Prospective cohort study of soy food intake and colorectal cancer risk in women.

Yang G, Shu XO, Li H, Chow WH, Cai H, Zhang X, Gao YT, Zheng W
Am J Clin Nutr. 2009 89 (2): 577-83

PMID: 19073792 · PMCID: PMC2643871 · DOI:10.3945/ajcn.2008.26742

BACKGROUND - Soy and some of its constituents, such as isoflavones, have been shown to have cancer-inhibitory activities in experimental studies. Data from epidemiologic studies linking usual soy food intake with colorectal cancer are limited and inconsistent.

OBJECTIVE - The objective was to investigate whether soy food intake is associated with colorectal cancer risk.

DESIGN - We prospectively examined 68,412 women aged 40-70 y and free of cancer and diabetes at enrollment. Usual soy food intake was assessed at baseline (1997-2000) and reassessed during the first follow-up (2000-2002) through in-person interviews with a validated food-frequency questionnaire. We excluded the first year of observation to minimize lifestyle changes related to preclinical disease.

RESULTS - During a mean follow-up of 6.4 y, 321 incident colorectal cancer cases were identified. After adjustment for potential confounding factors, total soy food intake was inversely associated with colorectal cancer risk. Each 5-g/d increment in intake of soy foods as assessed by dry weight [equivalent to approximately 1 oz (28.35 g) tofu/d] was associated with an 8% reduction in risk (95% CI: 3%, 14%). Women in the highest tertile of intake had a multivariate relative risk of 0.67 (95% CI: 0.49, 0.90) compared with those in the lowest tertile (P for trend = 0.008). This inverse association was primarily confined to postmenopausal women. Similar results were also found for intakes of soy protein and isoflavones.

CONCLUSION - This prospective study suggests that consumption of soy foods may reduce the risk of colorectal cancer in postmenopausal women.

MeSH Terms (19)

Adult Aged China Cohort Studies Colorectal Neoplasms Feeding Behavior Female Follow-Up Studies Health Surveys Humans Incidence Middle Aged Postmenopause Prospective Studies Risk Assessment Risk Factors Soybeans Soy Foods Surveys and Questionnaires

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