What are the health benefits of soy?

Soy is one of the healthiest foods on earth. A complete review of all the benefits could easily fill a large book. Soy's key benefits are related to its excellent protein content, its high levels of essential fatty acids, numerous vitamins and minerals, interesting phytochemicals such as isoflavones and saponins, and dietary fiber.

The soybean contains a wealth of nutrients and phytochemicals, that are tied to an impressive array of medical benefits:

Decreases symptoms of menopause

The soy isoflavones products appear to decrease the symptoms of menopause, especially hot flushes. More information about isoflavones and menopause.

Reduces risk of certain cancers

Using soy products appears to decrease the risk of breast cancer. Soy products may also decrease the risk of colon and prostate cancer. The anti-cancer action of tempeh is attributed to the isoflavones. The isoflavones have antioxidant properties and help to prevent to oxidation of DNA. Isoflavones also seem to reduce the growth rate of cancer cells.

Rich in healthy soy protein

Soy products are excellent vegetable sources of protein. Most current health recommendations suggest limiting animal protein, so substituting soy for chicken, beef, or pork makes sense. Compared to all other beans, soybeans have the highest amount of protein. In fact, 38% of the soybean's edible weight is soy protein, with the rest coming from carbohydrate and fats. The soy protein contain all the essential amino acids!

Free from saturated fat

Soy products are free of the saturated fat implicated in many health problems. Soy is also cholesterol free.

Builds stronger bones

Isoflavones in soy appear to increase the bone mineral content of post-menopausal women, decreasing the possibility of osteoporosis. More information about isoflavones and osteoporosis. The soy isoflavones are responsible for the bone protection but also, the recplacement of animal protein with vegetable or soy protein improves bone health.

Lowers cholesterol

Soy products appear to lower total blood cholesterol and LDL levels at about the same rate as decreasing fat in the diet. Twenty-five grams of soy protein is thee recommended daily consumption by the FDA. The approved health claim states: 25 grams of soy protein daily, in a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. Many food products containing soy protein advertise this claim on the label.

Mild for kidney

People with reduced kidney function--such as those with diabetes who have nephropathy--can benefit by replacing animal protein with soy protein.

Soy Saponins

Many health benefits of soybeans are attributed to their isoflavones but soy saponins, which are less studied, may also play an important role. Tempeh and other soy products, except soy protein extracted with alcohol, contain high levels of saponins. Raw soybeans contain between 2 and 5 g saponins per 100 g. Saponins are glycosides of steroids, steroid alkaloids or triterpenes found in many plants such as asparagus, soybeans, quinoa, olives, grapes and many herbs including ginseng and soapwort. When dissolved in water they form a stable soapy froth. This can easily be observed when you add water to soybean grits (see pictures above). Because of the presence of both a hydrophilic (sugar) and hydrophobic (steroid) they act as emulsifiers and foaming agents. Soy saponins are divided in 2 groups: group A saponins have and undesirable astringent taste, typical for some soy products, and group B saponins have the health promoting properties. The soybean germ contains most group A saponins, whereas group B saponins are found in the both the soybean germ and cotyledons. The soybean hulls, which are removed during the tempeh production, contain little saponins. Some types of saponins are poisonous but the ones found in soybeans and tempeh are eatable and actually possess health benefits.

Health Benefits of Soy Saponins

Soy saponins may contribute to cholesterol lowering by increasing bile secretion and may reduce the risk of colon cancer.

Cholesterol Reduction - Already in 1979 Potter et al discover the cholesterol lowering property of soy saponins. The ability of saponins to form emulsions or micelles with bile salt in the intestine probably explains their cholesterol lowering activity. Bile salt forms small micelles with cholesterol facilitating its absorption. Because soy saponins bind with bile salt, the absorption of cholesterol is reduced. Some saponins form insoluble complexes with cholesterol, resulting in inhibition of absorption cholesterol.

Anticancer - Scientific studies have illustrated that saponins can lower the risk of colon cancer. Cancer cells also need cholesterol to grow and saponins bind cholesterol rich cancer cell membranes, thereby limiting their growth. A study by Roa et al published in The Journal of Nutrition (1995, 125, 717s-724S) concluded that saponins may help to prevent colon cancer.

Inhibition of HIV - The Japanese study entitled "Inhibitory effect of glycosides like soy saponins on the infectivity of HIV in vitro" and published in AIDS (1989 Oct) concluded that soy saponins, especially saponin B1, may have inhibitory activity against HIV infection. It should be stressed that this was an in-vitro study using cultured cells and that the consumption of soy saponins is not a medicine to cure HIV.

Source : http://www.tempeh.info/health/soy-saponins.php

Isoflavones in Soybeans

What are isoflavones?

Isoflavones are phytochemicals, which are compounds found only in plants. They are also a type of phytoestrogen that resembles human estrogen in chemical structure yet are weaker. By mimicking human estrogen at certain sites in the body, isoflavones provide many health benefits that help you to avoid disease. Isoflavones are found in soybeans, chick peas and other legumes. However, soybeans are unique because they have the highest concentration of these powerful compounds.

Health effects of isoflavones

Lower cancer risk - Epidemiological studies have suggested that Asian diets may provide protection from several cancers, including those of the breast, prostate gland and colon. The action of isoflavones as weak estrogens allows them to bind to estrogen receptors and block some of the detrimental effects of estrogen - such as promotion of cancer cell growth. Tamoxifen, a prescription drug for treating breast cancer, is though to act as an anti-estrogen by binding to the estrogen receptor and "blocking" the growth-promoting effects of estrogen in cancer cells. Women using tamoxifen have a lower incidence of breast cancer and a 30-40% reduction in breast cancer cell growth rate. The isoflavones in soy are chemically similar to tamoxifen and, therefore, may also reduce the risk of hormone-dependent cancers via the same "estrogen-blocking" mechanism.

Improved bone health - Isoflavones consumption has been shown to reduce bone loss and slow calcium loss in an animal model of osteoporosis, suggesting a possible beneficial role in preventing osteoporosis in humans. In addition, soybeans contain a relatively high calcium content. It is also interesting to note that soy protein seems to cause less loss of calcium from the body compared to other dietary sources of protein, which may promote calcium loss and bone breakdown at high levels. Ipriflavone, a synthetic isoflavone drug prescribed in Europe, is metabolized in the body into daidzein, and has potent effects on reducing bone resorption in post-menopausal women.

Relieves menopause symptoms - Soyfoods which contain isoflavones may help in the treatment of menopause symptoms. In women who are producing little estrogen, phytoestrogens may produce enough estrogenic activity to relieve symptoms such as hot flushes. From an epidemiological point of view, it is interesting that in Japan, where soy consumption is very high, menopause symptoms of any kind are rarely reported.

Lowers cholesterol- Isoflavones possess anti-oxidant action, and not only help to decrease the bad LDL cholesterol, but also increase the beneficial HDL cholesterol.