Table 1.
Baseline characteristics of the UK Biobank cohort by quartiles of gluten intake (g/day) and sex
| Characteristics | All (n=39,927) | Male (n=17,851) | Female (n=22,076) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | ||
| Gluten intake (g/d) | 9.7 (6.2–13.7) | 5.8 (4.1–7.0) | 10.0 (9.1–10.8) | 13.7 (12.7–14.7) | 19.2 (17.4–22.5) | 3.4 (1.8–4.7) | 6.7 (6.0–7.4) | 9.8 (9.0–10.6) | 14.5 (12.8–17.0) |
| Energy-adjusted gluten intake (mg * kJ-1 * d-1) | 1.00 (0.67–1.38) | 0.57 (0.40–0.71) | 0.98 (0.84–1.12) | 1.28 (1.10–1.47) | 1.72 (1.44–2.03) | 0.40 (0.21–0.56) | 0.79 (0.66–0.92) | 1.12 (0.95–1.30) | 1.56 (1.31–1.86) |
| Gluten-free diet | 628 (1.6) | 67 (1.5) | 25 (0.6) | 20 (0.4) | 22 (0.5) | 299 (5.4) | 102 (1.8) | 50 (0.9) | 43 (0.8) |
| Age (years) | 57 (49–63) | 60 (51–64) | 59 (51–64) | 58 (50–63) | 56 (48–62) | 58 (50–63) | 58 (50–63) | 56 (49–62) | 55 (47–62) |
| Smoking status | |||||||||
| Never | 22,992 (57.6) | 2250 (50.4) | 2244 (50.3) | 2299 (51.5) | 2376 (53.2) | 3353 (60.8) | 3433 (62.2) | 3495 (63.3) | 3542 (64.2) |
| Previous | 13,532 (33.9) | 1781 (39.9) | 1746 (39.1) | 1700 (38.1) | 1608 (36.0) | 1777 (32.2) | 1686 (30.5) | 1645 (29.8) | 1589 (28.8) |
| Current | 3313 (8.3) | 425 (9.5) | 461 (10.3) | 455 (10.2) | 66 (10.4) | 76 (6.8) | 386 (7.0) | 367 (6.6) | 377 (6.8) |
| Pnta | 90 (0.2) | 7 (0.2) | 12 (0.3) | 9 (0.2) | 12 (0.3) | 13 (0.2) | 14 (0.3) | 12 (0.2) | 11 (0.2) |
| Ethnic background | |||||||||
| White | 37,718 (94.5) | 4179 (93.6) | 4285 (96.0) | 4305 (96.5) | 4223 (94.6) | 5115 (92.7) | 5205 (94.3) | 5220 (94.6) | 5186 (94.0) |
| Black | 554 (1.4) | 64 (1.4) | 40 (0.9) | 26 (0.6) | 51 (1.1) | 113 (2.0) | 91 (1.6) | 78 (1.4) | 91 (1.6) |
| Asian | 893 (2.2) | 133 (3.0) | 71 (1.6) | 68 (1.5) | 114 (2.6) | 157 (2.8) | 108 (2.0) | 102 (1.8) | 140 (2.5) |
| Mixed | 296 (0.7) | 32 (0.7) | 25 (0.6) | 19 (0.4) | 27 (0.6) | 54 (1.0) | 50 (0.9) | 46 (0.8) | 43 (0.8) |
| Other | 306 (0.8) | 28 (0.6) | 17 (0.4) | 28 (0.6) | 28 (0.6) | 60 (1.1) | 44 (0.8) | 55 (1.0) | 46 (0.8) |
| Pnta or Dnk | 160 (0.4) | 27 (0.6) | 25 (0.6) | 17 (0.4) | 19 (0.4) | 20 (0.4) | 21 (0.4) | 18 (0.3) | 13 (0.2) |
| Qualifications | |||||||||
| Noa | 3444 (8.6) | 392 (8.8) | 387 (8.7) | 423 (9.5) | 417 (9.3) | 415 (7.5) | 469 (8.5) | 476 (8.6) | 465 (8.4) |
