Can Soybean Reduce The Risk Of Prostate Cancer?

For most of us, soy sauce is the faithful condiment which gives that dish of Chinese an extra kick. But soy is much more than just a staple ingredient at your favorite Chinese joint. A good source of protein and soluble fiber, soy has many powerful phytonutrients and is low in saturated fats.1. And now, this versatile ingredient is proving to be a cancer fighter too.

Research has found that isoflavones, which are phytoestrogens found in soy, may protect against cancer. Phytoestrogens are chemically and structurally similar to human estrogen and have estrogenic properties, although in smaller measures. They have now been found to have a protective influence against prostate cancer and other hormone-dependent cancers.2 Isoflavones also have antioxidant, antimicrobial, and antifungal properties.3 In animal studies they have been shown to inhibit the growth of cancer cells by influencing genes that affect the cell cycle, inducing cell death (apoptosis), and interfering with the signaling pathways of these cells. They can also prevent tumors from developing their own blood supply (angiogenesis) and can inhibit the growth of secondary tumors (metastasis).4


Soy Isoflavones And Prostate Cancer

A number of studies have looked at the effect of soy components on prostate cancer cells. One study across 42 countries found that soy products have a significantly protective influence against prostate cancer. In fact, per kilocalorie it had at least four times as large an effect as that of any other dietary factor.5

The impact of soy is attributed to the major isoflavones in the soybean, namely glycitein, daidzein, and genistein (which may be the most bioactive).6 Genistein especially can inhibit the synthesis of prostaglandins, which encourages inflammation and plays a role in cell proliferation, apoptosis, and metastasis.7


In one study, human prostate cancer cells were treated with genistein or daidzein. They were found to down-regulate the interleukin-8 gene, which is connected to cancer progression, and the growth factors associated with angiogenesis.8

Powering On Together

Some studies have compared the effects of individual isoflavones with isoflavone combinations on prostate cancer cells. When human prostate cancer cells were treated with a soy extract (containing glycitein, genistein, and daidzein), daidzein, and genistein individually, the soy extract induced cell cycle arrest and cell death in prostate cancer cells to a greater degree than did treatment with either daidzein or genistein. It was also found that genistein and daidzein induced cell death in noncancerous benign prostatic hyperplasia (BPH) cells. However, the soy extract didn’t affect the noncancerous cells. This suggests that a combination of these bioactive compounds is better than individual compounds – therefore, making a case for whole foods than individual compounds.9


Go The Asian Way: Say Yes To Soy!

Soy products are an important part of the diet in many Asian countries. And it’s worth noting that the rate of prostate cancer is much lower in Asian countries than in the United States and European countries.10

So how much soy should you have? Americans and Europeans consume less than 1 gram of soy protein per day, while Asian diets seem to have a much higher amount. The Japanese have about 8.7 g of soy protein per day; Indonesians, about 7.4 g; Koreans, 6.2–9.6 g; and the Chinese, 3.4 g. About 2–3 servings of soy a day should be beneficial.11


There are many ways to get soy in – try pancakes made with soy flour, ice cream made from soy milk, or just plain stir-fried soybeans. Research has also shown that the consumption of soy foods like soy milk and tofu is associated with a reduction in prostate cancer risk of ~30%.12 So to protect your prostate, try some soy milk with your cereal today!