Soy

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Types of Soy
The Soy Story

Benefits of Soy Products

What has most interested scientists in recent years is the discovery of non-nutritive phytochemicals and the profound benefits of soy on human health.

Benefits of soy include promoting heart health and healthy bones, preventing cancer and alleviating menopausal symptoms. Health-conscious people have known for decades the benefits of soy foods and that they are a fun and healthful addition to the diet.

It is widely known that soy beans contain high amounts of protein, including all essential amino acids (the only such vegetable source). Soy beans are also a rich source of calcium, iron, zinc, phosphorus, magnesium, B-vitamins, omega 3 fatty acids and fiber.

The common soy bean first became a food staple in ancient China approximately 5000 years ago.

By the year 300 BC, cultivation of soy beans and its use as food spread to Korea, Japan and Southeast Asia, and finally about 1000 years later to Europe.

In these countries, it is known from personal experience that soy products can play an important role in disease prevention. On the other hand, heavily-processed, genetically-manipulated (non-organic) soy, or overuse of soy can be unhealthy.

By sampling traditional dishes from Japan, China and Indonesia, it can be seen that soy products make up a small to moderate part of the diet.

Vegetables, whole grains, lean meats (e.g., fish), other legumes, etc. make up much of the diet. Such a balanced diet with the addition of occasional use of small amounts of soy products provides the maximum health-building and disease prevention benefits.

It is best to avoid getting sucked into any future "soy supplement hype" and stick to occasional, small intake of healthier organic soy products such as tofu, tempeh, miso, soy milk, natto, tamari and shoyu.

Types of Soy Products

Soy Product Nutrient Charts

Soy Product Benefits

High Protein Content

Traditional soy products such as tofu, tempeh, and soy milk are very high in protein. Tempeh has the highest percentage of protein of the traditional soy products providing approximately 22 grams of protein for each 4 ounce (113 gram) serving. Tofu provides approximately 9 grams of protein for a similar small serving size.

The Recommended Dietary Allowance of protein for adult males (aged 25-50) is approximately 63 grams and 50 grams for adult females (aged 25-50). Soy products can provide a significant portion of one's daily protein needs.

It is important to keep in mind, however, that the balance of amino acids (protein building blocks) in soy is not the same as meat.

Because soy foods does not have an ideal balance of amino acids, some experts recommend taking in a little extra soy foods and/or combining soy products or legumes with a whole grain dish at meals where other protein (e.g., eggs, fish) is not eaten.

The amino acids in whole grains combine well with amino acids in soy and legumes to make a more ideal balance of amino acids. If a person's diet is reasonably-balanced, however, there is usually no need to be concerned about getting enough protein.

Other legumes, nuts, and lean meats (e.g., fish) can provide are healthy sources of protein.

It is best not to rely solely on soy foods for protein.

Several recent scientific studies have shown that a regular intake of traditional soy foods may help to prevent breast cancer, prostate cancer and colon cancer.

One recent study related to soy products and prostate cancer determined that:

"..........soy products were found to be significantly protective ......... with an effect size per kilocalorie at least four times as large as that of any other dietary factor."

Researchers believe that the cancer protective effects from soy are due to the group of plant chemicals known as isoflavones, particularly genistein and daidzein.

It is theorized that these isoflavones prevent cancer by inhibiting the growth of existing tumor cells (as opposed to preventing the development of tumor cells).

One epidemiological study showed that individuals who had high amounts of soy isoflavones measured in their urine (signifying that they had a regular intake of soy foods) had approximately one-half the breast cancer risk of those who had low amount of measured soy isoflavones in their urine.

Colon cancer rates (like breast and prostate cancers) are very low in countries with higher intakes of traditional soy products.

Controlled scientific research related to soy products and colon cancer is still in the preliminary stages. One study in Hawaii found that vegetable fiber and certain vegetables and legumes (including soy products) help to lower the risk of colon cancer.

One study in Hawaii found soy product intake associated with lower risk of endometrial cancer. However, the effects of soy and legumes were limited to women who had never been pregnant and never used estrogens.

Other aspects of the diet lowered the risk as well, including vegetables grains, sea vegetables, and fruits.

