TABLE 1.
Sample characteristics of Chinese adults aged ≥55 y attending the first cognitive function test by quartiles of cumulative iron1
| Iron intake quartiles | |||||
|---|---|---|---|---|---|
| 1 (median: 14.6 mg/d) (n = 1205) | 2 (19.3 mg/d) (n = 1081) | 3 (23.7 mg/d) (n = 1171) | 4 (31.7 mg/d) (n = 1228) | P | |
| Age, y | 66.5 ± 8.7 | 63.6 ± 7.7 | 62.0 ± 7.0 | 61.7 ± 6.5 | <0.001 |
| Sex, n (%) | <0.001 | ||||
| Men | 412 (34.2) | 519 (48.0) | 594 (50.7) | 723 (58.9) | |
| Women | 793 (65.8) | 562 (52.0) | 577 (49.3) | 505 (41.1) | |
| Education, n (%) | <0.001 | ||||
| Low | 759 (75.8) | 690 (70.5) | 755 (69.5) | 863 (74.1) | |
| Medium | 117 (11.7) | 136 (13.9) | 194 (17.9) | 181 (15.5) | |
| High | 125 (12.5) | 153 (15.6) | 137 (12.6) | 120 (10.3) | |
| Urbanization, n (%) | <0.001 | ||||
| Low | 216 (17.9) | 217 (20.1) | 303 (25.9) | 456 (37.1) | |
| Medium | 306 (25.4) | 308 (28.5) | 329 (28.1) | 376 (30.6) | |
| High | 683 (56.7) | 556 (51.4) | 539 (46.0) | 396 (32.2) | |
| Smoking, n (%) | <0.001 | ||||
| Nonsmoker | 898 (74.9) | 753 (69.7) | 760 (65.0) | 738 (60.1) | |
| Ex-smoker | 45 (3.8) | 39 (3.6) | 42 (3.6) | 51 (4.2) | |
| Current smoker | 256 (21.4) | 288 (26.7) | 367 (31.4) | 438 (35.7) | |
| Survey year, n (%) | 0.007 | ||||
| 1997 | 536 (44.5) | 521 (48.2) | 476 (40.6) | 579 (47.1) | |
| 2000 | 187 (15.5) | 161 (14.9) | 208 (17.8) | 218 (17.8) | |
| 2004 | 298 (24.7) | 235 (21.7) | 292 (24.9) | 268 (21.8) | |
| 2006 | 184 (15.3) | 164 (15.2) | 195 (16.7) | 163 (13.3) | |
| Alcohol drinking, n (%) | 273 (23.1) | 335 (31.4) | 387 (33.8) | 439 (36.4) | <0.001 |
| Physical activity, MET-h/wk | 64.2 ± 84.6 | 85.9 ± 97.5 | 94.2 ± 101.4 | 106.2 ± 107.4 | <0.001 |
| BMI, kg/m2 | 23.1 ± 3.8 | 23.2 ± 3.7 | 23.2 ± 3.6 | 22.8 ± 3.4 | 0.015 |
| BMI ≥24, n (%) | 429 (38.6) | 372 (37.2) | 431 (39.4) | 362 (32.6) | 0.004 |
| Energy intake, kcal/d | 1719.1 ± 503.8 | 2087.7 ± 1084.9 | 2180.8 ± 584.6 | 2413.0 ± 829.7 | <0.001 |
| Fat intake, g/d | 60.9 ± 34.9 | 70.0 ± 114.1 | 68.6 ± 36.5 | 72.2 ± 58.6 | <0.001 |
| Protein intake, g/d | 49.5 ± 15.8 | 62.6 ± 18.3 | 67.6 ± 21.3 | 74.2 ± 30.0 | <0.001 |
| Carbohydrate intake, g/d | 239.6 ± 75.0 | 295.4 ± 85.4 | 316.7 ± 99.1 | 358.9 ± 124.9 | <0.001 |
| Intake of fruit, g/d | 24.5 ± 73.5 | 25.8 ± 92.2 | 19.1 ± 70.1 | 23.7 ± 83.1 | 0.21 |
| Intake of fresh vegetable, g/d | 217.2 ± 137.1 | 268.4 ± 159.6 | 292.2 ± 192.8 | 317.4 ± 194.8 | <0.001 |
| Intake of meat, g/d | 62.2 ± 67.2 | 78.2 ± 80.9 | 79.5 ± 86.9 | 72.7 ± 90.8 | <0.001 |
| Most recent iron intake, mg/d | 13.2 ± 3.8 | 18.3 ± 5.2 | 21.1 ± 7.3 | 27.6 ± 18.4 | <0.001 |
| Cumulative iron intake, mg/d | 13.7 ± 2.6 | 19.2 ± 1.2 | 23.8 ± 1.6 | 35.9 ± 12.5 | <0.001 |
| Hypertension, n (%) | 468 (40.8) | 346 (34.1) | 370 (33.2) | 376 (33.2) | <0.001 |
| Diabetes, n (%) | 43 (3.6) | 27 (2.5) | 35 (3.0) | 44 (3.7) | 0.37 |
| Stroke, n (%) | 30 (2.5) | 19 (1.8) | 18 (1.6) | 32 (2.7) | 0.18 |
1
Values are means ± SDs unless otherwise indicated; n = 4685. P values were calculated by using ANOVA or chi-square test. MET-h, metabolic equivalent of task hours.