International Journal of Nutrition, Pharmacology, Neurological Diseases

: 2013  |  Volume : 3  |  Issue : 1  |  Page : 64--69

Phytochemicals and nutritional health benefits of soy plant

Mohammad Asif, Mrityunjoy Acharya 
 Department of Pharmacy, Guru Ram Das (PG) Institute of Management and Technology, Dehradun, Uttarakhand, India

Correspondence Address:
Mohammad Asif
Department of Pharmacy, GRD (PG) Institute of Management and Technology, 214, Rajpur Road, Dehradun - 248 901


Health properties and uses of soybean, as well as the different chemical and botanical characteristics of this legume, are shown in this review. Soybean represents an excellent source of high quality protein; it has a low content in saturated fat, it contains a great amount of dietary fiber and its isoflavone content makes it singular among other legumes. Characterization and positive health effects of soybeans have been recently studied. Most of the studies have been focused on soybean protein as a possible source of prevention against cardiovascular disease. This positive effect may be due to a decrease in serum cholesterol concentrations. In addition, there are many studies on isoflavones, non-nutritive substances, associated with prevention and treatment of different chronic diseases. Moreover, some studies have shown the health properties of soy dietary fiber. The efficacy and safety of soy isoflavones for preventing or treating cancer of the breast, endometrium, and prostate are not established. In contrast, many soy products should be beneficial to cardiovascular and overall health because of their high content of polyunsaturated fats, fibers, vitamins, and minerals and low content of saturated fat. Therefore, it would be interesting to consider the replacement of animal based foods for soybean foods in order to obtain some nutritional benefits.

How to cite this article:
Asif M, Acharya M. Phytochemicals and nutritional health benefits of soy plant.Int J Nutr Pharmacol Neurol Dis 2013;3:64-69

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Asif M, Acharya M. Phytochemicals and nutritional health benefits of soy plant. Int J Nutr Pharmacol Neurol Dis [serial online] 2013 [cited 2021 Jan 25 ];3:64-69
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Soy protein has increased attention in recent years among consumers, and researchers. Botanically, soybean belongs to the order Rosaceae, family Leguminosae, the genus Glycine and the cultivar Glycine max. A recent study found that individuals with a habitually health-conscious lifestyle were more likely to consume soy foods than the average person. [1] The purpose of this article is to review the uses and benefits of soy protein foods in normal as well as during pregnancy, postpartum, or infancy. Soybean is a legume that contains no cholesterol and is low in saturated fat. [2] Soybeans are the only vegetable food that contains all eight essential amino acids. [3] Soybeans are also a good source of fiber, iron, calcium, zinc, and B vitamins [Table 1], [Table 2] and [Table 3]. [2] This column reviews the health benefits of soy products with a special focus on human's health including menopausal symptoms, and cancer. [4]{Table 1}{Table 2}{Table 3}

Benefits of soy protein

Soy protein is a high-quality plant-based protein that is equal in protein quality to meat, milk, and eggs. In fact, soy protein is a measure of the digestibility and availability of essential amino acids. Soy protein is very beneficial in various disorders and diseases. [5]

Heart disease

Cardiovascular disease is one of the major health problems in most developed countries. Most deaths due to cardiovascular disease (CVD) are preventable through a lifestyle based on diet, exercise, and no smoking. [6] Soy protein consumption may help lower total blood cholesterol and LDL-cholesterol compared to animal protein consumption. [7] LDL ("bad") cholesterol plays a key role in increasing the risk of coronary heart disease. In addition, soy protein may have an impact in raising HDL ("good") cholesterol. In addition, the consumption of soy protein or isoflavones is a heart-healthy diet for those with elevated total and LDL cholesterol. Oxidized LDL-cholesterol causes damage to arteries. However, preliminary research suggests that the isoflavone genistein, a main component of soy protein, inhibits the oxidation of LDL-cholesterol leading to improved health. [5] The phytoestrogens (plant compounds that have hormone-like effects; isoflavones are the phytoestrogens found in soy) bind to estrogen receptors and produce similar effects including lowering LDL-cholesterol and increasing high-density lipoproteins. [3] Individuals with elevated cholesterol seem to receive the greatest benefit by consuming soy protein. [8] Individuals need to consume about 25 g of soy protein or more each day to obtain results. [9] The Food and Drug Administration approved the health claim for the relationship between soy product consumption and reduced risk of coronary heart disease. [8] A recent study reveals that soy isoflavones significantly reduced serum total and LDL cholesterol but did not change HDL cholesterol and triacylglycerol. Soy protein that contained enriched or depleted isoflavones also significantly improved lipid profiles. [10]

