Dietary Fiber and Risk of Colorectal Cancer in the Japan Collaborative Cohort Study
- Kenji Wakai1,
- Chigusa Date5,
- Mitsuru Fukui6,
- Koji Tamakoshi2,
- Yoshiyuki Watanabe7,
- Norihiko Hayakawa8,
- Masayo Kojima4,
- Miyuki Kawado9,
- Koji Suzuki10,
- Shuji Hashimoto9,
- Shinkan Tokudome4,
- Kotaro Ozasa7,
- Sadao Suzuki4,
- Hideaki Toyoshima2,
- Yoshinori Ito3,
- Akiko Tamakoshi3 and
- for the JACC Study Group
- 1Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute; 2Department of Public Health/Health Information Dynamics, and 3Department of Preventive Medicine/Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine; and 4Department of Health Promotion and Preventive Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan; 5Faculty of Human Life and Environment, Nara Women's University, Nara, Japan; 6Department of Public Health, Osaka City University Graduate School of Medicine, Osaka, Japan; 7Department of Epidemiology for Community Health and Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan; 8Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan; and 9Department of Hygiene, Fujita Health University School of Medicine and 10Department of Public Health, Fujita Health University School of Health Sciences, Toyoake, Japan
- Requests for reprints:
Kenji Wakai, Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya 464-8681, Japan. Phone: 81-52-764-2988; Fax: 81-52-763-5233. E-mail: wakai{at}aichi-cc.jp
Abstract
To examine the association of dietary fiber with the risk of colorectal cancer in a population with a high incidence of cancer and a low fiber intake, we analyzed the data from the Japan Collaborative Cohort Study. From 1988 to 1990, 43,115 men and women aged 40 to 79 years completed a questionnaire on dietary and other factors. Intake of dietary fiber was estimated using a food frequency questionnaire. Rate ratios (RR) were computed by fitting proportional hazards models. During the mean follow-up of 7.6 years, 443 colorectal cancer cases were recorded. In all participants, we found a decreasing trend in risk of colorectal cancer with increasing intake of total dietary fiber; the multivariate-adjusted RRs across quartiles were 1.00, 0.96 [95% confidence interval (95% CI), 0.72-1.27], 0.72 (0.53-0.99), and 0.73 (0.51-1.03; Ptrend = 0.028). This trend was exclusively detected for colon cancer: the corresponding RRs were 1.00, 0.90 (95% CI, 0.64-1.26), 0.56 (0.38-0.83), and 0.58 (0.38-0.88; Ptrend = 0.002). The decrease in RRs with increasing intake of dietary fiber was larger in men than in women. No material differences appeared in the strength of associations with the risk between water-soluble and insoluble dietary fiber. For food sources of fiber, bean fiber intake was somewhat inversely correlated with colorectal cancer risk. This prospective study supported potential protective effects of dietary fiber against colorectal cancer, mainly against colon cancer. The role of dietary fiber in the prevention of colorectal cancer seems to remain inconsistent, and further investigations in various populations are warranted. (Cancer Epidemiol Biomarkers Prev 2007;16(4):668–75)
Footnotes
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Grant support: Grant-in-Aid for Scientific Research on Priority Areas (2) (14031222) from the Ministry of Education, Culture, Sports, Science and Technology of Japan, and by a traveling grant from the Princess Takamatsu Cancer Research Fund. The JACC Study has also been supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan (Monbusho) (61010076, 62010074, 63010074, 1010068, 2151065, 3151064, 4151063, 5151069, 6279102, 11181101, 17015022, and 18014011).
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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- Accepted January 30, 2007.
- Received August 7, 2006.
- Revision received December 8, 2006.
