The Humble Soya Bean
By Prof. Shirani Ranasinghe
Soy protein is the potent protein found in soybeans, popular with individual’s world overfor its ability to replace animal proteins to suit allpalates. The humble soybean is generally classified under the leguminous family, which includes beans and dhal, and is considered a legume with the highest level of protein and fat.
Since it is of plant origin, it contains no cholesterol, is 95% digestible and is low in saturated fat – infamous for its negative impact on health. Not only this, soybeans are the only vegetable food that contains all essential amino acidsas well as fiber, iron, calcium, zinc and B vitamins. Due to all these traits,Soy protein has received increased attention in recent years amongst consumers, researchers and the media.
Today, the food market contains numerousfood products that contain soy protein, such as TVP, Tofu, soya milk etc. Nutritionists have found that individuals following a habitually health-conscious lifestyle such as those who do not over indulge in meatbut substitute it with fish or are vegetarians or vegansare more likely to consume soy foods than the average person. Itreduces serum concentrations of total cholesterol, low-density lipoproteins (LDLs), and triglycerides, bringing down the risk of coronary heart disease and bears enormous potential to lowerLDL cholesterols and increase high-density lipoproteins, vasomotor tone changes and arterial wall functions.
Optimum daily intake
A person needs to consume about 25 grams of soy protein or more each day for optimum positive impact. Twenty-five grams of soy protein equals 11⁄4 cups of tofu, 1–2 cups of soymilk, or 28 grams of soy flour. Individuals are also encouraged to read food labels in order to verify a particular food’s soy content.
Role in maintaining blood glucose levels
With the presence ofIsoflavonesin soy products, soya proteins helpcontrol high blood glucose lipid levels and reduce body weight. Further, it enhances the insulin levels of an individual in order to maintain healthy blood glucose and lipid levels. These characteristics may be useful to both non-diabetic and diabetic persons in the control of obesity and blood sugar.
Role in preventing Cancer
It is widely believed that when a person replaces animal origin foods by plant origin foods, he increases his natural protection against cancer. Genistein, one of the phytochemicals found in soy is responsible for this reduced risk of cancer. Genistein blocks cancer development by preventing tumors from creating blood vessels which would provide nourishment for the growth of cancer mass. Numerous scientific studies have shown that one serving a day of one cup of soymilk, 1⁄2 cup of tofu or soybeans is effective in doing so.
Impact on menopause
Phytoestrogens present in soya protein are currently being researched to determine their usefulness in acting like synthetic estrogen to protect women from bone loss and in maintaining a healthy heart during menopause. Results were especially significant for women who did not receive hormone replacement therapy following menopause.
Benefits of soy for those preferring alternative diets
Vegetarians and vegans follow a dietary pattern that is lacking in vitamin B12, found in animal protein. Use of fermented soy products is one way to obtain this essential vitamin daily.
Nourishing new born babies with special medical conditions
A new born baby depends exclusively on breast milk for the first six months. Usually the lactose sugar found in breast milk is digested by the enzyme lactase which is secreted from the cells of the small intestine of the baby. Infants born with this lactase deficiency or those put on a vegetarian diet benefit greatly from the use of soy-based formulas.
Additionally, infants who are recovering from episodes of diarrhea may be given soy formula to facilitate their recovery. These soy-based formulas meet an infant’s growth and development needs. However,soy-based formulas are not recommended for pre-term infants weighing less than 1,000 grams and for infants with low birth weight as a means for preventing or managing colic or gastro- enteritis.
In summary,Soy protein products offer multi-fold benefits to those across all ages and lifestyles.They improve diet and cardiovascular status, prevent certain types of cancer, improve health following menopause, reduce or prevent obesity and offer a wider number of options for food diversity.
(Prof. Shirani Ranasinghe is a senior professor in Biochemistry at the Faculty of Medicine, University of Peradeniya)