Soy and protease inhibitors PART 1
In some non-medical journals and Internet was claimed that soy contains a large amount of harmful substances such as protease inhibitors, lectins, phytic acid and others.
Protease inhibitors are substances that brakes or reduces the digestive enzymes activity, which attack and unfolds the proteins, thus reducing the possibility of using proteins that are no longer digested.
It is known that many vegetables and legumes contain substances that inhibits the enzymes that attacks proteins. All varieties of beans, and peas too, turnip and beet are rich in protease inhibitors.
Soy contains 5-6 different protease inhibitors, a total of about 2 g per 100 g of dry beans.
Experiences on animals have shown that after the consumption of large amounts of raw soybeans may cause nutrition disorders (eg development disorder), because proteases inhibitors neutralize, prevents the action of pancreatic trypsin, thus disturbing the digestion of proteins and resulting in a deficit of some specific amino acids.
In fact, the role of these proteases is precisely that soy valuable protein to not be altered or opened during storage, precisely for the bean to not lose it nutritional value. God knew how to keep the bean nutrients to be available to human.
The observations show that, unlike animals, human pancreatic enzyme, pancreatic trypsin is inhibited only in a small degree by this protease, that effects observed during animal experiments are only partially transposed to people. And there is a one more very important fact: In general, these Inhibitors are thermosensitive, ie, by heating during thermal preparation, most inhibitory substances lose their action or it decreases greatly.
Bean processing to achieve various soy products, whether it’s textured, pates, milk or other forms that mimics meat, leads to a marked decrease of the inhibiting action.
Moreover, lately, there are increasingly more data, regarding the protective action of proteases inhibitors. Now it is known that proteases inhibitors proved to have anticancer and antioxidant effects. Also, they regulate blood sugar and diminish inflammation.
The eating of raw soybean is not accustomed, and the preparation of soymilk sauce, tofu, miso, nato and sufu involves heating and fermentation processes that make substances with undesired action to be inactive or their effect to not be harmful.
Another substance, which was criticized and maybe still is by those less informed is phytic acid. A while ago, the phytic acid in soy beans and whole-grain was considered harmful, because fixes iron and zinc in the intestine, thus reducing the use of mineral substances. So exists an argument against sources of vegetable proteins.
Studies have shown that, in general, the amount of phytic acid, which is found in the alimentation used in industrial countries, does not affect negatively the metabolism of zinc, iron and other substances. Moreover, recent data shows that phytic acid has favorable actions on health, regulating blood sugar levels and protecting against cancer. Natural phytic acid influences killer cell activity, “natural killer cells”, involved in the body defense.