Table 1 Population characteristics by quintiles of dietary heme and non-heme iron intake

Male, n(%)

658(40.2)

709(43.4)

904(55.3)

< 0.001

469(28.7)

784(48.0)

1003(61.3)

< 0.001

Age, years

49.0(38.0,60.0)

47(37.0,58.0)

46(35.5,54.0)

< 0.001

52.0(39.0,65.0)

47.0(37.0,56.0)

45.0(37.0,54.0)

< 0.001

Body mass index, kg/m²

21.8(20.1,24.2)

21.7(20.0,24.0)

21.5(19.8,24.0)

< 0.001

21.9(20.0,24.4)

21.8(20.0,23.9)

21.6(19.9,23.7)

0.103

Systolic BP, mmHg

116.7(105.0,124,7)

112.0(104.7,122.0)

110.7(104.0,120.7)

< 0.001

118.0(106.7,129.3)

112.0(104.5,121.7)

111.3(104.7,120.7)

< 0.001

Diastolic BP, mmHg

76.0(70.0,80.5)

75.0(68.7,80.0)

74.0(69.3,80.0)

< 0.001

76.7(70.0,82.0)

75.0(69.3,80.0)

75.0(70.0,80.0)

< 0.001

Smoke, n(%)

355(21.7)

320(19.6)

356(21.8)

0.440

298(18.2)

381(23.3)

361(22.1)

0.003

Drinking Alcohol, n(%)

191(11.7)

256(15.7)

301(18.4)

< 0.001

192(11.7)

271(16.6)

280(17.1)

< 0.001

Diabetes, n(%)

10(0.6)

18(1.1)

16(1.0)

0.244

20(1.2)

16(1.0)

12(0.7)

0.143

Hypertension, n(%)

73(4.5)

72(4.4)

64(3.9)

0.690

95(5.8)

46(2.8)

52(3.2)

< 0.001

Urban Residence, n(%)

260(15.9)

551(33.7)

775(47.4)

< 0.001

577(35.3)

547(33.5)

482(29.5)

0.005

Education level, n(%)

< 0.001

< 0.001

Primary school or lower

1087(66.5)

829(50.7)

635(38.8)

889(54.4)

828(50.6)

763(46.7)

Middle school

511(31.3)

719(44.0)

904(55.3)

661(40.4)

721(44.1)

802(49.1)

college or above

9(0.6)

55(3.4)

77(4.7)

55(3.4)

61(3.7)

47(2.9)

Occupation, n(%)

< 0.001

< 0.001

Farmer

982(60.1)

704(43.1)

463(28.3)

561(34.3)

718(43.9)

791(48.4)

Worker

181(11.1)

245(15.0)

380(23.2)

292(17.9)

264(16.1)

275(16.8)

Other

472(28.9)

686(42.0)

792(48.4)

782(47.8)

653(39.9)

569(34.8)

Dietary intake

Heme iron, mg/day

0.1(0.0,0.2)

0.8(0.7,0.9)

2.0(1.7,2.6)

< 0.001

0.6(0.3,0.9)

0.8(0.4,1.4)

1.0(0.4,1.6)

< 0.001

Nonheme iron, mg/day

17.3(14.3,21.5)

17.9(14.9,21.3)

20.2(17.4,24.1)

< 0.001

12.8(11.5,13.7)

18.2(17.6,18.9)

26.8(24.7,30.7)

< 0.001

Iron, mg/day

17.5(14.4,21.6)

18.7(15.7,22.1)

22.5(19.5,26.6)

< 0.001

13.5(12.0,14.4)

19.2(18.4,19.9)

28.2(25.8,32.2)

< 0.001

Energy, Kcal/day

2473.2(1925.1,3019.0)

2347.2(1918.7,2810.2)

2387.3(2012.0,2864.4)

< 0.001

2097.1(1648.5,2544.9)

2406.3(2019.2,2866.7)

2677.3(2199.9,3184.6)

< 0.001

Fat, g/day

41.5(28.1,60.7)

61.8(42.7,88.5)

74.9(51.4,100.6)

< 0.001

56.9(38.1,81.6)

60.1(39.4,88.6)

59.7(39.4,90.0)

0.001

Carbohydrate, g/day

427.9(324.1,558.1)

361.0(273.9,446.1)

337.2(269.7,421.1)

< 0.001

316.5(232.9,404.6)

370.4(294.4,465.3)

420.8(327.5,535.3)

< 0.001

Protein, g/day

69.2(53.0,88.1)

67.4(54.3,83.3)

74.7(62.2,91.1)

< 0.001

60.2(47.4,75.3)

71.4(57.7,86.1)

77.9(64.1,96.4)

< 0.001

Biomarkers

Ferritin, ng/ml

74.0(38.0,133.6)

75.1(37.7,143.0)

94.9(46.4,171.1)

< 0.001

69.3(32.5,128.0)

81.0(43.3,146.9)

89.1(45.9,155.8)

< 0.001

Transferrin, mg/dl

287.5(257.0,324.0)

282.0(248.0,318.0)

280.0(250.8,314.0)

< 0.001

279.0(250.0,316.0)

282.0(252.0,316.0)

283.0(252.0,320.0)

0.152

Transferrin receptor, mg/L

1.3(1.1,1.6)

1.4(1.1,1.7)

1.3(1.1,1.6)

0.082

1.4(1.1,1.7)

1.4(1.1,1.6)

1.3(1.1,1.6)

< 0.001

LDL-C, mmol/L

2.9(2.3,3.5)

2.9(2.3,3.5)

3.0(2.4,3.6)

0.059

3.0(2.3,3.7)

2.9(2.3,3.5)

2.9(2.4,3.5)

< 0.001

HDL-C, mmol/L

1.4(1.2,1.6)

1.4(1.2,1.6)

1.4(1.1,1.6)

< 0.001

1.4(1.2,1.7)

1.4(1.1,1.6)

1.4(1.2,1.7)

0.006

Total cholesterol, mmol/L

4.7(4.1,5.4)

4.8(4.2,5.4)

4.9(4.3,5.6)

< 0.001

4.8(4.2,5.5)

4.8(4.2,5.5)

4.8(4.2,5.4)

0.025

Triglycerides, mmol/L

1.2(0.8,1.9)

1.2(0.8,2.0)

1.3(0.9,2.1)

< 0.001

1.3(0.9,1.9)

1.3(0.9,2.0)

1.2(0.8,1.9)

0.109

Apolipoprotein A1, g/L

1.07(0.93,1.24)

1.09(0.94,1.28)

1.12(0.96,1.35)

< 0.001

1.10(0.95,1.31)

1.10(0.95,1.29)

1.09(0.93,1.28)

0.009

Apolipoprotein B, g/L

0.85(0.71,1.03)

0.88(0.73,1.06)

0.92(0.76,1.12)

< 0.001

0.90(0.74,1.09)

0.88(0.72,1.07)

0.88(0.73,1.07)

0.021

Lipoprotein (a), mg/L

92.0(47.0,190.0)

76.0(41.0,170.0)

68.0(33.0,147.0)

< 0.001

85.0(45.0,180.5)

83.0(41.0,174.5)

72.0(38.0,151.0)

< 0.001