Soybean is used to support the prostate body system primarily due to its content of isoflavones, particularly genistein and daidzein, which are classified as phytoestrogens. These compounds have attracted scientific interest for their potential role in hormone-related cancers, including prostate cancer. Epidemiological studies have observed lower rates of prostate cancer in populations with high soy consumption, such as those in some Asian countries. Several in vitro and animal studies suggest that soy isoflavones may inhibit the growth of prostate cancer cells and modulate androgen metabolism, potentially reducing prostate cancer risk or progression.

Human clinical evidence is more limited and mixed. Some randomized controlled trials (RCTs) and meta-analyses have reported modest reductions in prostate-specific antigen (PSA) levels and potential risk reduction for prostate cancer with soy or isoflavone supplementation, while others have found no significant effects. The American Institute for Cancer Research notes that while there is some evidence for a protective effect, it is not conclusive enough for formal dietary recommendations specifically for prostate health. Overall, the use of soybean for supporting the prostate is justified by a moderate level of scientific evidence, but more large-scale, high-quality human trials are needed to establish clear benefits.