Fiber and colon cancer

Does a diet high in fiber lower the risk of colon cancer?

Pawel Malczewski
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Short summary

A number of case-control studies and a large prospective study have shown that higher fiber intake lowers the incidence of colorectal cancer (including colon and rectal cancer). However, some other high quality studies (such as controlled clinical and intervention trials) showed no correlation. More high quality studies are needed, possibly using a higher amount of fiber or testing with various types of fiber. (1)Oregon State University. Micronutrient Information Center. Fiber. Available here. For a quick answer click here.

Explanation

The existing information points to different results concerning the implications of dietary fiber and the incidence of colon cancer.

The following major studies are available:

  • The majority of case-controlled studies conducted before 1990 found a correlation between higher fiber intake and a lower incidence of colorectal cancer; (2)Trock B, Lanza E, Greenwald P. Dietary fiber, vegetables, and colon cancer: critical review and meta-analyses of the epidemiologic evidence. J Natl Cancer Inst. 1990 Apr 18;82(8):650-61. Available here. (3)Howe GR, Benito E, Castelleto R, Cornée J, Estève J, Gallagher RP, et al. Dietary intake of fiber and decreased risk of cancers of the colon and rectum: evidence from the combined analysis of 13 case-control studies. J Natl Cancer Inst. 1992 Dec 16;84(24):1887-96. Available here.
  • Most prospective cohort studies have not found a correlation between dietary fiber and colorectal cancer; (4)Oregon State University. Micronutrient Information Center. Fiber. Available here.
  • A combined analysis of 13 prospective cohort studies involving over 700,000 adults have not found a correlation between high dietary fiber intake and colorectal cancer; (5)Park Y, Hunter DJ, Spiegelman D, Bergkvist L, Berrino F, van den Brandt PA, et al. Dietary fiber intake and risk of colorectal cancer: a pooled analysis of prospective cohort studies. JAMA. 2005 Dec 14;294(22):2849-57. Available here.
  • The largest prospective study involving over half a million men and women has shown that dietary fiber reduces the risk of colon cancer; (6)Bingham SA, Day NE, Luben R, Ferrari P, Slimani N, Norat T, et al. Dietary fibre in food and protection against colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC): an observational study. Lancet. 2003 May 3;361(9368):1496-501. Available here. Four controlled clinical trials did not find evidence of correlation between the diet high in fiber, fruit and vegetables and low in fat with the risk of recurrence of colorectal adenomas. (7)Schatzkin A, Lanza E, Corle D, Lance P, Iber F, Caan B, et al. Lack of effect of a low-fat, high-fiber diet on the recurrence of colorectal adenomas. Polyp Prevention Trial Study Group. N Engl J Med. 2000 Apr 20;342(16):1149-55. Available here.

These studies are believed to have given different results due to following possible reasons (8)Oregon State University. Micronutrient Information Center. Fiber. Available here.:

  • Inadequate type or amount of fiber used in the studies to prevent cancer incidence;
  • Other dietary factors that might have interfered with the fiber action;
  • Other components in the diet that could have been responsible for some results;
  • In the observational studies potentially incorrect methods for assessing fiber intake were used.

Conclusion

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While waiting for more high quality studies to find the correlation between fiber and reduced risk of colon cancer, continue including plenty of fiber-rich foods in your diet. The benefits of dietary fiber are ample and a potential reducing the risk of cancer is not excluded.

References   [ + ]

1. Oregon State University. Micronutrient Information Center. Fiber. Available here.
2. Trock B, Lanza E, Greenwald P. Dietary fiber, vegetables, and colon cancer: critical review and meta-analyses of the epidemiologic evidence. J Natl Cancer Inst. 1990 Apr 18;82(8):650-61. Available here.
3. Howe GR, Benito E, Castelleto R, Cornée J, Estève J, Gallagher RP, et al. Dietary intake of fiber and decreased risk of cancers of the colon and rectum: evidence from the combined analysis of 13 case-control studies. J Natl Cancer Inst. 1992 Dec 16;84(24):1887-96. Available here.
4. Oregon State University. Micronutrient Information Center. Fiber. Available here.
5. Park Y, Hunter DJ, Spiegelman D, Bergkvist L, Berrino F, van den Brandt PA, et al. Dietary fiber intake and risk of colorectal cancer: a pooled analysis of prospective cohort studies. JAMA. 2005 Dec 14;294(22):2849-57. Available here.
6. Bingham SA, Day NE, Luben R, Ferrari P, Slimani N, Norat T, et al. Dietary fibre in food and protection against colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC): an observational study. Lancet. 2003 May 3;361(9368):1496-501. Available here.
7. Schatzkin A, Lanza E, Corle D, Lance P, Iber F, Caan B, et al. Lack of effect of a low-fat, high-fiber diet on the recurrence of colorectal adenomas. Polyp Prevention Trial Study Group. N Engl J Med. 2000 Apr 20;342(16):1149-55. Available here.
8. Oregon State University. Micronutrient Information Center. Fiber. Available here.

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