Soya: The king of beans

The Asian love affair with the soya bean dates back thousands of years and it is indeed loved in many, many ways.

Much has been written and discussed about the soya bean. It can be traced back to 11th Century BC when Chinese Emperor Shen Nong who named it one of the five sacred plants that included rice, wheat, barley and millet.

It was introduced to nearby countries of Korea and Japan while farmers in the US first grew it in 1829.

Asia, in particular China, remains the primary consumer of soya beans.

One of nature's finest gifts to man, the soya bean is eaten in a variety of ways.

Think boiled, fermented, pressed for oil and milk, made into various forms of tofu, beancurd skin and even used for sauce and dessert.

Soya bean products are again, used in countless recipes, limited only by the cook's creativity.

For vegans, soya bean is a major source of protein. It is considered a complete protein as it contains significant amounts of the eight essential amino acids. It is said to have the nutritional equivalent of meat and eggs.

But really, I think the popularity of soya products lies in the fact that it's easy to cook and eat.

Tracing the bean

Nutrition Society Of Malaysia recently organised a seminar titled Soy Nutrition, Trends & Market Development in collaboration with Singapore's The Nutrition Place and The American Soybean Association International Marketing.

In his opening address at the seminar, NSM president Dr Tee E Siong says soya bean makes a good protein alternative to meat as they have a complete amino acid content. However, it is not just about nutrition.

"More are recognising the functional components as well," he says.

"Soya bean contain phytochemicals which provide physiological benefits such as reducing cardiovascular heart disease, blood cholesterol and the risk of osteoporosis, hot flashes and various types of cancer.

"Available data suggests that isoflavones have direct effects on coronary vessels and studies also show that eating soya beans help reduce risk of breast cancer. But consumption should start from youth to derive the full benefits.

"People seem to have their priorities wrong," he says. "It is imperative that you take care of nutrition when young, not after retirement or sickness.

"In a study in Shanghai, women who consumed a high amount of soya consistently from adolescence had a substantially reduced risk of breast cancer. Consumption of non-fermented soya is also associated with a reduction in prostate cancer."

There have been controversial concerns about soya bean.

It was feared that the oestrogen-like effects of isoflavones may impair male fertility and cause feminine effects in men as well as affect thyroid functions, and whether soya bean milk is suitable for infants who are lactose-intolerant.

"Clinical and epidemiologic studies have shown that isoflavone does not adversely affect breast tissue but rather, is suggestive of benefits.

"There is no clinical evidence either that suggests soya protein lowers serum testosterone levels or exerts oestrogen-like or have feminising effects on men," he says, adding that there is also no evidence that soya protein adversely affects thyroid function in healthy individuals.

Gout is another health concern as soya beans contain purine. (Purines are chemicals that occur naturally in foods, especially in meat and many kinds of fish. When ingested, purines produce uric acid which form crystals in the joints, leading to gout, a painful form of arthritis).

But while whole soya bean contains a high level of purine, products such as tofu, tempeh and soya bean milk contain relatively less purine than meat.

Dr Tee is happy to note that though soya bean produce was popular with mainly the Chinese in the past, all ethnic groups today take soya products, especially tofu, as they recognise the benefits.

"For instance, yong tofu is enjoyed by the various communities and is now recommended in the Malaysian Dietary Guidelines 2010," he says.

Impact on diabetes

National University of Singapore Saw Swee Hock School of Public Health associate professor Dr Koh Woon Puay had studied the association between soya and its components (isoflavones and protein) and Type-2 diabetes.

The results support a protective role for unsweetened soya foods and isoflavones on risk of the disease. The study had used the data from the Singapore Chinese Health Study started in 1993.

"Soya-based diet is encouraged rather than isoflavone pills or extracts," she says adding that the level of sugar content must be taken into consideration.

Calcium connection

It is believed that consumption of dark green vegetables and soya products may help to maintain bone density and strength.

