Table 2.

Population characteristics according to quartiles of heme iron intake in the E3N study

Total heme iron intake (mg/day)a
CharacteristicsTotal<0.750.75–<1.071.07–<1.45≥1.45
Number17,3974,3524,3504,3454,350
Number of cases1,409309351382367
Age at baseline (y)b53.2 ± 6.654.1 ± 6.853.8 ± 6.653.0 ± 6.552.1 ± 6.1
Age at diagnosis (y)b58.7 ± 6.859.9 ± 7.159.2 ± 6.858.7 ± 7.057.3 ± 6.2
Heme iron intake (mg/day)b
 Total1.14 ± 0.550.51 ± 0.170.91 ± 0.0941.25 ± 0.111.88 ± 0.41
 Nonnitrosylated0.97 ± 0.480.44 ± 0.160.78 ± 0.121.07 ± 0.141.60 ± 0.39
 Nitrosylated0.16 ± 0.140.073 ± 0.060.13 ± 0.090.17 ± 0.110.28 ± 0.17
Red meat intake (g/day)b
 Total86.7 ± 43.140.5 ± 16.870.4 ± 15.095.2 ± 16.7140.6 ± 35.4
 Nonprocessed55.1 ± 31.523.1 ± 12.244.0 ± 13.161.4 ± 15.592.0 ± 29.1
 Processed31.6 ± 23.717.5 ± 13.326.4 ± 17.033.8 ± 19.948.6 ± 29.4
Other dietary intakeb
 Total iron (mg/day)14.5 ± 4.812.6 ± 4.713.6 ± 4.214.9 ± 4.417.1 ± 4.7
 Nonheme iron (mg/day)13.4 ± 4.612.1± 4.612.7 ± 4.213.7 ± 4.415.2 ± 4.6
 FRAP (mmol/day)13.5 ± 5.612.5 ± 5.313.0 ± 5.413.7± 5.514.9 ± 6.0
 TRAP (mmol/day)4.97 ± 2.44.62 ± 2.34.79 ± 2.35.03 ± 2.45.43 ± 2.6
 Fibers (g/day)25.2 ± 7.824.3 ± 8.324.5 ± 7.425.4 ± 7.526.7 ± 7.7
 Fruits and vegetables (g/day)535 ± 242530 ± 253525 ± 236532 ± 231552 ± 245
 Calcium (mg/day)1,081 ± 3751,049 ± 3851,045 ± 3621,082 ± 3641,146 ± 381
 Total energy intake (kcal/day)b2,222 ± 5701,938 ± 4972,105 ± 4912,285 ± 5132,561 ± 577
 Physical activity (METs-h/week)b40.7 ± 26.241.8 ± 26.440.9 ± 26.440.2 ± 25.640.0 ± 26.2
 BMI (kg/m2)b22.8 ± 3.222.0 ± 2.922.6 ± 3.023.0 ± 3.223.7 ± 3.6
 Alcohol consumption (g/day)b11.4 ± 13.88.2 ± 11.310.0 ± 11.911.9 ± 13.415.5 ± 16.8
 Ratio heme iron/FRAP (g/mol)0.097 ± 0.060.037 ± 0.010.070 ± 0.0080.10 ± 0.010.18 ± 0.07
 Ratio heme iron/TRAP (g/mol)0.28 ± 0.220.10 ± 0.030.19 ± 0.020.29 ± 0.040.55 ± 0.27
Smoking statusc
 Never smoker9,336 (53.7)2,410 (55.4)2,390 (54.9)2,383 (54.8)2,153 (49.5)
 Past or current smoker8,061 (46.3)1,942 (44.6)1,960 (45.1)1,962 (45.2)2,197 (50.5)
Number of years of educationc
 <14 years11,296 (64.9)2,914 (67.0)2,809 (64.6)2,761 (63.5)2,812 (64.6)
 >14 years6,101 (35.1)1,438 (33.0)1,541 (35.4)1,584 (36.5)1,538 (35.4)
Menopausal statusc
 Premenopausal7,086 (40.7)1,555 (35.7)1,687 (38.8)1,848 (42.5)1,996 (45.9)
 Postmenopausal10,311 (59.3)2,797 (64.3)2,663 (61.2)2,497 (57.5)2,354 (54.1)
Family history of colorectal cancerc
 No13,329 (76.6)3,386 (77.8)3,334 (76.6)3,336 (76.8)3,273 (75.2)
 Yes4,068 (23.4)966 (22.2)1,016 (23.4)1,009 (23.2)1,077 (24.8)

Abbreviation: MET, metabolic equivalent task.