Blood coagulation

Blood clots are often responsible for completely blocking an artery already narrowed by atherosclerosis. Studies suggest that soy isoflavones, especially genistein, have an opposing effect on blood clot formation. Genistein a nonclassical estrogen receptor modulator could affect platelet aggregation through their direct effect on vascular tissue by regulating the synthesis of vasoactive compounds. This reduction of platelet aggregation is mediated through nitric oxide release from vascular tissue. [11]

Blood pressure

Uncontrolled high blood pressure can lead to stroke, heart attack, heart failure or kidney failure. Consumption of soy protein may be linked to lower blood pressure. Researchers continue to examine soy protein's effect on blood pressure. In contrast, many soy products should be beneficial to cardiovascular and overall health because of their high content of polyunsaturated fats, fiber, vitamins, and minerals and low content of saturated fat. The effects of soy protein and isoflavones on several other CVD risk factors-HDL cholesterol, triglycerides, lipoprotein (a), and blood pressure-are as follows. Soy protein, like any other dietary protein, contains calories and could be used in the diet to replace animal or vegetable proteins. Soy protein also could replace other sources of calories such as carbohydrate or fat, raising the total amount of protein eaten and reducing carbohydrate or fat intake. Much less is known about the potential impact on risk factors for CVD of increasing total protein intake by adding soy or other plant protein in place of carbohydrate or fat; this important dietary change is currently being studied. A recent result from this randomized, controlled trial indicates that both soy and milk protein intake reduce systolic blood pressure compared with a high-glycemic-index refined carbohydrate among patients with prehypertension and stage-I hypertension. Furthermore, these findings suggest that partially replacing carbohydrate with soy or milk protein might be an important component of nutrition intervention strategies for the prevention and treatment of hypertension. [12]


The several bioactive compounds contained in soybeans, such as isoflavones, may help reduce the risk of certain cancers. Genistein, one of the phytochemicals found in soy, can reduce the risk of cancers such as breast cancer, prostate cancer. [9],[13] It has been proposed that genistein can prevent tumors and some other kind of cancer by multiple mechanisms. Genistein blocks cancer development by preventing tumors from creating blood vessels that would provide nourishment for growth. [7],[9] Soybean foods may be a factor contributing to the diminution of prostate cancer mortality. [14] Genistein has been shown to reduce DNA synthesis in human prostate cells in vitro and inhibit testosterone effect in prostate cancer development in rats. [15],[16] Another study revealed that soy isoflavone genistein can contribute its anticancer activity for its antioxidant properties. The anticancer effects are more likely due to the fact that genistein is a specific inhibitor of protein tyrosine kinase, MAP kinase, ribosomal S6 kinase, topoisomerase II, which form part of growth factor-stimulated signal transduction cascades in normal and transformed cancer cells. It has also been proved, in vitro, that genistein increases concentrations of TGF-β, which may inhibit the growth of cancer cells. Moreover, genistein has an important role as a potent inhibitor of angiogenesis in vitro . [17] However, a daily intake of soybean enough to decrease LDL-cholesterol, does not reduce serum prostate specific antigen (PSA) as it has been proposed by others studies. [14] There is some epidemiological evidence for protective effects of soybean products on colon cancer but also a number of studies have shown no effect. In vitro studies, soybean products have shown an antiproliferative effect on a wide range of cell types including cells of the gastrointestinal tract. [18] An important role in colon cancer is attributed to dietary fiber, and it also reduces the risk of other chronic diseases in the digestive system. [19],[20] Dietary fiber can increase the volume of fecal material and reduce the colonic transit time; therefore it prevents a low fecal material and infrequent bowel movements that can produce a prolonged exposition of colonic cells to fecal mutagens. Moreover, fiber may dilute bile acids and provide a dispersed solid phase in which bile salts can be absorbed reducing their concentration in fecal water, because it has been presumed that bile acid salts may cause chronic irritation in the colon and stimulate colonic mucosal proliferation and therefore act as tumor promoters. [20],[21] The fermentation of fiber in colon produces an increase of short-chain fatty acids that present a potential protective effect against colon cancer and bowel infections through inhibition of putrefactive and pathogenic bacteria, respectively. [22],[23] Among the short-chain fatty acids, butyrate may act as a regulator of the gene expression that is implicated in colon cells proliferation and differentiation, so it has been proposed that butyrate can be a protection against colon cancer. [18] Dietary flavonoids have shown antiproliferative role for human colon cancer cells. The antiproliferative property of flavonoids could be linked to their ability to inhibit cellular accumulation of ascorbic acid, which is used during cell division. However, there are results showing that isoflavones do not protect against the development of colon cancer in rats treated with a carcinogen and fed with a high fat diet. [18] Published data about soybean isoflavones and colon cancer are conflicting and scientific evidence in support of the protective effect on colon cancer is limited. [14]

