Soya Beans
The soybean (U.S.) or soya bean (UK) (Glycine max) is a species of legume native to East Asia. It is an annual plant that has been used in China for 5,000 years as a food and a component of drugs. Soy contains significant amounts of all the essential amino acids for humans, and so is a good source of protein. Soybeans are the primary ingredient in many processed foods, including dairy product substitutes.
Uses
-
Soybeans can be broadly classified as "vegetable" (garden) or field (oil) types. Vegetable types cook more easily, have a mild nutty flavor, better texture, are larger in size, higher in protein, and lower in oil than field types. Tofu and soymilk producers prefer the higher protein cultivars bred from vegetable soybeans originally brought to the United States in the late 1930s. The "garden" cultivars are generally not suitable for mechanical combine harvesting because they have a tendency for the pods to shatter on reaching maturity.
Among the legumes, the soybean, also classed as an oilseed, is pre-eminent for its high (38–45%) protein content as well as its high (20%) oil content. Soybeans are the leading agricultural export in the United States. The bulk of the soybean crop is grown for oil production, with the high-protein defatted and "toasted" soy meal used as livestock feed. A smaller percentage of soybeans are used directly for human consumption.
Immature soybeans may be boiled whole in their green pod and served with salt, under the Japanese name edamame. Soybeans prepared this way are a popular local snack in Hawaii, and are becoming increasingly popular in the continental United States. Because of the proclaimed health benefits of soy, edamame has been featured as an ideal snack alternative in fitness and healthy living magazines such as Real Simple. Edamame is sold in the frozen vegetable section at some larger grocery stores and as a ready-to-eat snack food in many Asian delis.
In China, Japan, and Korea the bean and products made from the bean are a popular part of the diet. The Chinese invented tofu, and also made use of several varieties of soybean paste as seasonings. Japanese foods made from soya include: miso, natto, and edamame. In Korean cuisine, soybean sprouts, called kongnamul are also used in a variety of dishes such as doenjang, cheonggukjang and ganjang.
The beans can be processed in a variety of ways. Common forms of soy (or soya) include soy meal, soy flour, soy milk, tofu, textured vegetable protein (TVP, which is made into a wide variety of vegetarian foods, some of them intended to imitate meat), tempeh, soy lecithin and soybean oil. Soybeans are also the primary ingredient involved in the production of soy sauce (or shoyu).
Archer Daniels Midland (ADM) is among the largest processors of soybeans and soy products. ADM along with Dow Chemical Company, DuPont and Monsanto support the industry trade associations United Soybean Board (USB) and Soyfood Association of North America (SANA). These trade associations have increased the consumption of soy products dramatically in recent years.
-
Nutrition
-
Soybeans are considered by many agencies, including the US Food and Drug Administration, to be a source of complete protein. A complete protein is one that contains significant amounts of all the essential amino acids that must be provided to the human body because of the body's inability to synthesize them. For this reason, soy is a good source of protein, amongst many others, for many vegetarians and vegans or for people who cannot afford meat. According to the FDA, "Soy protein products can be good substitutes for animal products because, unlike some other beans, soy offers a "complete" protein profile. Soybeans contain all the amino acids essential to human nutrition, which must be supplied in the diet because they cannot be synthesized by the human body. Soy protein products can replace animal-based foods--which also have complete proteins but tend to contain more fat, especially saturated fat--without requiring major adjustments elsewhere in the diet." However, as with any dietary health claim, there are opposing viewpoints on the health benefits of soybeans.
The gold standard for measuring protein quality, since 1990, is the Protein Digestibility Corrected Amino Acid Score (PDCAAS) and by this criterion soy protein is near to being the nutritional equivalent of meat and eggs for human growth and health. Soybean protein isolate has a Biological Value of 74, whole soybeans 96, soybean milk 91, and eggs 97.
Soy protein is essentialy identical to that of other legume{pulse} seeds.. Moreover, it has the highest yield per square meter of growing area, and is the least expensive source of dietary protein. Consumption of soy may also reduce the risk of colon cancer, possibly due to the presence of sphingolipids.
