Source: Am J Clin Nutr, February 2009;89(2):577-83.
Research: Soy and some of its constituents, such as isoflavones, have been shown to have cancer-inhibitory activities in experimental studies. However, data from epidemiologic studies linking usual soy food intake with colorectal cancer are limited and inconsistent. The objective of this study was to investigate whether soy food intake is associated with colorectal cancer risk. Researchers prospectively examined 68,412 women aged 40-70 years 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. Investigators excluded the first year of observation to minimize lifestyle changes related to preclinical disease.
Results: During a mean follow-up of a little more than 6 years, 321 incident colorectal cancer cases were identified. After adjustment for potential confounding factors, total soy food intake was inversely associated with colorectal cancer risk. This inverse association was primarily confined to postmenopausal women. Similar results were also found for intakes of soy protein and isoflavones.