The study results were reported in the American Journal of Clinical Nutrition.
Gong Yang and colleagues from Vanderbilt University School of Medicine in Nashville, Tennessee, writes that soy and some of its constituents, such as isoflavones, have been shown to have cancer inhibitory effects.
Researchers looked at more than 68 000 women aged between 40 to 70, who were healthy at enrollment. The women were given questionnaires that determined the amount of soy in the diet at the start of the study and six years later.
They found that 321 of the women developed colorectal cancer during just over six years of follow up and that total soy food intake was inversely associated with colorectal cancer risk. The reduction in risk was dose dependent, with the women who ate the most soy products reducing their colorectal cancer risk the most.
The effect was only seen in postmenopausal women.
