The Recommended Dietary Allowance of protein for adult males (aged 25-50) is approximately 63 grams and 50 grams for adult females (aged 25-50). Soy products can provide a significant portion of one's daily protein needs.
Helps to Prevent Cancer of the Breast, Prostate, Colon and Uterus (Endometrium)
Several recent scientific studies have shown that a regular intake of traditional soy foods may help to prevent breast cancer, prostate cancer and colon cancer. One recent study related to soy products and prostate cancer prevention determined that:
"...soy products were found to be significantly protective ... with an effect size per kilocalorie at least four times as large as that of any other dietary factor."
Researchers believe that the cancer protective effects from soy are due to the group of plant chemicals known as isoflavones, particularly genistein and daidzein. It is theorized that these isoflavones prevent cancer by inhibiting the growth of existing tumor cells (as opposed to preventing the development of tumor cells).
One epidemiological study showed that individuals who had high amounts of soy isoflavones measured in their urine (signifying that they had a regular intake of soy foods) had approximately one-half the breast cancer risk of those who had low amount of measured soy isoflavones in their urine.
Colon cancer rates (like breast and prostate cancers) are very low in countries with higher intakes of traditional soy products. Controlled scientific research related to soy products and colon cancer is still in the preliminary stages. One study in Hawaii found that vegetable fiber and certain vegetables and legumes (including soy products) help to lower the risk of colon cancer.
One study in Hawaii found soy product intake associated with lower risk of endometrial cancer. However, the effects of soy and legumes were limited to women who had never been pregnant and never used estrogens. Other aspects of the diet lowered the risk as well, including vegetables grains, sea vegetables, and fruits.
Helps to Prevent Heart Disease
It is known that in countries were traditional soy products are ingested regularly, the rates of cardiovascular diseases is low. There is some research that suggests that soy foods may help to prevent heart disease by reducing total cholesterol, low density lipoprotein cholesterol, blood pressure and possibly preventing plaque buildup in the arteries (atherosclerosis). It is believed that the isoflavones from soy foods are the primary factors involved in these beneficial health effects.
May Help to Prevent Osteoporosis
Another factor in the possible effectiveness of soy to prevent osteoporosis may be its content of the group of plant chemicals known as Isoflavones. Several studies have suggested that the isoflavones in soy products may be a factor in helping to prevent bone loss. In fact, one study in animals showed that soy intake may be as extremely effective in suppression of bone loss. However, preliminary results from human studies appear to indicate that the benefit may not be as great in humans.
May Help to Prevent or Alleviate Menopausal Symptoms
There is some scientific evidence that soy products may help to prevent or alleviate menopausal symptoms. However, the research is still in a preliminary stage.