-
Role of soyfoods in disease prevention
- Omega-3 fatty acids: Omega-3 fatty acids, for example, alpha-linolenic acid C18-3, all cis, 9,12,15 octadecatrienoic acid (where the omega-3 refers to carbon number 3 counting from the hydrocarbon tail whereas C-15 refers to carbon number 15 counting from the carboxyl acid head) are special fat components that benefit many body functions. However, the effects which are beneficial to health are associated mainly with the longer-chain, more unsaturated fatty acids eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) found in fish oil and oily fish. For instance, EPA and DHA, inhibit blood clotting, while there is no evidence that alpha-linolenic acid (aLNA) can do this. Soybean oil is one of the few common vegetable oils that contains a significant amount of aLNA; others include canola, walnut, and flax. However, soybean oil does not contain EPA or DHA. Soybean oil does contain significantly greater amount of omega-6 fatty acids in the oil: 100g of soybean oil contains 7g of omega-3 fatty acids to 51g of omega-6: a ratio of 1:7. Flaxseed, in comparison, has an omega-3:omega-6 ratio of 3:1.
- Isoflavones: Soybeans also contain the isoflavones genistein and daidzein, types of phytoestrogen, that are considered by some nutritionists and physicians to be useful in the prevention of cancer and by others to be carcinogenic and endocrine disruptive. Soy's content of isoflavones are as much as 3 mg/g dry weight. Isoflavones are polyphenol compounds, produced primarily by beans and other legumes, including peanuts and chickpeas. Isoflavones are closely related to the antioxidant flavonoids found in other plants, vegetables and flowers. Isoflavones such as genistein and daidzein are found in only some plant families, because most plants do not have an enzyme, chalcone isomerase which converts a flavone precursor into an isoflavone. In contradiction to well known benefits of isoflavones, Genistein acts as an oxidant (stimulating nitrate synthesis), as well as it blocks formation of new blood vessels (antiangiogenic effects). Some studies show Genistein to act as inhibitor of the activity of substances in the body that regulate cell division and cell survival (growth factors).
- Claims of cholesterol reduction: The dramatic increase in soyfood sales is largely credited to the Food and Drug Administration's (FDA) approval of soy as an official cholesterol-lowering food, along with other heart and health benefits. A 2001 literature review argued that these health benefits were poorly supported by the available evidence, and noted that disturbing data on soy's effect on the cognitive function of the elderly existed. In 2008, an epidemiological study of 719 Japanese men found that tofu intake was associated with worse memory, but tempeh (a fermented soy product) intake was associated with better memory. This study replicated other studies. From 1992 to 2003, sales have experienced a 15% compound annual growth rate, increasing from $300 million to $3.9 billion over 11 years, as new soyfood categories have been introduced, soyfoods have been repositioned in the market place, thanks to a better emphasis on marketing nutrition. In 1995, the New England Journal of Medicine (Vol. 333, No. 5) published a meta-analysis financed by DuPont Protein Technologies International (PIT), which produces and markets soy through The Solae Company. The meta-analysis concluded that soy protein is correlated with significant decreases in serum cholesterol, LDL (bad cholesterol) and triglycerides. However, HDL(good cholesterol) did not increase by a significant amount. Soy phytoestrogens (isoflavones genistein and daidzein) adsorbed onto the soy protein were suggested as the agent reducing serum cholesterol levels. On the basis of this research PTI filed a petition with FDA in 1998 for a health claim that soy protein may reduce cholesterol and the risk of heart disease. The FDA granted the following health claim for soy: "25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease." One serving, (1 cup or 240 mL) of soy milk, for instance, contains 6 or 7 grams of soy protein. Solae resubmitted their original petition, asking for a more vague health claim, after their original was challenged and highly criticized. Solae also submitted a petition for a health claim that soy can help prevent cancer. They quickly withdrew the petition for lack of evidence and after more than 1,000 letters of protest were received. In February 18, 2008 Weston A. Price Foundation submitted a petition for removal of this health claim.In January 2006 an American Heart Association review (in the journal "Circulation") of a decade long study of soy protein benefits casts doubt on the FDA allowed "Heart Healthy" claim for soy protein and did not recommend isoflavone supplementation. The review panel also found that soy isoflavones have not been shown to reduce post menopause "hot flashes" in women and the efficacy and safety of isoflavones to help prevent cancers of the breast, uterus or prostate is in question.
Soybean isoflavones are found in the following products:
ANDRO-VITO
APHRO-VITA
APHRO 40+
LIBIDO-VITA
|