TABLE 3.
Incident colorectal adenoma risk of dietary fiber intake
| Any incident distal colon or rectal adenoma |
Distal colon adenoma1 |
Rectal adenoma1 |
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| Tertile2 | Noncases (n = 15,976) | Cases (n = 1004) | Base model3 OR (95% CI) | Adjusted4 OR (95% CI) | Cases (n = 770) | Adjusted4 OR (95% CI) | Cases(n = 262) | Adjusted4 OR (95% CI) |
| Total fiber | ||||||||
| <9.9 (8.4) g/1000 kcal | 4793 | 394 | 1.00 | 1.00 | 298 | 1.00 | 106 | 1.00 |
| ≥9.9 to <12.8 (11.3) g/1000 kcal | 5496 | 340 | 0.81 (0.69, 0.94) | 0.88 (0.75, 1.04) | 266 | 0.91 (0.76, 1.09) | 87 | 0.80 (0.59, 1.09) |
| ≥12.8 (15.0) g/1000 kcal | 5687 | 270 | 0.65 (0.54, 0.77) | 0.76 (0.63, 0.91) | 206 | 0.75 (0.61, 0.92) | 69 | 0.68 (0.48, 0.96) |
| P-trend | <0.001 | 0.003 | 0.006 | 0.03 | ||||
| Cereal/grain fiber | ||||||||
| <3.0 (2.4) g/1000 kcal | 4898 | 382 | 1.00 | 1.00 | 296 | 1.00 | 94 | 1.00 |
| ≥3.0 to <4.3 (3.6) g/1000 kcal | 5380 | 317 | 0.75 (0.64, 0.87) | 0.80 (0.68, 0.94) | 240 | 0.77 (0.65, 0.92) | 85 | 0.86 (0.64, 1.17) |
| ≥4.3 (5.4) g/1000 kcal | 5698 | 305 | 0.70 (0.59, 0.81) | 0.78 (0.66, 0.92) | 234 | 0.76 (0.63, 0.91) | 83 | 0.86 (0.63, 1.18) |
| P-trend | <0.001 | 0.006 | 0.007 | 0.39 | ||||
| Vegetable fiber | ||||||||
| <3.6 (2.9) g/1000 kcal | 5086 | 353 | 1.00 | 1.00 | 272 | 1.00 | 91 | 1.00 |
| ≥3.6 to <5.1 (4.3) g/1000 kcal | 5375 | 372 | 1.05 (0.90, 1.23) | 1.10 (0.94, 1.28) | 286 | 1.09 (0.91, 1.30) | 97 | 1.10 (0.82, 1.47) |
| ≥5.1 (6.4) g/1000 kcal | 5515 | 279 | 0.83 (0.70, 0.98) | 0.90 (0.76, 1.08) | 212 | 0.88 (0.72, 1.07) | 74 | 0.91 (0.65, 1.27) |
| P-trend | 0.02 | 0.22 | 0.18 | 0.54 | ||||
| Fruit fiber | ||||||||
| <1.5 (1.0) g/1000 kcal | 4873 | 409 | 1.00 | 1.00 | 319 | 1.00 | 105 | 1.00 |
| ≥1.5 to <2.8 (2.2) g/1000 kcal | 5487 | 306 | 0.73 (0.62, 0.85) | 0.80 (0.68, 0.94) | 228 | 0.76 (0.63, 0.91) | 85 | 0.84 (0.62, 1.13) |
| ≥2.8 (3.9) g/1000 kcal | 5616 | 289 | 0.72 (0.61, 0.85) | 0.85 (0.71, 1.01) | 223 | 0.82 (0.67, 1.00) | 72 | 0.78 (0.55, 1.10) |
| P-trend | <0.001 | 0.09 | 0.07 | 0.17 | ||||
| Legume fiber | ||||||||
| <1.0 (0.7) g/1000 kcal | 5057 | 329 | 1.00 | 1.00 | 245 | 1.00 | 90 | 1.00 |
| ≥1.0 to <1.5 (1.2) g/1000 kcal | 5392 | 344 | 0.98 (0.84, 1.15) | 1.02 (0.87, 1.19) | 259 | 1.03 (0.86, 1.24) | 96 | 1.03 (0.77, 1.38) |
| ≥1.5 (2.1) g/1000 kcal | 5527 | 331 | 0.88 (0.75, 1.03) | 0.93 (0.79, 1.10) | 266 | 1.01 (0.84, 1.22) | 76 | 0.77 (0.56, 1.06) |
| P-trend | 0.09 | 0.35 | 0.94 | 0.09 | ||||
Includes 52 patients who had adenomas in both the descending/sigmoid colon and rectum.
Values in parentheses in this column are median intakes.
The ORs and 95% CIs were calculated by using unconditional logistic regression. The base models adjusted for age at the year 3 or 5 screen (y), study center (10 centers), sex, ethnicity (non-Hispanic white, non-Hispanic black, Asian, other), total energy intake (kcal/d), and energy by using the nutrient-density method [fiber (g/1000 kcal)].
The fully adjusted model was additionally adjusted for smoking status (never, former, current, or pipe or cigar smoker only), alcohol intake (<0.5, 0.5 to <5, or ≥5 g/1000 kcal), and total folate intake from diet (prefortification) and supplements (μg/d). Other confounders tested but that did not change the β coefficient by ≥10% included education (<high school, completed high school, some college, or college graduate or postgraduate), family history of colorectal cancer (yes, no, or unknown), BMI (in kg/m2; ≤25, 25 to <30, ≥30, or unknown), regular nonsteroidal anti-inflammatory drug use (yes, no, or unknown), hormone replacement therapy use (current, former, never, or unknown), exercise per week (<1 h, 1–3 h, ≥4 h, or unknown), dietary calcium intake (g/1000 kcal/d), supplemental calcium intake (mg/d), processed meat intake (g/1000 kcal/d), and red meat intake (g/1000 kcal/d).