Soybean, a leguminous plant product has been considered as one of the most wonderful nutritional gifts that nature has given us, during the last few years. In the nineties, its consumption was strongly recommended to maintain good health and to help prevent and even treat certain diseases. This was because of two main reasons. One, its being nutritionally very rich and the second it's having certain non- nutritional components which have a disease fighting potential.
Apart from having an appreciable amount of various vitamins and minerals, soy contains enough of the three macro nutrients that are required for good health. Despite it being a plant food, soy is a rich source of proteins that have a biological value, almost comparable to animal proteins and an amino-acid pattern, virtually equivalent to proteins of milk and egg. Thus it has an immense potential for narrowing down the protein gap that is found in vegetarian diets, which are consumed by most people in the eastern countries.
In addition to having good quality proteins, soy has enough of fats which can well boast of having an excellent fatty acid profile. Oil from soy contains only minimal saturated fats and almost zero cholesterol, whereas 85% of it is constituted of polyunsaturated fatty acids that are of 'the essential category' i.e. those which, have to be consumed by the human body in the form of food. Most of these fatty acids belong to the linolenic group - the omega-3. Omega-3's are anti coagulants and as such, prevent blood clot formation in the arteries that may lead to brain strokes which can even be fatal. They also lower the levels of total cholesterol, LDL and triglycerides in the blood and improve the ratio of HDL and LDL, besides inhibiting the oxidation of these lipids, which is actually the first step in accumulation of artery clogging plaque. Thus including soy oil in our diet is heart healthy and protects us from cardio vascular diseases.
Talking about the third macro-nutrient i.e. the carbohydrate, soybean is a rich source of that too. Most of its carbohydrate is in the form of cellulose which is an edible fibre and doesn't get digested or absorbed. So soy's carbohydrate calories are not too many and its glycemic-index is also low as its fibre helps in slowing down the absorption of sugars from the digestive tract. This keeps in check the glucose level of blood and reduces the insulin requirement of the body. Soy is therefore, a valuable food to include in a diabetic diet. In normal course too, one needs about 20-30 gram of dietary fibre each day. Whereas, most foods that we usually consume are highly refined and contain little fibre, whole soybeans are quite rich in it and its products also contribute at least some to our diet. More so, clinical studies have shown that soy's fibre has properties, both of soluble as well as insoluble fibre. As soluble fibre it can ferment, so plays an important role in the prevention of colon cancer and in the insoluble form it adds to the intestinal waste, thereby increasing the stool bulk and decreasing its transit time. This also gives soy the advantage of being a food that helps in maintaining weight and lowers blood pressure and the cholesterol level.
Apart from being a rich source of nutrients, soy has some important phytochemicals, which are non nutritional and from which actually stems its disease fighting potential. The phytochemicals in soy are Isoflavones. They are usually referred to as phytoestrogens because their chemical structure resembles the estrogen of the females. But there is an important difference i.e. they are much weaker as compared to the natural hormone. Their low potency gives them a wonderful capability of exerting both estrogenic as well as anti estrogenic effects depending upon the requirement of the body. If the level of more potent estrogens of the body is high, isoflavones of soy block their action and prevent hormone driven diseases such as cancers. In the reverse situation, however, as during menopause, these phytoestrogens substitute the body's hormonal levels and ease symptoms like hot flushes and aid in the prevention of diseases like osteoporosis.
In addition to all this, our wonder food has antioxidant properties, which enhance its anti carcinogenic effects. Several studies have proved that regular consumption of soy-containing diet inhibits the development of breast cancer in females and the prostate cancer in males. It has also been established that calcium excretion through urine is much lower in women who consume soy proteins frequently, as compared to the ones who depend only on animal sources for them. Thereby their bone mineral density is increased, primarily in the spine.
No wonder, campaign for soy consumption has been so enthusiastic. But some new research is now establishing contradicting results. Concerns are, therefore, being raised about its safety. Once hailed as a miracle food, it is slowly becoming centre of a furious debate. Some scientists believe that claims of it being a wonder food are based on scanty facts and half truths. They say that it is known to contain an array of chemicals like phytic acid, trypsin inhibitors and nitrosamines that are highly toxic and can even be carcinogenic. These could increase the risk of brain damage both in men and women and similar abnormalities in children. They give hard evidence linking its high consumption to thyroid dysfunction, cognitive decline, digestive discomforts and even the failure of body's immune system. Not only that, as per their opinion, too much of its use during pregnancy and lactation is believed to have subtle effect on the development of the child apart from it being a risk factor for breast tumour in the mother. Infant formula feeds that are soy based are particularly harmful as they contain a high percentage of phytoestrogens which adversely affect the infant's reproductive health. Babies fed on these formulas, have dangerously high levels of estrogenic compounds in their blood, almost an equivalent of five birth control pills per day and this plays havoc with their sexual growth. This group of nutritionists also claims that soy rich diets if consumed too frequently by men, lead to significant changes in their testosterone levels that may harm their fertility as it lowers the sperm count. Further, some studies have shown that supplements containing concentrated soy phytoestrogens do not in any way improve mood, memory or any other symptoms of menopause; therefore the role of soy isflavones in relieving menopausal discomforts is also doubted. Thus soybean, which has been promoted all these years as a wonder food, which nourishes the body and also prevents & cures all sort of diseases, is perhaps not all that wonderful!
The reason is the toxic chemicals present in it which need to be rendered ineffective by thorough processing. The trouble with modern soy products is that fast industrial processing does not equate to historical methods of preparing, either by fermenting or boiling for a very long time, to detoxify it. Therefore, the harmful chemicals are left in the products only. A study of the history of soy use in Asia, where it originated, shows that it was never adopted by its people as their staple food except by the poor during times of extreme food shortage. This clearly indicates that its use was limited and whenever it was used it was done after carefully preparing it so as to kill its toxins. Because there is, as yet, a lack of evidence to confirm the safety of widespread use of soy while, there is definitely some evidence to suggest that it might be hazardous, thorough research is required to evaluate its health implications.
HOD Home Science,
I.B. College, Panipat.