Soy And Prostate Cancer


Doctors say soy is beneficial in reducing the risk of breast cancer and other cancers, but what has not yet been explored is the theory that soy helps prevent prostate cancer. However, more and more research is showing there may be a connection between soy and the prevention of prostate cancer. Earlier studies conducted in Europe have led to larger studies in the United States.

The interest in soy and prostate cancer has been around for many years. A study in 1998, led by researchers in Norway, looked at the relationship between soy milk and prostate cancer risk. This research found men who consumed high amounts of soy milk successfully reduced their risk of prostate cancer. Furthermore, population studies have found that prostate cancer is much more prevalent in the West than the East. The research shows Japanese and Chinese men tend to eat more soy than men in the United States. Specifically, researchers found the highest intake of soy was correlated with the lowest incidence of prostate cancer.

A study reported in the Prostate journal in May 2004 also examined the relationship between prostate cancer and soy. The study included men who had early stage prostate cancer in the "watch and wait" group. This means rather than receiving chemotherapy or radiation, the men were being followed closely for a rise in their PSA levels. This is often a popular choice among men whose cancer may be spreading slowly. The participants either consumed soy shakes for three months or drank shakes without soy. Researchers then looked at their PSA to determine the progression of the disease. PSA is a marker used to determine disease progression. The study found 69 percent of the men who drank the soy shakes either had a reduction in their PSA or it remained stable after three months. Furthermore, 20 percent of the men on soy had more than a 3-point drop in their PSA. Excited about these findings, researchers are conducting a larger trial where men are given soy supplements or a placebo for three months. That study is still ongoing.

So how much soy will make a difference? Experts recommend two to three ounces, two to three times a week to reduce cancer risk. While soy supplements may help, the optimal recommendation is to get soy from foods. Especially tofu and miso because they are absorbed better by the body.


Nagi B. Kumar, Ph.D., R.D.

Moffitt Cancer Center

12902 Magnolia Dr, MBC-PR

Tampa, FL 33612-9497