Though unfortified soya beans contain far less calcium than dairy milk, "studies have shown that diets high in animal protein causes more calcium to be leached from the bones and excreted in the urine and faeces". On the other hand, protein from soya beans does not have this effect.

Studies also show that those who consume large amounts of soya appear to have higher bone densities than those with a lower intake. So not only does soya offer a source of calcium but it also reduces loss of calcium from bones and promotes bone strength.

Osteoporosis is a silent condition of ageing that includes bone loss and deterioration of the bone structure. Those above the age of 40, especially women, are at greater risk.

Soya bean products that are good sources of calcium are tofu (which has been coagulated with calcium sulfate), calcium-fortified soya bean milk, whole soya beans, soya flour and tempeh.

Future for soya beans

There are different reasons, geographically, why people eat soya beans.

In Indonesia, it's functional, meaning it's affordably available to a major percentage of the population. In Japan and China, it's a heritage food and they grew up eating soya bean produce.

In Singapore, it's an indulgent item and people eat it because they enjoy it. In Malaysia, the main reason is that soya bean products are good for health, cheap and easy to get.

In a recent study on people and soya bean conducted by the United States Soybean Export Council in Southeast Asia, it was found that traditional items such as soya bean milk and tofu topped the list of soya foods consumed.

Malaysians, in particular, named promotion of bone strength and fibre content as main reasons why they eat soya bean followed by benefits to the heart, brain and development of the foetus.

But with development, more disposable income and the invasion of western diets, the younger generation (aged 40 and under) does not seem as keen on soya bean products as their parents.

Nutritious legume

SOYA bean is a species of legume native to East Asia. Soya bean is considered complete protein as it contains significant amounts of essential amino acids.

It has no cholesterol. Yes, it contains a good amount of fat but it's monounsaturated and polyunsaturated fats, including omega-3 fatty acids.

It is an excellent source of minerals including calcium, iron and zinc and phytochemicals including phytosterols, isoflavones, saponins, phenolic acids and phytic acids which are anticarcinogens.

It is high in dietary fibre and an excellent source of B-complex.

FERMENTED SOYA PRODUCTS

Tempeh, natto, nam yue, soya sauce, fermented bean paste, salted brown beans, miso.

NON-FERMENTED SOYA PRODUCTS

Soft tofu, firm tofu, beancurd skin, soya bean milk.

Debunking common myths

Myth: Cow's milk is better than soya bean milk

Fact: Soya bean milk offers the same important nutrients as cow's milk such as calcium, protein and vitamin D. It is low in saturated fat and cholesterol-free. Even better, a soya bean-rich diet will not leach calcium from bones, unlike animal protein.

Soya bean products high in calcium include fortified milk, tofu, tofu pudding and tempeh.

Myth: Soya bean is an allergen

Fact: Soya protein can cause allergic reactions in sensitive individuals but so can proteins in fish, milk, nuts, eggs and wheat. Not everyone is allergic to soya bean and surveys have indicated that allergy to cow's milk is 40 times more common than soya bean allergy.

Myth: Soya bean affects fertility.

Fact: There is no scientific evidence to indicate that eating soya products will affect fertility in women or sperm quality or quantity in men.

Soya bean does not contain oestrogen. It does, however, contain isoflavones, also known as phytoestrogens but which do not have the same effect as oestrogen on the body. Isoflavones have also been proven to support heart and bone health, minimise menopausal symptoms and reduce the risk of some forms of cancer.

Myth: Soya bean makes men feminine

Fact: Soya bean doesn't cause breast growth or reduce testosterone levels in men. A study of men who ate soya foods twice a day for three months showed no change in testosterone levels.

Myth: Soya bean protein is inferior because it comes from a plant.

Fact: Plant protein is as complete as animal protein. Soya bean in particular, contains all of the essential amino acids in sufficient quantities that the body needs.

Myth: Soya contributes to thyroid problems.

Fact: There is no scientific evidence that soya bean affects thyroid function.

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