title: A case-control study on risk of changing food consumption for colorectal cancer.
abstract: OBJECTIVE
  To investigate the relative risk factor of food items for colorectal cancer in four time periods through a case-control study in a Chinese rural area.
  
  
  METHODS
  Colorectal cancer patients diagnosed at a county cancer center, Hebei Province, China, and non-cancer outpatients with similar age, sex, and place of residence were selected for cases and controls, respectively. There were 102 (93.6%) colorectal cancer patients and 99 (90.8%) outpatients being the cases and controls, respectively in the present investigation, who agreed to be interviewed about their food intake, during a 20-year period, through a food frequency questionnaire. The risks of intake of different food items and lifestyle for colorectal cancer were compared between cases and controls.
  
  
  RESULTS
  During the 20-year period, diets of both cases and controls changed with increase in intake of animal foods and fruits, and alcohol consumption tended to increase. In the food items, milk intake showed a protective effect in both males and females, and the odds ratios were 0.38 (95% CI 0.16-0.90) and 0.28 (95% CI 0.10-0.81) for males and females, respectively. A reduced risk of fruit intake could be seen in males, while a reduced risk of vegetables could be observed in females. Meat intake and saturated fats were the prominent risk factors for colorectal cancer in males and females, respectively. A comparison of life habits, showed that tea drinking had a consistent protective effect in females, and the odds ratios were 0.21 (0.08-0.58), 0.23 (0.08-0.67), 0.25 (0.10-0.64), and 0.11 (0.04-0.30) for periods of 20-, 10-, 5-years ago, and current time, respectively.
  
  
  CONCLUSIONS
  These findings indicate that change in food consumption is strongly associated with a change in risk of colorectal cancer, and dietary meat has increased the risk of colorectal cancer. Increase in the consumption of milk and fruits may be a significant measure for colorectal cancer prevention in low-incidence areas.
authors.affiliation: Department of Public Health, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, Nagano Prefecture 390-8621, Japan. zbing@sch.md.shinshu-u.ac.jp
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Xiangping
authors.initials: X
authors.lastname: Li
authors.forename: Hidenori
authors.initials: H
authors.lastname: Nakama
authors.forename: Xing
authors.initials: X
authors.lastname: Zhang
authors.forename: Ning
authors.initials: N
authors.lastname: Wei
authors.forename: Xiulan
authors.initials: X
authors.lastname: Zhang
authors.forename: Leshan
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D004032:Diet / Q000009:adverse effects*; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D012424:Rural Population; D011795:Surveys and Questionnaires