Helps to Prevent Heart Disease

It is known that in countries were traditional soy products are ingested regularly, the rates of cardiovascular diseases is low. There is some research that suggests that soy foods may help to prevent heart disease by reducing total cholesterol, low density lipoprotein cholesterol, blood pressure and possibly preventing plaque buildup in the arteries (atherosclerosis). It is believed that the isoflavones from soy foods are the primary factors involved in these beneficial health effects.

May Help to Prevent Osteoporosis

One cup of tofu contains approximately 20% (204 mg) of the U.S. Recommended Dietary Allowance (RDA) for calcium intake (1000 mg) for adults 19-50 years old.

Tempeh contains approximately 15% (154 mg) of the RDA. Soy Milk is not quite as good a source of calcium according to the USDA nutrient charts.

In most countries, calcium intake is well below the RDA figures and there are little problems with osteoporosis largely because of the regular physical activity (esp. weight-bearing exercise) in these countries.

Therefore, a moderate intake of soy products such as tempeh and tofu along with regular exercise may help prevent osteoporosis.

Another factor in the possible effectiveness of soy to prevent osteoporosis may be its content of the group of plant chemicals known as Isoflavones. Several studies have suggested that the isoflavones in soy products may be a factor in helping to prevent bone loss.

In fact, one study in animals showed that soy intake may be as extremely effective in suppression of bone loss. However, preliminary results from human studies appear to indicate that the benefit may not be as great in humans.

Benefits of Soy: Healthy Bones

Osteoporosis is a disease in which bones become thin, brittle and easily broken.  Weight-bearing exercise and sufficient calcium and Vitamin D help keep bones strong.

Sodium and large amounts of protein may have a negative effect on bone health, because they increase the amount of calcium depleted from the body. Soy foods can contribute to bone strength in three ways:

  1. Replacing animal foods with soy foods may help conserve the body's calcium stores.

    • Some studies have shown that diets excessively high in animal protein cause more calcium to be leached from the bones and excreted in the urine and feces.

    • In general, protein from beans does not have this effect. Since bones are normally very dynamic - constantly losing an regaining calcium - some loss is normal.

    • However, any factor that contributes to accelerated calcium loss could compromise bone health. The extent to which protein actually affects bone health is not known and further study is needed.

    • But eating soy foods instead of animal protein may benefit the bones.

  2. Isoflavones in soy foods may actually inhibit the breakdown of bones.

    • Daidzein, one isoflavone, is actually very similar to the drug ipriflavone, which is used throughout Europe and Asia to treat osteoporosis.  In fact, ipriflavone becomes most effective when it is metabolized. One of the products of its metabolism is daidzein itself.

    • Recent studies have also shown genistein may inhibit bone breakdown and may have similar effects to estrogens in maintaining trabecular bone tissue (the spine has a high content of trabecular bone and is most sensitive to estrogen).

    • Thus, isoflavones may both stimulate bone formation and inhibit bone reabsorption, although more research is needed to identify the exact mechanism.

    • One compelling study completed by Erdman et al focused on postmenopausal women who daily consumed 40 grams of isolated soy protein containing 2.25mg isoflavones per gram of protein for six months. Researchers found that these subjects significantly increased bone mineral density as compared to the controls who were given 40 grams of casein/non-fat dry milk powder.

  3. Finally many soy foods are naturally high in calcium (some fortified with calcium because it is a good source of a particular coagulating agent). In addition, soy also contains magnesium and boron, which are important co-factors of calcium for bone health.

May Help to Prevent or Alleviate Menopausal Symptoms

There is some scientific evidence that soy products may help to prevent or alleviate menopausal symptoms. However, the research is still in a preliminary stage.

Benefits of Soy: Menopause

Symptoms that sometimes occur with menopause include night swears and hot flashes.

These are due to a loss of temperature control - one of the by-products of a slowed production of estrogen.

Because of their weak estrogen-like effects, soybean isoflavones may be an alternative way to control menopausal symptoms.

In Japan, where soy foods are commonly consumed daily, women are only one-third as likely to report menopausal symptoms as in the United States or Canada.

In fact, there is no word in the Japanese language for "hot flashes". Even though their estrogen activity is weak, isoflavones may be potent enough to reduce menopausal symptoms.

In fact, research has shown that women who ate soy flour daily experienced about a 40 percent reduction in menopausal symptoms.

