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Soy Protein Isolate Dangers

Unless fermented, soybeans were considered indigestible by the ancient Chinese. Soy contains enzyme inhibitors that interfere with protein digestion in the human body. Absorption of calcium, magnesium, iron and zinc are blocked by soy's phytic acid. Phytoestrogens in soy isoflavones have hormone-like effects. Add pesticides necessary to grow soy and contamination during production of soy protein isolate, and the dangers begin to mount.

  1. Contamination

    • Soy protein isolates is the key ingredient in soy baby formula, some soy milks and meat substitutes. According to nutritionist Sally Fallon, author of "Nourishing Traditions: The Cookbook that Challenges Politically Correct Nutrition," manufacturing soy protein isolate involves acid washing in aluminum tanks that leeches high levels of aluminum into the final product. Nitrites are formed during spray drying, and numerous artificial flavorings, including MSG, are added to improve taste. These chemicals are associated with the development of Alzheimer's disease, cancer and severe allergic reactions.

    Hormone-like Effects

    • Isoflavones in soy protein isolate are primarily genistein, daidzein and glycitein, which are phytoestrogens. Phytoestrogens are plant substances that have hormone-like effects in the human body. The National Toxicology Program recently concluded that there is minimal risk (only negligible risk is a less serious category) to infants fed an exclusive diet of soy formula. The concerns are based on animal studies that show differences in breast development, age of puberty onset and vaginal opening size from a soy-based diet. The toxicology panel admits that infants are more vulnerable than older children and adults, and that the results of feeding practices may not be known for years.

    Breast Cancer

    • Phytoestrogens have been implicated in more rapid growth of breast cancer cells. However, a recent study published in the Journal of the American Medical Association found that an intake of up to 11 grams of soy foods is safe and may even be beneficial for women who have a history of breast cancer treatment. The study was conducted using Asian women who primarily consume fermented soy foods, not concentrated soy protein isolate. Controversy concerning breast cancer and phytoestrogens is likely to continue.

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