Introduction

It is well recognised that there is a lower incidence of certain cancers, such as breast and prostate cancer, in populations consuming soy as a regular part of the diet ¹ , ² . The risk of developing breast cancer in Japanese women is four to five times lower than in Western women ¹ , and the incidence of prostate cancer is four to tenfold lower in men from certain Asian countries compared to Western men ³ .

Population studies in Asia have found that the consumption of soy foods is correlated with a decreased incidence of various cancers including breast ⁴ , ⁵ , prostate ⁶ , ⁷ , lung ⁸ , stomach ⁹ , ¹⁰ , endometrium ¹¹ and colorectal cancer ¹² , ¹³ . In one American study, consuming soy drinks on two or more occasions per day was linked with up to a 70% reduction in prostate cancer risk among Seventh-day Adventist males ¹⁴ .