TABLE 2.
Serum metabolites associated with self-reported total coffee intake in a nested case-control study within the PLCO Cancer Screening Trial (n = 498 participants)1
| Mean percentile of metabolite distribution by level of coffee intake2 |
||||||
| Serum metabolite | None (n = 54) | Low (n = 236) | High (n = 208) | Participants with metabolites below the LLOD, n (%) | Partial correlation coefficient | P |
| Cases/controls, n | 26/28 | 118/118 | 107/101 | — | — | — |
| Trigonelline (N′-methylnicotinate) | 17.0 | 44.2 | 65.0 | 111 (22) | 0.608 | 4.26 × 10−51 |
| Quinate | 17.7 | 44.2 | 64.7 | 95 (19) | 0.585 | 1.62 × 10−46 |
| X_12039 | 22.7 | 44.2 | 63.4 | 175 (35) | 0.507 | 1.26 × 10−33 |
| X_13741 | 26.5 | 43.1 | 63.7 | 169 (34) | 0.455 | 1.42 × 10−26 |
| X_12816 | 23.8 | 43.0 | 64.5 | 231 (46) | 0.452 | 3.47 × 10−26 |
| X_14465 | 22.1 | 44.0 | 63.9 | 99 (20) | 0.451 | 4.87 × 10−26 |
| X_14473 | 22.1 | 44.3 | 63.9 | 99 (20) | 0.451 | 4.87 × 10−26 |
| X_17185 | 27.0 | 43.3 | 63.4 | 199 (40) | 0.429 | 1.84 × 10−23 |
| X_12230 | 25.3 | 44.3 | 62.6 | 195 (39) | 0.423 | 8.61 × 10−23 |
| Paraxanthine | 30.8 | 42.7 | 63.0 | 29 (6) | 0.383 | 1.12 × 10−18 |
| N-(2-furoyl)glycine | 27.0 | 46.1 | 60.2 | 209 (42) | 0.355 | 4.22 × 10−16 |
| Catechol sulfate | 28.3 | 44.7 | 61.4 | 3 (1) | 0.352 | 7.51 × 10−16 |
| Caffeine | 32.6 | 45.1 | 59.8 | 19 (4) | 0.327 | 1.02 × 10−13 |
| X_05426 | 29.3 | 44.2 | 61.7 | 21 (4) | 0.324 | 1.6 × 10−13 |
| 1-Methylxanthine | 33.8 | 44.2 | 60.6 | 194 (39) | 0.315 | 7.7 × 10−13 |
| Theophylline | 32.9 | 44.4 | 60.6 | 61 (12) | 0.306 | 4.06 × 10−12 |
| X_12329 | 34.6 | 45.8 | 58.5 | 321 (65) | 0.302 | 7.22 × 10−12 |
| 1,3,7-Trimethylurate | 37.2 | 45.1 | 58.7 | 284 (57) | 0.266 | 2.03 × 10−9 |
| 3-Hydroxyhippurate | 35.3 | 48.9 | 55.0 | 292 (59) | 0.221 | 7.04 × 10−7 |
| 1,7-Dimethylurate | 40.3 | 44.9 | 58.1 | 227 (46) | 0.219 | 9.52 × 10−7 |
| 1-Methylurate | 40.7 | 43.8 | 59.4 | 264 (53) | 0.210 | 2.7 × 10−6 |
| X_14291 | 32.6 | 46.4 | 58.3 | 99 (20) | 0.202 | 6.13 × 10−6 |
| X_14374 | 36.6 | 46.3 | 57.4 | 15 (3) | 0.202 | 6.5 × 10−6 |
| Cyclo(leu-pro) | 35.0 | 48.4 | 55.5 | 257 (52) | 0.199 | 8.14 × 10−6 |
| 4-Vinylphenol sulfate | 34.5 | 46.1 | 58.2 | 34 (7) | 0.188 | 2.65 × 10−5 |
| 3-(3-Hydroxyphenyl) propionate | 43.2 | 49.7 | 52.1 | 430 (86) | 0.183 | 4.27 × 10−5 |
| Theobromine | 46.1 | 45.8 | 55.6 | 20 (4) | 0.182 | 4.61 × 10−5 |
| X_12734 | 37.4 | 46.1 | 57.6 | 254 (51) | 0.179 | 6.16 × 10−5 |
| Cinnamoylglycine | 41.9 | 50.4 | 51.4 | 335 (67) | 0.178 | 7.37 × 10−5 |
Only significant associations from the linear regression of ln(metabolite) on ln(coffee) are shown; self-reported coffee intake was reported at baseline on the baseline food-frequency questionnaire; metabolites with the prefix X_ are of unknown identity. Partial correlations were determined between ln(metabolite) and ln(coffee) adjusted for sex, tobacco smoking status (current, former, and never), age (continuous), and BMI (continuous). P values are from the linear regression of ln(metabolite) on ln(coffee) adjusted for sex, tobacco smoking status (current, former, and never), age (continuous), and BMI (continuous). Bonferroni-corrected level of significance, P < 7.61 × 10−5. LLOD, lower limit of detection; PLCO, Prostate, Lung, Colorectal, and Ovarian.
Average percentile of overall metabolite distribution represented by each category of coffee consumption; the average percentile was calculated by assigning a ranking for each participant for each metabolite of interest and dividing by the total number of individuals to convert the ranking into a percentile; within each category of coffee intake, percentiles were averaged for a given metabolite to calculate an average percentile. None, low, and high coffee intakes were defined as 0, <2.5, and ≥2.5 cups/d, respectively.