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Table 1 Sample characteristics of Chinese adults aged ≥55 years old at the first cognitive function test by quartiles of iron related dietary pattern (N = 4685)

From: Iron-related dietary pattern increases the risk of poor cognition

  Q1 Q2 Q3 Q4 p-value
N = 1150 N = 1128 N = 1161 N = 1246  
Energy intake (kcal/d) 1625.8 (440.6) 2028.5 (1057.2) 2196.2 (552.1) 2516.4 (799.3) < 0.001
Fat intake (g/d) 56.5 (30.3) 71.0 (112.6) 70.7 (36.2) 72.8 (58.6) < 0.001
Protein intake (g/d) 47.1 (14.6) 60.0 (17.2) 67.1 (20.5) 78.4 (28.5) < 0.001
Carbohydrate intake (g/d) 229.1 (69.9) 282.3 (80.1) 316.2 (88.9) 377.5 (121.5) < 0.001
Most recent iron intake (mg/d) 13.8 (7.2) 18.1 (7.3) 21.2 (11.0) 26.8 (15.2) < 0.001
Cumulative iron intake (mg/d) 15.8 (6.2) 21.2 (6.6) 24.5 (9.4) 31.0 (12.2) < 0.001
Intake of fruit (g/d) 22.6 (69.4) 23.8 (73.8) 23.9 (83.9) 22.7 (90.2) 0.97
Intake of fresh vegetable (g/d) 183.8 (103.5) 254.4 (132.4) 298.4 (155.6) 352.3 (234.9) < 0.001
Intake of rice (g/d) 190.9 (116.7) 232.1 (140.5) 252.9 (163.5) 237.7 (207.9) < 0.001
Intake of wheat (g/d) 84.4 (90.9) 107.9 (110.8) 140.3 (138.3) 227.8 (226.3) < 0.001
Intake of meat (g/d) 56.0 (58.1) 77.8 (74.4) 80.6 (83.4) 77.1 (102.3) < 0.001
Age (years) 67.8 (9.0) 63.1 (7.3) 62.0 (6.8) 60.9 (6.1) < 0.001
Sex      < 0.001
 Men 356 (31.0%) 499 (44.2%) 594 (51.2%) 799 (64.1%)  
 Women 794 (69.0%) 629 (55.8%) 567 (48.8%) 447 (35.9%)  
Education      0.002
 Low 727 (77.5%) 735 (70.7%) 773 (71.8%) 832 (70.7%)  
 Medium 105 (11.2%) 158 (15.2%) 163 (15.1%) 202 (17.2%)  
 High 106 (11.3%) 146 (14.1%) 141 (13.1%) 142 (12.1%)  
Urbanization      < 0.001
 Low 224 (19.5%) 218 (19.3%) 282 (24.3%) 468 (37.6%)  
 Medium 274 (23.8%) 325 (28.8%) 368 (31.7%) 352 (28.3%)  
 High 652 (56.7%) 585 (51.9%) 511 (44.0%) 426 (34.2%)  
Smoking      < 0.001
 Non-smoker 879 (76.8%) 796 (70.7%) 765 (65.9%) 709 (57.0%)  
 Ex-smokers 42 (3.7%) 33 (2.9%) 36 (3.1%) 66 (5.3%)  
 Current smokers 224 (19.6%) 297 (26.4%) 359 (30.9%) 469 (37.7%)  
Survey year      < 0.001
 1997 561 (48.8%) 537 (47.6%) 500 (43.1%) 514 (41.3%)  
 2000 210 (18.3%) 171 (15.2%) 186 (16.0%) 207 (16.6%)  
 2004 246 (21.4%) 239 (21.2%) 284 (24.5%) 324 (26.0%)  
 2006 133 (11.6%) 181 (16.0%) 191 (16.5%) 201 (16.1%)  
Alcohol drinking (yes) 241 (21.4%) 305 (27.6%) 390 (34.0%) 498 (40.7%) < 0.001
Physical activity (MET, hours/week) 58.1 (75.9) 87.2 (101.0) 91.3 (98.8) 111.9 (109.5) < 0.001
BMI (kg/m2) 22.8 (3.8) 23.2 (3.7) 23.1 (3.5) 23.1 (3.4) 0.075
BMI ≥ 24 kg/m2 367 (34.9%) 408 (39.2%) 412 (37.9%) 407 (35.8%) 0.15
Hypertension (yes) 447 (41.2%) 375 (35.5%) 363 (32.8%) 375 (32.3%) < 0.001
Diabetes (yes) 45 (4.0%) 36 (3.2%) 29 (2.6%) 39 (3.2%) 0.29
Stroke (yes) 34 (3.0%) 19 (1.7%) 18 (1.6%) 28 (2.3%) 0.082
  1. Data are shown as n (%) or mean ± SD. p values were calculated from ANOVA or chi square test