Since estrogen helps protect against osteoporosis and heart disease, women are at greater risk for both of these problems after menopause. Adding soy foods or an isoflavone supplement may provide some benefit.

Finally there may be a future for soy as an alternative to hormone replacement therapy. There is much excitement about this area of study, but it's still too early to tell. However, with many women approaching menopause - and a resounding majority feeling uncomfortable about taking synthetic estrogen or hormone replacement therapy.

Benefits of Soy: Cancer

As mentioned, many of the compounds in soy have anti-cancer properties. Of particular interest is the antioxidant activity of these compounds.

Researchers have isolated two isoflavones, genistein and daidzein, and are studying the cancer prevention and treatment properties of theses compounds.

Hormone-dependent cancers such as breast, ovarian and prostate have responded especially well to a soy-rich diet or soy supplementation.

While much promise existed with this important food source, more research is required to confirm the potential far-reading benefits in the treatment of all cancers.

Probiotic Effects From Fermented Soy Products Such as Miso

Probiotics refer to friendly bacteria which contribute to the health of the intestinal tract.

Unpasturized miso contains a significant amount of healthy friendly bacteria. In addition, probiotic foods contain a "supernatant" which refers to the growth medium of the beneficial bacteria. The supernatant contains chemicals which are very powerful for inhibiting pathenogenic bacteria and fungus. It protects the probiotic bacteria from stomach acids and provides food for the bacteria to help them flourish once they reach their destination in the intestines.

A selection of the positive health effects of probiotics can be summarized with the following excerpts from "Probiotics" by Leon Chaitow, D.O. and Natasha Trenev:

  • They manufacture B-vitamins, such as biotin, niacin (B3), pyridoxine (B6) and folic acid.

  • They act as anti-carcinogenic (anti-cancer) factors, with powerful anti-tumour potentials.

  • They act as 'watchdogs' by keeping an eye on, and effectively controlling, the spread of undesirable microorganisms (by altering the acidity of the region they inhabit and/or producing specific antibiotic substances, as well as by depriving rival unfriendly bacteria of their nutrients). The antibiotics some of the friendly bacteria produce are effective against many harmful bacteria, viruses and fungi. Not the least of the potentially harmful yeasts controlled by some lactobacilli is "Candida albicans," now implicated in many health problems in people who are malnourished or whose immune systems are depleted.

  • They effectively help to control high cholesterol levels, thereby affording us protection from the cardiovascular damage which excessive levels of this nevertheless important substance can create.

  • They sometimes act to relieve the symptoms of anxiety.

  • They play a role in protecting against the negative effects of radiation and toxic pollutants, enhancing immune function.

  • They help considerably to enhance bowel function. Where bowel bacteria are absent, the function of peristalsis is impaired, and the amount of time it take for food to pass completely through the system is much increased.

  • 60 percent of the circulating female hormones such as estrogen are excreted into the GI tract in the bile.  The hormones are then, in normal conditions, acted upon by a process known as deconjugation, by bacterial enzymes such as sulphatase catalyse, before most of it (some is excreted in the faeces) is re-absorbed into the bloodstream. From there, it is sent back to the liver for reactivation into a biologically active form.

It is not necessary to ingest large amounts of probiotic foods such as miso. In fact, it may be detrimental to do so because of the high sodium content of these probiotic foods. But regular or semi-regular ingestion (3-6 days per week) of probiotic foods such as miso can be a very healthy practice.

For example, many people have a small cup of miso soup (using unpasturized miso) a few times per week.

There are other fermented probiotic foods such as sauerkraut, kefir, pickles, wine, natural and unflavored yogurt, etc.

One advantage of miso is that persons who are sensitive to fermented foods can often tolerate the ingestion of miso.

Isoflavones and Phytoestrogens

Phytoestrogens

Plants contain numerous chemical compounds (also known as phytochemicals) that are vital to their function. When it is observed that certain plants have beneficial effects such as preventing disease or curing disease, scientists attempt to discover what phytochemical or groups of phytochemicals are responsible for these positive effects. One type of phytochemical that has interested scientists is known as phytoestrogens.

Phytoestrogens are non-steroidal phytochemicals that exert weak, estrogen-like effects on the body. One group of phytoestrogen that has been observed to have and shown experimentally to exert positive effects is known as isoflavones.

