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.