Table 1.
Characteristics of study participants aged ≥ 20 years from 1999 to 2004 National Health and Nutrition Examination Survey.
| Characteristics | Overall | Caffeine intake (mg/day) | P value | |||
|---|---|---|---|---|---|---|
| Group 1 | Group 2 | Group 3 | Group 4 | |||
| (≥ 0 to < 40 mg/day) | (≥ 40 to < 200 mg/day) | (≥ 200 to < 400 mg/day) | (≥ 400 mg/day) | |||
| Sample size, n (%) | 8993 (100) | 3038 (33.78) | 3446 (38.32) | 1644 (18.28) | 865 (9.62) | |
| Age, y, mean (SD) | 49.4 (18.8) | 47.9 (20.0) | 50.0 (19.4) | 50.5 (17.00) | 50.1 (14.8) | < 0.001 |
| Sex, n (%) | < 0.001 | |||||
| Male | 4234 | 1232 (40.55) | 1586 (46.02) | 876 (53.28) | 540 (62.43) | |
| Female | 4759 | 1806 (59.45) | 1860 (53.98) | 768 (46.72) | 325 (37.57) | |
| Educational level, n (%) | < 0.001 | |||||
| < High school | 3062 (34.12) | 1191 (39.32) | 1218 (35.42) | 451 (27.45) | 202 (23.41) | |
| Completed high school | 2071 (23.08) | 632 (20.86) | 785 (22.83) | 416 (25.32) | 238 (27.58) | |
| > High school | 3841 (42.80) | 1206 (39.82) | 1436 (41.76) | 776 (47.23) | 423 (49.02) | |
| Race/ethnicity, n (%) | < 0.001 | |||||
| Non-Hispanic White | 4390 (48.82) | 1085 (35.71) | 1611 (46.75) | 1030 (62.65) | 664 (76.76) | |
| Non-Hispanic Black | 1686 (18.75) | 830 (27.32) | 632 (18.34) | 168 (10.22) | 56 (6.47) | |
| Other | 2917 (32.44) | 1123 (36.97) | 1203 (34.91) | 446 (27.13) | 145 (16.67) | |
| Marital status, n (%) | < 0.001 | |||||
| Married/living with partner | 5351 (62.76) | 1666 (57.41) | 2054 (62.97) | 1047 (67.42) | 584 (72.19) | |
| Widowed/divorced/separated/never married | 3175 (37.24) | 1236 (42.59) | 1208 (37.03) | 506 (32.58) | 225 (27.81) | |
| PIR, n (%) | < 0.001 | |||||
| < 1.00 | 1502 (18.59) | 655 (24.34) | 572 (18.49) | 188 (12.47) | 87 (11.04) | |
| 1.00 to < 2.00 | 2098 (25.97) | 731 (27.16) | 867 (28.03) | 336 (22.28) | 164 (20.81) | |
| ≥ 2.00 | 4480 (5545) | 1305 (48.49) | 1654 (53.48) | 984 (65.25) | 537 (68.15) | |
| BMI category, n (%) | 0.024 | |||||
| < 25.0 kg/m2 | 2782 (31.97) | 975 (33.31) | 1018 (30.62) | 521 (32.56) | 268 (31.53) | |
| 25.0 to < 30.0 kg/m2 | 3169 (36.42) | 1071 (36.62) | 1213 (36.48) | 575 (35.94) | 309 (36.35) | |
| ≥ 30.0 kg/m2 | 2751 (31.61) | 880 (30.06) | 1094 (32.90) | 504 (31.50) | 273 (32.12) | |
| Smoking status, n (%) | < 0.001 | |||||
| Never smoking | 4688 (52.20) | 1913 (63.11) | 1833 (53.27) | 703 (42.79) | 239 (27.63) | |
| Former smoker | 2383 (26.54) | 656 (21.64) | 931 (27.06) | 515 (31.35) | 281 (32.49) | |
| Current smoker | 1909 (21.26) | 462 (15.24) | 677 (19.67) | 425 (25.87) | 345 (39.88) | |
| Alcohol status, n (%) | 5730 (66.95) | 1659 (58.03) | 2184 (66.81) | 1203 (75.76) | 684 (81.24) | < 0.001 |
| Cancer, n (%) | 756 (8.41) | 218 (7.19) | 321 (9.32) | 149 (9.07) | 68 (7.87) | 0.013 |
| Hypertension, n (%) | 3961 (44.05) | 1318 (43.38) | 1586 (46.02) | 711 (43.25) | 346 (40.00) | 0.007 |
| TG, mmol/L, mean (SD) | 5.20 (1.05) | 5.15 (1.05) | 5.21 (1.08) | 5.25 (1.01) | 5.23 (1.01) | 0.011 |
| Energy intake, kcal/day, mean (SD) | 2084.33 (1014.68) | 1941.82 (971.38) | 2036.96 (982.85) | 2242.28 (988.06) | 2473.39 (1187.85) | < 0.001 |
| Protein intake, g/day, mean (SD) | 78.69 (42.92) | 75.63 (43.52) | 76.67 (41.54) | 82.68 (41.83) | 89.93 (45.84) | < 0.001 |
| Calcium intake,mg/day, mean (SD) | 803.14 (580.56) | 788.32 (612.26) | 785.70 (562.78) | 826.30 (543.01) | 880.64 (598.01) | < 0.001 |
| Magnesium intake, mg/day, mean (SD) | 274.17 (148.27) | 265.21 (157.07) | 260.07 (137.19) | 287.91 (137.32) | 335.68 (161.12) | < 0.001 |
| Iron intake, mg/day, mean (SD) | 15.03 (9.43) | 14.75 (9.71) | 14.60 (9.10) | 15.52 (9.05) | 16.79 (10.16) | < 0.001 |
| Sodium intake, mg/day, mean (SD) | 3231.35 (1815.33) | 3013.37 (1759.74) | 3125.67 (1707.05) | 3510.66 (1861.69) | 3887.05 (2100.39) | < 0.001 |
SD standard deviation, PIR poverty-income ratio (ratio of family income to poverty threshold), BMI body mass index (calculated as weight in kilograms divided by the square of height in meters), TG triglycerides.