Breast cancer

The growth of both estrogen-dependent and estrogen independent breast cancer cells in vitro has been inhibited by genistein, but it is not clear if the concentrations reached in vitro could be reached in vivo. The only statement which can be done is that soybean intake may help to prevent the initiation of cancer cells. [19] However, although the hypothesis estrogenic-antiestrogenic effects of isoflavones exits, there is evidence of isoflavones increasing estrogenic activity in risk breast cancer women and in women suffering already breast cancer. [18],[24]

Women's health

Diet rich in soy protein has a number of health benefits that are unique to women's needs. A diet rich in soy protein may alleviate certain symptoms associated with menopause, help reduce the risk of breast cancer, promote heart health, and maintain bone health. Soybeans are the only vegetable food that contains all eight essential amino acids. [2],[25] Soybeans are also a good source of fiber, iron, calcium, zinc, and B vitamins. [3]


Use of soy products during pregnancy can be encouraged because expectant women are likely to receive the same health benefits as other women. Fortified milk and fortified soymilk are the only reliable dietary sources of vitamin D.[26] All other dairy products contain little or no vitamin D. While many women will obtain enough vitamin D from exposure to sunlight, soymilk may be an alternative for those who are overly sensitive to the sun or for those who simply are not able to be or do not enjoy being outdoors.

Menopausal symptoms

Phytoestrogens are acting like synthetic estrogen to protect women from bone loss and maintain a healthy heart. [9] Soy protein has been found to positively influence bone and calcium balance in postmenopausal women, especially significant for women not receiving hormone replacement therapy. [27] These results were not seen in young, healthy women who were still menstruating. [28]

Obesity and diabetes

Soy protein control hyperglycemia and reduced body weight, hyperlipidemia, and hyperinsulinemia. [27] These characteristics may be useful to both nondiabetic and diabetic persons in the control of obesity and blood sugar. Soybean therapy in diabetic individuals depends on the type of diabetes and other factors such as lifestyle and metabolic needs of the patients. Soybean protein has a role in diabetes because of its content in glycine and arginine, which tend to reduce blood insulin levels. A soybean fiber may be useful because of its insulin-moderated effect. Soybean diet may be a good option in type 2 diabetes individuals due to its effect on hypertension, hypercholesterolemia, atherosclerosis, and obesity, which are very common diseases in diabetic patients. [29] In addition, substituting animal protein for soybean or other vegetable protein may also decrease renal hyperfiltration, proteinuria, and renal acid load and therefore reduces the risk of renal disease in type 2 diabetes. [30] It is generally accepted that a high fiber diet, particularly soluble fiber, is useful to control plasma glucose concentration in diabetics. In short- and long-term experiments improvement in blood glucose attributed to fiber intake from soybeans has been reported. [21],[31] The mechanisms to improve glycemic control during dietary fiber intake seem to be due to the effects of slowing carbohydrate absorption, so that dietary fiber reduces or delays the absorption of carbohydrates. [20] It also increases fecal excretion of bile acid and therefore may cause a low absorption of fat. [30],[31] One of the most common complications of diabetes mellitus is the development of diabetic retinopathy. The antiangiogenic effects of isoflavones could be of value in this disorder, although the role of soybean protein isolates containing isoflavones has not been studied in detail. [32] In addition, soybean is associated with health benefits for patients with gallstones. The mechanism of beneficial effect of soybean on gallstones is not well known but it may be related to the blood cholesterol lowering effects of soybean protein containing isoflavones. [29] Researches performed in diabetic patients with soybean diets show several potential advantages, but at the moment very much work is required to define the exact role of soybean in the control of diabetes mellitus. [33]

