Research article

Dietary fiber showed no preventive effect against colon and rectal cancers in Japanese with low fat intake: an analysis from the results of nutrition surveys from 23 Japanese prefectures

Shigeyuki Nakaji ¹ , Tadashi Shimoyama¹ , Takashi Umeda¹ , Juichi Sakamoto² , Shuji Katsura¹ , Kazuo Sugawara¹ and David Baxter³

¹  Department of Hygiene, Hirosaki University School of Medicine Zaifu-cho 5, Hirosaki, 036-8562 Japan

²  First Department of Internal Medicine, Hirosaki University School of Medicine, Hirosaki, 036-8562 Japan

³  Research Graduate School, Faculty of Social and Health Sciences and Education, The University of Ulster, Shore Road, Newtownabbey, County Antrim, BT37 OQB, Northern Ireland, UK

author email corresponding author email

BMC Cancer 2001, 1:14doi:10.1186/1471-2407-1-14

Published:	29 October 2001

Abstract

Background

Since Fuchs' report in 1999, the reported protective effect of dietary fiber from colorectal carcinogenesis has led many researchers to question its real benefit. The aim of this study is to evaluate the association between diet, especially dietary fiber and fat and colorectal cancer in Japan.

Methods

A multiple regression analysis (using the stepwise variable selection method) was performed using the standardized mortality ratios (SMRs) of colon and rectal cancer in 23 Japanese prefectures as objective variables and dietary fiber, nutrients and food groups as explanatory variables.

Results

As for colon cancer, the standardized partial correlation coefficients were positively significant for fat (1,13, P = 0.000), seaweeds (0.41, P = 0.026) and beans (0.45, P = 0.017) and were negatively significant for vitamin A (-0.63, P = 0.003), vitamin C (-0.42, P = 0.019) and yellow-green vegetables (-0.37, P = 0.046). For rectal cancer, the standardized partial correlation coefficient in fat (0.60, P = 0.002) was positively significant. Dietary fiber was not found to have a significant relationship with either colon or rectal cancers.

Conclusions

This study failed to show any protective effect of dietary fiber in subjects with a low fat intake (Japanese) in this analysis, which supports Fuchs' findings in subjects with a high fat intake (US Americans).