The Dangers of Soy

August 6, 2012

Many patients ask me why I tell them to stay away from Soy. Here is the low down on Soy. Soy is part of a plant called a legume – same category as peas, lentils, beans and peanuts. Most of the soy in the US is genetically modified or processed. Soy can cause thyroid issues, hormonal imbalances such as excess estrogen and vitamin and mineral deficiencies. Soy can be processed as a fermented or non-fermented product.

Fermented soy is produced by using bacteria to break down the soy. Examples of fermented soy are miso, natto, tempeh, and fermented soy sauce. Fermented soy can be eaten in small amounts without causing nutrient deficiencies or thyroid problems.

Non-fermented soy products contain anti-thyroid agents and enzymes that block the absorption of many vitamins and minerals. The soy in the United States is usually highly processed or genetically modified, which is what diminishes the benefits and increases the risk with Soy. Soy in its natural form contains protease inhibitors. Protease enzymes are what the body uses to break down proteins into amino acids, which we use to maintain and build muscle and bone strength. Soy is a very potent trypsin inhibitor, which results in illnesses of the pancreas as well as cancer. Non-fermented soy products include soy milk, soy-based meat substitutes, soybean oil, tofu, and many spreads with soy in them. Non-fermented soy has been linked to hypothyroidism as well as the autoimmune thyroid conditions such as Hashimoto’s and Graves disease. Soy also acts as a phytoestrogen and has been associated with enlarged breasts in males and could stimulate estrogen receptors in males or females.


References:

  • Allred CD. Soy processing influences growth of estrogen-dependent breast cancer tumors. Carcinogenesis – 01 Sept 2004; 25(9): 1649-57.
  • Barnes S. The biochemistry, chemistry and physiology of the isoflavones in soybeans and their food products. Lymphat Res Biol – 01-March-2010; 8(1): 89-98
  • Narula, Harmeet MD, Carlson, Harold MD. Gynocomastia. Endocrinology and Metabolism Clinics. Volume 36 Issue 2 (June 2007).
  • Rakel: Integrative Medicine 3rd Ed. Warshowsky, Allen MD. Estrogen dominance. Chapter 55.

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