Table 1.
Based characteristics of all participants (n = 11,282).
| Characteristic | All | The Quintile of Dietary Vitamin C Intake (mg/day) | |||||
|---|---|---|---|---|---|---|---|
| Quintile 1 | Quintile 2 | Quintile 3 | Quintile 4 | Quintile 5 | p Value | ||
| Number of participants | 11,282 | 2250 | 2262 | 2254 | 2259 | 2257 | |
| Dietary vitamin C intake, mean (SD) | 81.00 (90.78) | 8.24 (5.06) | 26.40 (5.62) | 52.58 (9.73) | 97.31 (16.67) | 220.31 (109.64) | <0.001 |
| Serum Klotho concentration, pg/mL, median (25th–75th) |
800.55 (653.95, 990.00) |
787.50 (643.50, 973.72) |
797.85 (644.58, 989.98) |
802.30 (660.22, 994.20) |
794.20 (647.10, 981.90) |
821.70 (671.00, 1003.90) |
0.001 |
| Age, years, mean (SD) | 57.78 (10.81) | 56.52 (10.77) | 56.70 (10.59) | 58.24 (10.95) | 58.70 (10.90) | 57.75 (10.74) | <0.001 |
| Sex, n (%) | <0.001 | ||||||
| male | 5544 (49.10) | 1101 (48.9) | 1063 (47.0) | 1055 (46.8) | 1083 (47.9) | 1242 (55.0) | |
| female | 5738 (50.90) | 1149 (51.1) | 1199 (53.0) | 1199 (53.2) | 1176 (52.1) | 1015 (45.0) | |
| BMI, kg/m2, mean (SD) | 29.89 (6.74) | 30.35 (7.30) | 30.01 (6.62) | 29.95 (6.74) | 29.66 (6.51) | 29.46 (6.47) | <0.001 |
| Race/Ethnicity, n (%) | <0.001 | ||||||
| Non-Hispanic White | 5203 (46.10) | 1084 (48.2) | 1107 (48.9) | 1052 (46.7) | 1051 (46.5) | 909 (40.3) | |
| Non-Hispanic Black | 2234 (19.80) | 502 (22.3) | 423 (18.7) | 394 (17.5) | 425 (18.8) | 490 (21.7) | |
| Other Hispanic | 1199 (10.60) | 224 (10.0) | 225 (9.9) | 249 (11.0) | 228 (10.1) | 273 (12.1) | |
| Mexican American or Other | 2646 (23.5) | 440 (19.6) | 507 (22.4) | 559 (24.8) | 555 (24.6) | 585 (25.9) | |
| Educational attainment, n (%) | <0.001 | ||||||
| <High school | 2950 (26.10) | 745 (33.1) | 607 (26.8) | 583 (25.9) | 527 (23.3) | 488 (21.6) | |
| High school | 2519 (22.30) | 556 (24.7) | 582 (25.7) | 480 (21.3) | 476 (21.1) | 425 (18.8) | |
| College or above | 5813 (51.50) | 949 (42.2) | 1073 (47.4) | 1191 (52.8) | 1256 (55.6) | 1344 (59.5) | |
| PIR, mean (SD) | 2.65 (1.65) | 2.26 (1.54) | 2.56 (1.62) | 2.76 (1.66) | 2.85 (1.67) | 2.84 (1.69) | <0.001 |
| Serum cotinine, ng/mL, median (25–75th) | 0.04 (0.01, 2.54) | 0.13 (0.02, 187.75) | 0.05 (0.01, 64.12) | 0.03 (0.01, 0.36) | 0.03 (0.01, 0.23) | 0.03 (0.01, 0.20) | <0.001 |
| Alcohol consumption, n (%) | 0.138 | ||||||
| ≥12 drinks/year | 3199 (28.40) | 625 (27.8) | 655 (29.0) | 667 (29.6) | 655 (29.0) | 597 (26.5) | |
| <12 drinks/year | 8083 (71.60) | 1625 (72.2) | 1607 (71.0) | 1587 (70.4) | 1604 (71.0) | 1660 (73.5) | |
| Diabetes, n (%) | <0.001 | ||||||
| No | 8569 (76.00) | 1709 (76.0) | 1652 (73.0) | 1667 (74.0) | 1740 (77.0) | 1801 (79.8) | |
| Yes | 2713 (24.00) | 541 (24.0) | 610 (27.0) | 587 (26.0) | 519 (23.0) | 456 (20.2) | |
| Hypertension, n (%) | 0.230 | ||||||
| No | 5133 (45.50) | 989 (44.0) | 1010 (44.7) | 1027 (45.6) | 1044 (46.2) | 1063 (47.1) | |
| Yes | 6149 (54.50) | 1261 (56.0) | 1252 (55.3) | 1227 (54.4) | 1215 (53.8) | 1194 (52.9) | |
| eGFR, mL/min/1.73 m2, mean (SD) | 84.00 (19.64) | 83.94 (20.69) | 83.62 (20.10) | 84.26 (19.11) | 83.20 (19.77) | 84.96 (18.45) | 0.034 |
| Dietary energy intake, kcal/day, mean (SD) | 2023.66 (914.05) | 1747.34 (848.38) | 1941.31 (836.79) | 2045.95 (906.66) | 2072.94 (901.60) | 2310.06 (977.78) | <0.001 |
Note: SD: standard deviation; BMI: body mass index; PIR: family poverty income ratio; eGFR: estimated glomerular filtration rate. The quintile of dietary vitamin C consumption ranges: Quintile 1: 0 to 17.10 mg/day; Quintile 2: 17.11 to 36.80 mg/day; Quintile 3: 36.81 to 70.60 mg/day; Quintile 4: 70.61 to 129.78 mg/day; and Quintile 5: 129.79 to 1617.80 mg/day. Bold indicates significance with p < 0.05.