Table 3.
Characteristics of studies of fiber and CRC
| Study | Number of study participants | Age of participants | Follow-up years | CRC incidence | Analytic category | Analytical comparison, high versus low intake | Relative risk (95% CI) | Ref |
|---|---|---|---|---|---|---|---|---|
| 13 case-control studies | – | – | – | 5,225 (CRC), 10,349 (Control) | Total fiber | >31.2 g/day versus <10.1 g/day | CRC: 0.53 (0.47–0.61), p<0.0001 | Ref (51) |
| 16 case-control and 4 cohort studies | 10,948 men and women | – | – | – | Total fiber | per 100g increase | CRC: 0.72 (0.63–0.83) | Ref (53) |
| 25 prospective studies | – | – | – | – | Total fiber | – | CRC: 0.90 (0.86–0.94) | Ref (52) |
| EPIC | 142,250 men and 335,062 women | 35–70 | 1992–2002 | 2,869 (Colon), 1,266 (Rectum) | Total fiber | ≥28.5 g/day versus <16.4 g/day | CRC: 0.83 (0.72–0.96), p=0.013 | Ref (56) |
| Cereal fiber | ≥12.3 g/day versus <4.64 g/day | CRC: 0.87 (0.77–0.99), p=0.003 | ||||||
| EPIC | 131,985 men and 320,770 women | 35–70 | 1992–2002 | 2, 819 (CRC) | Total fiber | – | CRC: 0.86 (0.75–1.00), p=0.04 | Ref (55) |
| PLCO | 57,774 men and women | 55–74 | 1993–2001 | 733 (CRC) | Total fiber | ≥12.8 g/1000 kcal versus <9.9 g/1000 kcal | Distal colon cancer: 0.62 (0.41, 0.94), p=0.03 | Ref (57) |
| Case-control | – | 30–75 | – | 341 (Colon), 265 (Rectum), 613 (Control) | Total fiber | Men: >14.92 g/day versus <7.73 g/day | CRC: 0.38 (0.27–0.55), p<0.01 | Ref (60) |
| Women: >12.65 g/day versus <6.52 g/day | ||||||||
| JACC | 16,636 men and 26,479 women | 40–79 | 1988–1997 | 291 (Colon), 142 (Rectum) | Total fiber | – | CRC: 0.73 (0.51–1.03), p=0.028 | Ref (62) |
| NIH-AARP DHS | 291,988 men and 197,623 women | 50–71 | 1995–2000 | 2,974 (CRC) | Fiber from grains | >5.7 g/1000 kcal versus <1.7 g/1000 kcal | CRC: 0.86 (0.76–0.98), P=0.01 | Ref (65) |
| HELGA | 38,841 men and 69,159 women | 40–65 | 1991–2002 | 680 (Colon), 399 (Rectum) | Whole-grain wheat | Men: >9 g/day versus ≤1 g/day | CRC: 0.65 (0.50–0.84) | Ref (66) |
| Women: >36 g/day versus ≤3 g/day | ||||||||
| 13 prospective cohort studies | 725,628 men and women | – | 6 to 20 years | – | Total fiber | >30 g/day versus <10 g/day | non-significant associations | Ref (54) |
| HPFS and NHS | 47,279 men and 76,947 women | 40–75/30–55 | 1986–2010/1980–2010 | 1,202 (Colon), 310 (Rectum) | Total fiber | >14 g/1000 kcal versus <8 g/1000 kcal | non-significant associations | Ref (58) |
| WHS | 36,976 women | 45+ | 1993–2003 | 223 (CRC) | Total fiber | ≥23.1 g/day versus <12.5 g/day | non-significant associations | Ref (59) |
| SWHS | 73,314 women | 40–70 | 1997–2005 | 283 (CRC) | Total fiber | >13.45 g/day versus <7.3 g/day | non-significant associations | Ref (61) |
| JPHC | 65,803 men and 67,520 women | 45–74 | 1995–2006 | 742 (Colon) and 375 (Rectum) | Total fiber | Men: >18.7 g/day versus <6.4 g/day | non-significant associations | Ref (63) |
| Women: >20 g/day versus <8.3 g/day | ||||||||
| DCH | 26,630 men and 29,189 women | 50–64 | 1993–2009 | 461 (Colon), 283 (Rectum) | Total whole-grain | >160 g/dat versus ≤75 g/day | non-significant associations | Ref (68) |
| NOWAC | 78,254 women | 40–70 | 1996–2006 | 509 (Colon), 218 (Rectum) | whole-grain bread | 180–240 g/day versus 0 | non-significant associations | Ref (69) |