| Other | 1924 (4.8) | 178 (4.0) | 189 (4.2) | 175 (3.9) | 168 (3.8) | 329 (6.0) | 296 (5.4) | 320 (5.8) | 269 (4.9) |
| NVQ or HND or HNC equivalent | 2067 (5.2) | 330 (7.4) | 340 (7.6) | 328 (7.3) | 346 (7.8) | 165 (3.0) | 160 (2.9) | 189 (3.4) | 209 (3.8) |
| CSEs or equivalent | 1843 (4.6) | 164 (3.7) | 193 (4.3) | 233 (5.2) | 257 (5.8) | 233 (4.2) | 228 (4.1) | 246 (4.5) | 289 (5.2) |
| O levels/GCSEs or equivalent | 8515 (21.3) | 790 (17.7) | 815 (18.3) | 872 (19.5) | 905 (20.3) | 1266 (22.9) | 1323 (24.0) | 1287 (23.3) | 1257 (22.8) |
| A levels/AS levels or equivalent | 5267 (13.2) | 527 (11.8) | 552 (12.4) | 526 (11.8) | 533 (11.9) | 817 (14.8) | 777 (14.1) | 775 (14.0) | 760 (13.8) |
| College or university degree | 16,640 (41.7) | 2053 (46.0) | 1961 (43.9) | 1882 (42.2) | 1811 (40.6) | 2260 (40.9) | 2235 (40.5) | 2195 (39.8) | 2243 (40.6) |
| Pnta | 227 (0.6) | 29 (0.6) | 26 (0.6) | 24 (0.5) | 25 (0.6) | 34 (0.6) | 31 (0.6) | 31 (0.6) | 27 (0.5) |
| Total household income per year (£) | |||||||||
| <18000 | 5978 (15.0) | 548 (12.3) | 596 (13.4) | 647 (14.5) | 656 (14.7) | 768 (13.9) | 891 (16.1) | 876 (15.9) | 996 (18.0) |
| 18000–30999 | 8802 (22.0) | 940 (21.1) | 981 (22.0) | 987 (22.1) | 981 (22.0) | 1190 (21.6) | 1269 (23.0) | 1243 (22.5) | 1211 (21.9) |
| 31000–51999 | 9897 (24.8) | 1170 (26.2) | 1231 (27.6) | 1192 (26.7) | 1189 (26.6) | 1286 (23.3) | 1274 (23.1) | 1282 (23.2) | 1273 (23.1) |
| 52000–100000 | 8287 (20.8) | 1056 (23.7) | 1012 (22.7) | 1016 (22.8) | 1016 (22.8) | 1095 (19.8) | 1033 (18.7) | 1020 (18.5) | 1039 (18.8) |
| >100000 | 2608 (6.5) | 397 (8.9) | 319 (7.1) | 283 (6.3) | 267 (6.0) | 385 (7.0) | 309 (5.6) | 328 (5.9) | 320 (5.8) |
| Pnta or Dnk | 4355 (10.9) | 352 (7.9) | 324 (7.3) | 338 (7.6) | 353 (7.9) | 795 (14.4) | 743 (13.5) | 770 (14.0) | 680 (12.3) |
| Energy intake | |||||||||
| kJ/d | 9452 (8058–11207) | 9673 (8573–11048) | 10101 (8945–11635) | 10650 (9312–12322) | 11692 (10070–13688) | 7877 (6917–9127) | 8348 (7308–9725) | 8719 (7582–10248) | 9597 (8225–11358) |
| kcal/d | 2259 (1926–2678) | 2312 (2049–2641) | 2414 (2138–2781) | 2546 (2226–2945) | 2794 (2407–3272) | 1883 (1653–2181) | 1995 (1747–2324) | 2084 (1812–2449) | 2294 (1966–2715) |
