Fermented Soy (Part 2) – Getting on the Good Side of Soy

RoseMarie Pierce, B.Sc. Pharm., “The Holistic Pharmacist”

Not All Soy-based Consumer Products Are Created Equal
The multinational soy industry has concentrated its efforts on finding alternative uses and new markets for soybeans and soy by-products. Hundreds of millions of dollars are going into the research, manufacturing and marketing of soy-based products. We can find soy in everything from burgers to breakfast cereals, on both the health food and mainstream supermarket shelves.

Soy’s role as a potent food for health has been well established, yet have we gone overboard?

Most soy-based functional foods are produced from one or more by-products of the soybean industry. After removal of the soybean oil, the remaining de-fatted soy flakes can be processed into various edible soy protein products or used to produce soybean meal for animal feeds. The most popular of these is soy protein isolates. According to Beatrice Trum Hunter, Food Editor of Consumers’ Research Magazine and well-known author of Natural Foods Cookbook: “These protein isolates are obtained by means of a high-temperature process that denatures the protein extensively. In its damaged form, the protein is rendered low in nutritional value.”

Even though there is considerable controversy over the value of consuming large amounts of soy, especially as soy derivatives (i.e. textured vegetable protein-TVP, soy protein isolate), most experts agree that fermentation of the whole soybean produces a highly nutritious, easy-to-digest source of vegetable protein.

Naturally fermented soy comes in two varieties, the traditional Asian soybean products (miso, soy sauce, natto and tempeh) and whole bean fermented soy powder. Traditional fermentation involves a slow chemical change (3 months or more) triggered by bacteria, molds, and/or yeast. To produce a fermented soy powder the soybean is dried, quickly pressure-cooked in a stainless steel cooker, then cultured with a lactobacillus acidophilus strain of bacteria, freeze-dried and ground into a fine powder.

Whole Soybean Fermented Powder: Phytochemicals for the Better

A well-controlled amount of heat, followed by a period of fermentation deactivates the high concentrations of the troublesome phytochemicals, such as: protease enzyme inhibitors, phytic acid, and lectins (hemagglutinins). These phytochemicals are also referred to, by some, as anti-nutrients. The above-mentioned phytochemicals, along with others, are present to different degrees in the raw soybean, soymilks, most soy protein by-products (soy protein isolate, TVP) as well as tofu or bean curd. (See chart)

The most bioactive phytochemicals found in the soybean are the isoflavones. Isoflavones are an important and fast growing topic of interest in the scientific community with more than 1,000 articles published in scientific and medical journals. The fermentation process converts the plant forms of the soy isoflavones into their “free” aglycone form for better absorption and more effective use within the body. The health benefits and possible contraindications of soy protein and isoflavone phytochemicals will be the topic of the next Vista magazine article, Fermented Soy (Part 3).

Phytochemicals are health-providing plant substances that give flavor, color, texture and odor to plants, and the little soybean (glycine max) contains at least 125 of them. Plants manufacture phytochemicals for their own healthy growth and to protect themselves from a number of dangerous invading microbes such as bacteria, viruses, fungi, and parasites. Some microbe-destroying phytochemicals furnish the plant with the equivalent of an immune system.

Phytochemicals found in Soy Properties of Soy Phytochemicals

Protease enzyme inhibitors or trypsin inhibitors, also known as the Bowman-Birk Inhibitor (BBI)
In high doses, diminishes digestion & causes malabsorption of proteins
At low levels, may play a role in cancer protection including breast, skin, bladder, colon, lung, pancreatic & esophageal cancers

Phytic acid (phytates) or inositol hexaphosphate (IP6)
A potent mineral chelator which has the ability to bind minerals (iron, calcium, zinc, and magnesium) & block mineral absorption in the gut, especially in a mineral poor diet
Can act as an antioxidant and, when given as a supplement, may prevent iron-excess oxidative disease states implicated in heart disease, diabetes, arthritis and cancer

Saponins
Reduces blood cholesterol by preventing cholesterol from being absorbed from the gut
Stimulates the immune system; may prevent cancer by protecting DNA from damage
Antioxidant in nature

Lectins or hemagglutinins
Toxins (removed by heating and fermentation) known to clump red blood cells, decreasing their ability to properly absorb oxygen and distribute it throughout the body

Isoflavones (Genistein, Daidzein, and Equol)
A family of plant chemicals known as phytoestrogens, found most predominately in soy
May provide a measure of protection against cancer (through antioxidant activity) and heart disease and provides relief for menopausal symptoms

Phytosterols or Sterols and Sterolins
Steroid-like compounds which have the ability to regulate immune function, reduce colon tumors, and lower cholesterol

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RoseMarie Pierce, B.Sc.Pharm, earned her degree in Pharmacy from Dalhousie University in 1972. After extensive studies in herbal and nutritional medicine, RoseMarie integrated these disciplinary practices with her pharmacy education to become Canada’s first Holistic Pharmacist.