Dietary fat, fatty acid intakes and colorectal cancer risk in Chinese adults: a case control study

January 1, 2013 Human Health and Nutrition Data 0 Comments

Dietary fat, fatty acid intakes and colorectal cancer risk in Chinese adults: a case control study

Year: 2013
Authors: Zhong, X. Fang, Y. Pan, Z. Li, B. Wang, L. Zheng, M. Chen, Y. Zhang, C.
Publication Name: Eur J Cancer Prev
Publication Details: Volume 22; Pages 438 – 447

Abstract:

The associations between dietary fat intakes and the risk of colorectal cancer have been examined in many epidemiological studies, but the results have remained inconsistent. This study aimed to examine the associations of total fat and fatty acid intakes with the risk of colorectal cancer in Guangzhou, China. A case control study was carried out between July 2010 and May 2012 in Guangzhou, China. Four hundred and eighty nine
consecutively recruited colorectal cancer cases were frequency matched to 976 controls by age (5 year interval) and sex. A validated food frequency questionnaire was used to collect dietary information by face to face interviews. Multivariate logistic regression models were used to estimate the odds ratios (ORs) and 95 per cent confidence intervals (CIs). The total fat intake was not related to the risk of colorectal cancer, with an OR (95 per cent  CI) of 0.95 (0.68 to 1.32) comparing the highest with the lowest quartiles. Intakes of saturated fat, monounsaturated fat, and n 6 polyunsaturated fat were also not associated with the risk of colorectal cancer. However, a significant inverse association was found between total n 3 polyunsaturated fat, alpha linolenic acid (ALA), and long chain n 3 polyunsaturated fat consumption and the risk of colorectal cancer.  The adjusted ORs of the highest versus the lowest quartile were 0.45  for total n 3 polyunsaturated fat, 0.54 for ALA, and 0.58 for long chain n 3 polyunsaturated fat. This study suggested that total fat, saturated fat, monounsaturated fat, and n 6 polyunsaturated fat intakes were not related to the risk of colorectal cancer. However, increased consumption of n 3 polyunsaturated fat might reduce the risk. (Authors abstract)
Colorectal cancer is the third most common cancer in men and the second most common cancer in women worldwide. Studies examining the associations between subtypes of fatty acids (saturated fat, monounsaturated fat, and polyunsaturated fat) and the risk of colorectal cancer have yielded inconsistent results. Limited research is available in China and the results are conflicting. The aim of the present case control study was to examine the associations of dietary total fat and specific fatty acids with the risk of colorectal cancer in Guangzhou, China. In the present case control study, no statistically significant association was found between total fat, saturated fat, monounsaturated fat, and n 6 polyunsaturated fat intake and the risk of colorectal cancer.  However, high consumption of n 3 polyunsaturated fats, including ALA and individual long-chain n 3 polyunsaturated fats, was associated with a reduced risk of colorectal cancer after adjusting for various confounders. These inverse associations were observed in both men and women, colon and rectal cancers.
Further studies are warranted to verify the protective effect of ALA observed in this study. The potential mechanisms of the protective effect of long-chain n 3 polyunsaturated fat against colorectal cancer include suppression of ARA derived eicosanoid biosynthesis; influences on transcription factor activity, gene expression, and signal transduction pathways; alteration of estrogen metabolism; increased or decreased
production of free radicals and reactive oxygen species; and mechanisms involving insulin sensitivity and membrane fluidity. It is unclear whether ALA exerted a protective effect on colorectal cancer through the same mechanism as the long chain n 3 polyunsaturated fat.  This study carried out in Guangzhou, China, found that consumption of total and individual n 3 polyunsaturated fats was inversely associated with the risk of colorectal cancer. No significant association was found between total fat, saturated fat, monounsaturated fat, and n 6 polyunsaturated fat intakes and the risk of colorectal cancer. More studies are warranted to verify the protective effects of ALA and long chain n 3 polyunsaturated fat observed. (Editors comments)



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