| Carbohydrate intake (%Energy) | 48.2 (42.5–53.8) | 45.8 (39.2–51.7) | 46.4 (40.5–52.2) | 47.5 (42.1–52.8) | 49.6 (44.3–54.7) | 47.3 (40.9–53.7) | 48.7 (42.9–54.2) | 48.7 (43.6–53.9) | 50.5 (45.3–55.6) |
| Protein intake (%Energy) | 14.8 (12.6–17.2) | 14.7 (12.5–17.3) | 14.5 (12.5–16.8) | 14.2 (12.2–16.3) | 14.0 (12.1–16.2) | 15.8 (13.3–18.5) | 15.2 (12.8–17.6) | 14.9 (12.7–17.4) | 14.7 (12.5–17.1) |
| Fat intake (%Energy) | 31.7 (26.8–36.6) | 31.4 (26.3–36.5) | 31.9 (27.3–36.9) | 31.7 (27.0–36.3) | 31.0 (26.2–35.6) | 31.6 (26.2–37.1) | 32.0 (27.1–36.9) | 32.5 (27.6–37.2) | 31.5 (26.6–36.3) |
| Fiber intake (g/d) | 17.1 (13.0–22.0) | 15.6 (11.4–20.0) | 16.5 (12.5–21.3) | 18.4 (14.0–23.1) | 20.8 (16.1–26.4) | 15.1 (11.3–19.6) | 15.9 (12.2–20.3) | 16.9 (13.1–21.4) | 19.0 (14.8–24.1) |
| Total physical activity (MET-min/week) | 1911 (924–3672) | 1866 (933–3653) | 1884 (874–3652) | 1926 (924–3756) | 2026 (956–4040) | 1977 (956–3672) | 1890 (919–3546) | 1893 (914–3546) | 1866 (876–3590) |
| Percentage body fat | 29.8 (24.1–36.3) | 24.2 (20.5–27.6) | 24.1 (20.5–27.6) | 24.3 (20.6–27.9) | 24.2 (20.2–28.0) | 34.8 (30.2–39.2) | 35.3 (30.7–39.8) | 35.6 (30.8–40.1) | 35.7 (30.8–40.7) |
| WC (cm) | 87 (78–96) | 93 (87–100) | 93 (87–100) | 94 (88–101) | 95 (88–102) | 79 (73–87) | 80 (74–88) | 81 (74–89) | 82 (74–91) |
| WHR | 0.86 (0.79–0.93) | 0.92 (0.88–0.96) | 0.92 (0.88–0.96) | 0.93 (0.89–0.97) | 0.92 (0.88–0.97) | 0.80 (0.76–0.85) | 0.80 (0.76–0.85) | 0.80 (0.76–0.86) | 0.81 (0.76–0.86) |
| WHtR | 0.51 (0.47–0.56) | 0.53 (0.49–0.57) | 0.53 (0.49–0.57) | 0.53 (0.50–0.57) | 0.53 (0.49–0.58) | 0.49 (0.45–0.54) | 0.49 (0.45–0.54) | 0.49 (0.45–0.55) | 0.50 (0.45–0.56) |
| BMI (kg/m2) | 25.7 (23.4–28.6) | 26.2 (24.2–28.5) | 26.3 (24.2–28.7) | 26.6 (24.4–29.1) | 26.8 (24.4–29.4) | 24.7 (22.4–27.4) | 24.9 (22.7–28.0) | 25.2 (22.7–28.4) | 25.5 (22.8–29.2) |
| SBP (mmHg) | 137 (125–151) | 140 (129–154) | 140 (129–153) | 140 (129–153) | 139 (128–151) | 135 (122–149) | 134 (122–149) | 134 (122–150) | 134 (121–148) |
| DBP (mmHg) | 81 (74–88) | 83 (76–90) | 83 (76–90) | 83 (76–90) | 82 (76–90) | 79 (72–87) | 79 (73–87) | 79 (73–87) | 79 (73–87) |
| HbA1c (mmol/mol) | 35.0 (32.6–37.5) | 35.0 (32.6–37.4) | 35.0 (32.8–37.4) | 35.0 (32.6–37.7) | 35.0 (32.6–37.6) | 34.9 (32.5–37.3) | 35.1 (32.7–37.5) | 35.1 (32.7–37.4) | 35.1 (32.6–37.5) |
| Total cholesterol | |||||||||
