53.05)

  Non-Hispanic Black

455 (7.46)

283 (5.45)

172 (20.88)

  Other race

365 (8.12)

246 (6.79)

119 (16.99)

Marital status, n (%)

χ² = 25.228

< 0.001

  Married

1,067 (63.92)

842 (66.45)

225 (47.11)

  Widowed/Divorced/Separated

680 (28.74)

486 (26.76)

194 (41.92)

  Never married

117 (4.34)

84 (4.01)

33 (6.54)

  Living with partner

54 (3.00)

39 (2.79)

15 (4.44)

Educational level, n (%)

χ² = 212.195

< 0.001

  Below high school

485 (15.59)

226 (11.05)

259 (45.81)

  High school/GED

457 (22.85)

347 (21.92)

110 (29.02)

  Above high school

976 (61.56)

878 (67.03)

98 (25.17)

Annual household income, dollars, n (%)

χ² = 92.482

< 0.001

  <20,000

512 (16.49)

299 (12.73)

213 (41.47)

  ≥20,000

1,406 (83.51)

1,152 (87.27)

254 (58.53)

Trouble sleeping, n (%)

221 (11.53)

172 (11.59)

49 (11.14)

χ² = 0.044

0.834

Sleeping time, hours, Mean (S.E)

7.12 (0.03)

7.14 (0.04)

7.02 (0.08)

t = 1.210

0.237

Smoking, n (%)

975 (50.99)

715 (50.18)

260 (56.40)

χ² = 3.709

0.054

Drinking, n (%)

590 (26.09)

429 (24.30)

161 (38.01)

χ² = 22.038

< 0.001

Work activity, n (%)

χ² = 15.971

< 0.001

  Vigorous

216 (13.43)

179 (14.27)

37 (7.80)

  Moderate

399 (23.02)

334 (24.30)

65 (14.48)

  Other

1,303 (63.56)

938 (61.43)

365 (77.72)

Recreational activity, n (%)

χ² = 61.881

< 0.001

  Vigorous

165 (11.45)

153 (12.90)

12 (1.78)

  Moderate

625 (33.63)

502 (35.02)

123 (24.40)

  Other

1,128 (54.92)

796 (52.08)

332 (73.82)

Depression, n (%)

148 (5.64)

82 (4.38)

66 (14.03)

χ² = 27.250

< 0.001

Hypertension, n (%)

1,177 (56.69)

872 (55.15)

305 (66.94)

χ² = 10.486

0.001

Diabetes, n (%)

458 (19.61)

300 (17.36)

158 (34.62)

χ² = 22.682

< 0.001

Stroke, n (%)

129 (6.01)

79 (5.25)

50 (11.01)

χ² = 9.044

0.003

CHF, n (%)

133 (6.82)

82 (5.80)

51 (13.61)

χ² = 21.130

< 0.001

CHD, n (%)

167 (8.25)

125 (8.18)

42 (8.74)

χ² = 0.092

0.762

Heart attack, n (%)

166 (8.52)

117 (7.87)

49 (12.84)

χ² = 6.794

0.009

TC, mg/dL Mean (S.E)

195.04 (1.49)

196.32 (1.58)

186.52 (2.43)

t = 3.880

< 0.001

HDL, mg/dL, Mean (S.E)

55.99 (0.88)

56.28 (0.97)

54.04 (1.18)

t = 1.600

0.119

GHb, %, Mean (S.E)

5.94 (0.03)

5.88 (0.04)

6.35 (0.12)

t=-3.760

< 0.001

25(OH)D, nmol/L, Mean (S.E)

82.16 (1.30)

83.52 (1.29)

73.09 (2.65)

t = 4.310

< 0.001

Blood cadmium, µg/L, Mean (S.E)

0.49 (0.02)

0.47 (0.02)

0.63 (0.05)

t=-2.890

0.007

Blood cadmium, µg/L, n (%)

χ² = 26.958

< 0.001

  Normal-level (< 0.60)

1,423 (77.77)

1,112 (79.68)

311 (65.07)

  High-level (≥ 0.60)

495 (22.23)

339 (20.32)

156 (34.93)

Total ω-6 fatty acids intake, mg/kcal/day, Mean (S.E)

8.18 (0.08)

8.30 (0.09)

7.34 (0.17)

t = 4.470

< 0.001

Total ω-6 fatty acids intake, mg/kcal/day, n (%)

χ² = 9.222

0.002

Normal-level (≥ 5.92)

1438 (77.78)

1,111 (79.11)

327 (68.89)

Low-level (< 5.92)

480 (22.22)

340 (20.89)

140 (31.11)