TABLE 2.
Age-standardized baseline characteristics by quintile of caffeine intake: Nurses’ Health Study I1
| Caffeine intake quintile |
|||||
| First (n = 16,801) | Second (n = 16,963) | Third (n = 17,092) | Fourth (n = 17,058) | Fifth (n = 17,055) | |
| Caffeine, mg/d | 54 ± 422 | 210 ± 60 | 367 ± 27 | 521 ± 120 | 802 ± 101 |
| Age,3 y | 52 ± 7 | 52 ± 7 | 53 ± 7 | 53 ± 7 | 52 ± 7 |
| BMI (kg/m2), % | |||||
| <20.0 | 10 | 10 | 10 | 9 | 10 |
| 20.0–24.9 | 45 | 45 | 49 | 47 | 47 |
| 25.0–29.9 | 28 | 28 | 28 | 30 | 31 |
| ≥30.0 | 16 | 15 | 12 | 14 | 12 |
| Thiazide use, % | 13 | 14 | 12 | 12 | 10 |
| Calcium supplement use, % | 56 | 54 | 53 | 52 | 48 |
| Calcium, mg/d | 721 ± 407 | 702 ± 392 | 716 ± 351 | 708 ± 368 | 696 ± 344 |
| Potassium, g/d | 2.4 ± 0.9 | 2.5 ± 0.9 | 2.7 ± 0.8 | 2.8 ± 0.9 | 3.0 ± 0.8 |
| Magnesium, mg/d | 257 ± 95 | 269 ± 95 | 288 ± 84 | 298 ± 97 | 316 ± 87 |
| Vitamin C, mg/d | 350 ± 635 | 309 ± 469 | 283 ± 466 | 271 ± 434 | 255 ± 428 |
| Total fructose, g/d | 23 ± 14 | 23 ± 16 | 20 ± 12 | 21 ± 14 | 18 ± 13 |
| Oxalate, mg/d | 326 ± 347 | 335 ± 346 | 329 ± 326 | 333 ± 341 | 317 ± 335 |
| Phytate, mg/d | 816 ± 419 | 789 ± 353 | 798 ± 365 | 747 ± 311 | 709 ± 315 |
| Alcohol intake, g/d | 4.9 ± 9.5 | 5.7 ± 10.2 | 7.7 ± 11.5 | 6.8 ± 10.6 | 6.6 ± 10.5 |
| Fluid intake, L/d | 0.8 ± 0.5 | 1.2 ± 0.5 | 1.3 ± 0.5 | 1.7 ± 0.5 | 2.0 ± 0.6 |
1
Values are standardized to the age distribution of the study population unless otherwise indicated. Values of categorical variables may not sum to 100% because of rounding.
2
Mean ± SD (all such values).
3
Values are not age adjusted.