| mmol/l | 5.7 (5.0–6.4) | 5.6 (4.9–6.3) | 5.5 (4.8–6.3) | 5.5 (4.8–6.2) | 5.5 (4.8–6.2) | 5.9 (5.2–6.7) | 5.9 (5.2–6.7) | 5.8 (5.1–6.5) | 5.7 (5.0–6.5) |
| mg/dl | 220 (192–249) | 215 (188–242) | 214 (187–243) | 213 (184–241) | 211 (184–239) | 229 (201–257) | 228 (201–258) | 225 (199–253) | 221 (194–250) |
| LDL cholesterol | |||||||||
| mmol/l | 3.5 (3.0–4.1) | 3.5 (3.0–4.1) | 3.5 (2.9–4.1) | 3.5 (2.9–4.1) | 3.5 (2.9–4.0) | 3.6 (3.0–4.2) | 3.6 (3.1–4.2) | 3.6 (3.0–4.1) | 3.5 (3.0–4.1) |
| mg/dl | 136 (115–159) | 136 (114–157) | 135 (114–158) | 135 (113–157) | 133 (112–156) | 138 (117–161) | 140 (118–162) | 137 (117–159) | 135 (114–159) |
| HDL cholesterol | |||||||||
| mmol/l | 1.5 (1.2–1.7) | 1.3 (1.1–1.5) | 1.3 (1.1–1.5) | 1.3 (1.1–1.5) | 1.3 (1.1–1.5) | 1.7 (1.4–1.9) | 1.6 (1.4–1.9) | 1.6 (1.4–1.9) | 1.6 (1.3–1.8) |
| mg/dl | 56 (47–67) | 51 (44–60) | 50 (43–59) | 49 (42–58) | 49 (42–57) | 64 (55–75) | 63 (54–73) | 62 (53–72) | 61 (52–71) |
| Triglyceride | |||||||||
| mmol/l | 1.4 (1.0–2.0) | 1.5 (1.1–2.2) | 1.6 (1.1–2.3) | 1.7 (1.2–2.4) | 1.6 (1.1–2.4) | 1.2 (0.9–1.7) | 1.3 (0.9–1.8) | 1.3 (0.9–1.8) | 1.3 (0.9–1.9) |
| mg/dl | 123 (87–178) | 135 (96–196) | 142 (99–203) | 145 (101–211) | 144 (100–208) | 106 (78–148) | 111 (81–155) | 113 (82–159) | 113 (83–162) |
| CRP (mg/dl) | 1.1 (0.6–2.3) | 1.1 (0.6–2.1) | 1.1 (0.6–2.1) | 1.1 (0.6–2.1) | 1.1 (0.6–2.1) | 1.1 (0.5–2.2) | 1.1 (0.5–2.3) | 1.2 (0.6–2.4) | 1.2 (0.6–2.7) |
| GFR (ml/min) | 106 (95–116) | 99 (89–108) | 99 (89–108) | 99 (89–108) | 100 (90–110) | 112 (102–121) | 111 (101–120) | 111 (101–120) | 113 (102–122) |
Categorical variables are presented as number (percentage) and continuous variables as median (Q1–Q3). BMI body mass index, CRP C-reactive protein, CSE Certificate of Secondary Education, DBP diastolic blood pressure, Dnk do not know, GCSE General Certificate of Secondary Education, GFR glomerular filtration rate, HbA1c hemoglobin A1c, HDL high-density lipoprotein, HNC Higher National Certificate, HND Higher National Diploma, LDL low-density lipoprotein, MET metabolic equivalent of task, Noa none of the above, NVQ National Vocational Qualification Pnta prefer not to answer, Q quartile, SBP systolic blood pressure, WC waist circumference, WHR waist-to-hip ratio, WHtR waist-to-height ratio