Source: Concerns Regarding Soybeans at rheumatic.org
It was abstracted from an article written by Sally Fallon and Mary Enig, Ph.D. (an international expert renown in the field of lipid chemistry) for Health Freedom News in September of 1995.

Some concerns are listed below; see above web site for more information.

  • Soybeans are high in phytic acid or phytates. This is an organic acid, which blocks the uptake of essential minerals-calcium, magnesium, iron and especially zinc-in the intestinal tract.
  • Nitrosamines, which are potent carcinogens, are often found in soy protein foods and are greatly increased during the high temperature drying process.
  • The food industry also touts soy products for their cancer preventing properties. Isoflavone aglycones are anticarcinogenic substances found in traditionally fermented soybean products. However, in non-fermented soy products such as tofu and soy milk, these isoflavones are present in an altered form as beta-glycoside conjugates, which have no anti-carcinogenic effect. Some researchers believe the rapid increase in liver and pancreatic cancer in Africa is due to the introduction of soy products there.
  • Human feeding tests to determine the cholesterol lowering properties of soy protein isolate have not shown them to be effective.
  • Traditional fermented soy products such as miso, natto and tempeh, which are usually made with organically grown soybeans, have a long history of use that is generally beneficial when combined with other elements of the Oriental diet including rice, sea foods, fish broth, organ meats and fermented vegetables.
  • Precipitated soybean products are problematical, especially when they form the major source of protein in the diet. Modern soy products including soy milks and artificial meat and dairy products made from soy protein isolate and textured vegetable protein are new to the diet and pose a number of serious problems.
The article above also states:
"The first soy foods were fermented products like tempeh, natto, miso and shogu (soy or tamari sauce). At a later date, possibly in the 2nd century B.C., Chinese scientists discovered that a puree of cooked soybeans could be precipitated to make a smooth pale curd -tofu or bean curd. It is the bland precipitated products that are most frequently used, accounting for approximately 90% of the processed soybeans consumed in Asia today."

On the other hand
In October 1999, the FDA authorized the use of a health claim on food labels to communicate that consuming 25 grams of soy protein per day as part of a diet low in saturated fat and cholesterol may reduce the risk of coronary heart disease.

At www.sutterhealth.org/health/healthinfo/index.cfm they say:
Soy, a staple food in many Asian countries, contains valuable constituents, including protein, isoflavones, saponins, and phytosterols. Soy protein provides essential amino acids. When eaten with rice, soy provides protein comparable to that found in animal products.

The isoflavones in soy, primarily genistein and daidzein, have been well researched by scientists for their antioxidant and phytoestrogenic properties. 1 Saponins enhance immune function and bind to cholesterol to limit its absorption in the intestine. Phytosterols and other components of soy have been reported to lower cholesterol levels.

Isoflavones may reduce the risk of hormone-dependent cancers, such as breast and prostate cancer, as well as other cancers.

Relatively large amounts of isoflavones are present in whole soybeans, roasted soy nuts, tofu, tempeh, soy milk, meat substitutes, soy flour, and some soy protein isolates.

At the UC Berkeley Wellness Letter they say:
"Soy foods are well worth adding to your diet, since they may reduce the risk of heart disease. Other possible health benefits—not so well established—include protection against breast and prostate cancer and osteoporosis. Soy is not magical; it cannot fix up a poor diet. On the other hand, there is no convincing evidence that soy foods are harmful. People have been eating them for millennia, particularly in Asia. Remember that not all soy products are created equal—soy sauce, for instance, contains no soy protein. Even soy foods with a heart-healthy label may be high in salt, sugar, and calories. Be sure to read the labels."

See Also:
Should Women with Breast Cancer Eat Soy?