To examine the effect of the consumption of dietary factors on the risk of breast cancer in a case-control study in Taiwan.
Two-hundred-and-fifty cases and 219 age-matched controls between the ages of 25 and 74 were interviewed in person between 1996 and 1999. Usual consumption of dietary habits including 100 foods was assessed using a food frequency questionnaire and a nutrient database developed and validated in Taiwanese populations.
Cases consumed significantly more fat than controls. Cases also consumed statistically significant less supplements such as vitamins and mineral than controls. Food group analyses showed that highest quartile of beef and pork intake significantly increased risk in younger women (OR = 2.5, 95% CI = 1.0-6.0) and all women (OR = 2.5, 95% CI = 1.1-3.3). The age- education- and total calorie-adjusted odds ratio (OR) of breast cancer risk comparing the highest and second highest quartile of fat intake to the lowest quartile was 5.1, 95% confidence interval (CI): 2.1-13 and 3.5, 95% CI: 1.4-8.7 among those younger cases (< or =40). A multiple regression model indicates a protective effect of supplements (OR: 0.40, 95% CI: 0.3-07) and a harmful effect of dietary fat (OR: 2.6, 95% CI: 1.4-5.0) for the highest versus lowest quartile in all women.
Our results indicate a strong protective effect of dietary supplements and a harmful effect of dietary fats on the risk of breast cancer among women in Taiwan. These findings should be confirmed in future follow-up studies. Specific amount of dietary supplements and dietary fats should be quantified for a more accurate evaluation on the risk for breast cancer in this population.