With the growing popularity of vegan and vegetarian diets, soy is being touted as an important health food. Being rich in high-quality protein and low in fat, it is considered an excellent alternative to meat.
Soy is a nutritional powerhouse, being rich in iron, calcium, zinc, folate, fiber, B vitamins, vitamin K, omega-3 fatty acids and other nutrients. It improves heart health, promotes healthy bones and helps ease menopause symptoms.
However, many soy foods sold today are unfermented and do not have the same benefits as the fermented versions like soy miso, tempeh, fermented tofu, and natto. Soy sauce also should be fermented, but most soy sauces nowadays are chemically made rather than naturally fermented.
Soybeans naturally contain anti-nutrients that act as the immune system of the soybean plant, protecting it from bacteria, fungi, and viruses. They also give a bitter taste to the plant to make it unpleasant for foraging animals.
These natural toxins are detrimental to human health as well. Anti-nutrients are substances that interfere with the body’s ability to absorb nutrients. The fermenting process is the best way to neutralize these substances and necessary for soy to truly provide the health benefits that are so often advertised.
Researchers have linked unfermented soy foods to increased cancer risk, reduced male fertility, damaged brain function, early onset of puberty and developmental abnormalities in infants.
Here are some soy anti-nutrients and their negative effects on health.
Phytate, also called phytic acid, is present in all legumes, but it is particularly high in soybeans. It blocks the uptake of minerals like iron, calcium, magnesium, copper, and zinc in the gastrointestinal tract.
This leads to nutritional deficiencies, especially zinc deficiency, causing growth delays, loss of appetite, dermatitis, hair loss, immune disorders, and other problems. Zinc is also a vital mineral for mental health.
Soaking and fermentation causes the release of an enzyme that considerably reduces phytate content. Soybeans, in particular, need to be fermented to get rid of this anti-nutrient.
Soybeans are rich in enzyme inhibitors that interfere with the digestive process by inhibiting the release of digestive enzymes. This causes digestive distress, such as bloating and flatulence, when the bacteria in the large intestine try to break down food that has not been digested properly.
Soybeans also have high levels of trypsin inhibitors that interfere with protein digestion.Tryspin is an enzyme required to digest protein.The trypsin inhibitors and anti-proteolytic activity also contribute to vitamin B12 deficiency as trypsin helps in the assimilation of this vitamin.
Traditional fermentation helps deactivate enzyme and trypsin inhibitors in raw soybeans.
Goitrogens present in soybeans block the production of thyroid hormones and interfere with proper functioning of the thyroid gland. These substances can also cause goiter, an enlargement of the thyroid. They are of particular concern related to an underactive thyroid (hypothyroidism).
Though it is believed that soy tends to interfere with absorption of thyroid medication, there still is no evidence that supports completely eliminating soy from the diet.
Soybeans contain high levels of haemagglutinins that cause red blood cells to agglutinate or clump together. This promotes clots and impairs the cells’ ability to properly absorb and distribute oxygen to the body’s tissues.
Heat treatment and sprouting tend to lower the levels of these anti-nutrients. However, traditional fermentation is much more effective in this regard.
Isoflavones are a type of phytoestrogen with a mild estrogenic as well as an anti-estrogenic effect. They help alleviate symptoms of menopause in women and protect against breast cancer.
On the flipside, these estrogen-like compounds tend to disrupt the endocrine function. In addition, animal studies indicate early exposure to genistein and daidzein in soybeans may reduce fertility in women and disrupt the structural development of reproductive organs. Studies have also linked these compounds to thyroid disturbances.
Most soy products found in the market today are made with soy protein isolate, which is produced at high temperatures and pressures. The process removes some of the anti-nutrients, but it also causes denaturation of many proteins. The chemical processing also leads to the formation of toxic lysinoalanine and nitrates, which are potent carcinogens.
Plus, soy protein isolates, whole soybeans, soy milk, soy chips, soy flour, and other products prepared from processed soybeans also have high levels of phytate.
Though there is no conclusive evidence to date, there are also concerns about the long-term effects of soy isoflavones on infants fed soy infant formulas that contain soy protein isolate as the main ingredient.
Another important concern is that more than 90 percent of soy produced in the U.S. is genetically modified. Animal studies have shown that consumption of genetically modified soybeans can cause problems like sterility, birth defects, higher offspring death rates, and allergies.
To conclude, soy foods are meant to be consumed after fermentation that neutralizes the toxins. Moreover, soybeans are more beneficial when enjoyed in their whole food form, not processed. Like all foods, experts recommend consuming organic fermented soy products in moderation.