Nutritional effects

Soy protein can be used as a source of high-quality protein to help satisfy the higher need for protein during muscle-building by providing the necessary essential amino acids for physical and muscular development. While exercise is healthy, it does create oxidant stress that can contribute to muscle soreness, inflammation, and the development of free radicals. It may speed up muscle recovery after exercise. The isoflavones found in soy protein produce antioxidant effects, which may help reduce soreness and inflammation and may help athletes return to the gym more quickly. [34]

Benefits of soy for special populations

Vegetarians and vegans

Vegetarians (individuals who do not eat meat) and vegans (individuals who do not eat any products from animals, including eggs, milk, and cheese). Vitamin B12 is only found in animal products and, therefore, may be lacking in the diet of vegans. Use of soymilk is one way to obtain this essential vitamin. [2]

Infants with special conditions

Infants born with lactase deficiency or galactosemia are benefit from the use of soy-based formulas. [2] A vegetarian diet may choose to use a soy-based formula for newborns. In addition, infants who are recovering from episodes of diarrhea (given breast-milk substitutes) may have soy formula recommended to facilitate their recovery. While soy-based formulas meet an infant's growth and development needs, they do not offer any advantage over milk-based formulas. [13] Infants who are not able to tolerate lactose formulas (those based on cow's milk, casein/whey-based formulas; e.g., Similac, Enfamil, Carnation) may be prescribed soy-based formulas if they are not breastfed. [9] Each year, about 20-25% of infants are converted to soy protein formulas (American Dietetic Association and Dieticians of Canada [ADA], 2000). The development of lactose-free cow's milk protein-based formulas has made it unnecessary to switch infants to soy-based formula (ADA, 2000), though the practice is still common. The use of soy-based formula is effective in only about 20-50% of infants because the soy protein eventually triggers a reaction in susceptible infants. [9]


Some nutritional advantages could be obtained by replacing many animal based foods for soybean foods. Soybean provides an important source of high-quality protein with a low content in saturated fat and a great amount of dietary fiber. The consumption of soybean protein and dietary fiber seems to reduce the risk of cardiovascular diseases and to improve glycemic control. Soy protein products offer benefits to women in various life stages. Benefits include improved diet and cardiovascular status, prevention of certain types of cancer, improved health following menopause, obesity prevention/control, and more options for food variety. Furthermore, soybean isoflavones are associated with a potential role in the prevention and treatment of different diseases. Therefore, soybean could play an important role for the promotion of health. The area of soy protein research has increased in popularity in recent years among multiple health disciplines. Future research efforts are likely to include more scientific advances in the use of soy in the diet. In October 26th, 1999, the Food and Drug Administration (FDA) in USA approved a health claim based on the role of soybean protein in reducing the risk of coronary heart disease. [35] This claim establishes that the soybean protein included in a diet low in saturated fat and cholesterol may reduce the risk of coronary heart disease. The available researches showed that a frequent soybean protein consumption lowers the cholesterol levels. [36],[37] The results from recent researches suggest that soybean dietary fiber plays a role in the reduction of cholesterol levels in some hyperlipidemic individuals and has a major protective effect on cardiovascular disease. [38],[39] Moreover, it improves the glucose tolerance in some diabetic patients; it increases the wet fecal weight and reduces the caloric density in some foods. [31],[40] Dietary fiber seems also to have a positive effect on diarrhea and constipation and as a therapy of irritable bowel syndrome; it has anti-inflammatory and anticarcinogenic effects on digestive system. [41],[42],[43]


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