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Dangers of Soy

dangers of soySoy foods have become VERY popular these days. However, there seems to be a lot of controversy over the health benefits of soy. I am going to explain both sides of the story without bias, then I will give you my opinion, as I normally advice my clients.


It all starts with the soybean (aka edamame). Soybeans are the purest form of soy. When the bean is processed, numerous soy products can be made.

Glossary of Soy

Tofu: soybean curd
Tempeh: fermented soy curd
Soymilk: grinded soybeans w/ water and rice syrup
Soy Flour: ground up soybeans
Miso: fermented soybean paste
Soy Sauce: fermented soybeans, wheat, and sugar
Soybean Oil: oil extracted
Soy Protein Isolate: high protein slush left after oil extraction

In the US, 79% of fats used is soybean oil! There is a huge demand for soy oil due to the increase in convenience foods. When the oil is extracted, soy protein isolate (SPI) is left. This byproduct is added to almost all processed soy foods for added protein. This is the source for a $1.6 billion market of imitation foods.

What’s GMO Soy? GMO is genetic modification using modern biotechnology. Approximately half of the soybean crop planted in 1999 carries a gene that makes it resistant to herbicides. There are definite health concerns related to GMO soy, including allergies and gene transfer (antibiotic resistant genes).


In 1999, the FDA authorized the use of a health claim for soy protein: 25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.

This claim refers to intact soy protein, not the SPI. There has been many studies that suggest that the consumption of soy also improves bone health, relieves menopause symptoms, and helps prevent certain cancers.


Many health experts strongly disagree with all these health claims. There are numerous studies that display opposite results. They say that soy companies, specifically Solae, are manipulating the current data for their financial success. Concerns have arose about certain components of soy protein, especially isoflavones. Isoflavones are a weak form of estrogen that can disrupt the endocrine system. They may be linked to estrogen and thyroid imbalances. Also, high levels of phytic acid in soy may reduce the absorption of minerals, including Calcium and Magnesium.


My advice to clients for almost all nutrition issues is to:

  • eat food in its most natural form
  • avoid foods that are highly processed
  • eat a wide variety of foods

Well, the same goes for soy. Other than the whole soybeans, most byproducts are highly processed. Read ingredient labels— try to avoid preservatives and additives (MSG, lots of sodium, and sweeteners).

Soybean oil becomes a damaged fat when heated at high temperatures. It’s best to avoid soy oil in cooked foods, GMO soy and any highly processed soy products.

Fermented soy may be better tolerated than whole soy. The fermentation process breaks down the beans’ complex proteins for easier digestion.

I never recommend high doses of soy protein on a daily basis. If you enjoy soy, try eating it every third day to avoid complications.

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