Isoflavones

The most well-known isoflavones are Daidzein, Genistein and Glycitein. These isoflavones are found in soyfoods and are believed to be largely responsible for soy's ability to help prevent some forms of cancer, heart disease, and perhaps help prevent osteoporosis and menopausal symptoms. These isoflavones are found in large amounts in soy products and in much smaller amounts in other legumes.

The isoflavone, genistein, has been shown to inhibit breast and prostate cancer cell growth.

Another group of phytoestrogens found in soyfoods, lignans is also believed to have some anti-cancer effects. The isoflavone, daidzein, has been found to enhance bone formation leading scientists to believe that it may help prevent and treat osteoporosis. Genistein has been shown to prevent bone loss in animals.

Use of Soy Products

Scientists are capable of isolating the effects of some phytochemicals found in soy products. However, positive health effects from ingesting plants are almost always due to a combination of the phytochemicals in those plants.

Clinicians who have extensive experience using plants to help patients prevent and heal disease have found that there are almost always major drawbacks to giving isolated phytochemicals to patients as opposed to the giving them the whole plant (or an extract of all of the phytochemicals).

A couple of the drawbacks of using isolated phytochemnicals include:

  • Much greater likelihood of adverse reactions including subtle and detrimental long-term health problems which can appear months or years later.

  • The positive effects from the isolated phytochemical use often appear more quickly, but this positive change is often not long-lasting after the intake of the isolated phytochemical is stopped.

When an isolated phytochemical comes on the market, it is often heavily-hyped by certain organizations and by the media and then forgotten about several months or years later after the positive effects do not match the hype.

Focusing on the use of traditional soy products (tofu, tempeh, miso, natto, tamari, soy milk, shoyu) to help prevent disease rather than taking isolated phytochemicals is a wiser choice.

These traditional soy products have had centuries of use. Clinical and epidemiological evidence has shown disease prevention effects without any significant adverse effects from life-long intake.

Other Nutrients

In addition to being a good source of protein and calcium, soy products such as tempeh and tofu are moderately rich in important minerals such as zinc, magnesium, iron and selenium.

Dangers of Soy Products

A number of recent articles have been published about potential dangers of soy. A person who occasionally ingests traditionally-processed soy products (miso, tempah, natto, tofu) and otherwise has a balanced, healthy diet and lifestyle will not have to be overly-concerned with the potential dangers of soy.

However, those who eat soy regularly, especially products with heavily-processed or genetically-manipulated soy ingredients should pay close attention to the issues relating to the potential dangers of soy products.

There are ways to get the benefits of soy products and avoid the possible dangers of soy products:

  • Avoid non-organic, genetically-manipulated soy ingredients.

  • Avoid heavily-processed soy ingredients such as soy protein isolate, soy protein concentrate, hydrolyzed soy protein, texturized soy protein. These ingredients are will not provide any significant health benefits and may cause health problems as discussed above.

  • Use traditionally-processed soy products such as miso, tempeh, tofu, natto, and soy milk.

  • Use soy products occasionally. Eating miso soup several times per week and having tempeh or tofu in a dish a couple of time per week is fine.

  • Use other legumes or lean meats to get the bulk of your protein.

How to Avoid Genetically-Manipulated (GMO) Food Ingredients

In North America, all soy that is labeled "organic soy" is guaranteed to not be genetically-manipulated and not be treated with herbicides. Look for soy products and ingredients (e.g., tofu, tempeh, miso, soy sauce, soy milk, etc.) which are organic.

All other soy ingredients are almost always genetically-manipulated and herbicide-treated. The same is true for canola, corn, dairy products and potatoes.

Look for organic corn, potato and dairy ingredients at your local health food store. Check the ingredients labels carefully. It may be best to avoid canola altogether because it is rarely organic and is usually chemically-treated.

Outside of Europe and Asia it may not be possible at this time to avoid genetically-manipulated ingredients 100% of the time, but it is a good idea to avoid them when possible.

Soy Allergy and Intolerance Reactions

Soy products can cause allergic or intolerance reactions in some cases.

Other foods that commonly cause reactions include cow's milk (dairy ingredients), egg, wheat, peanut, corn and fish. Food additives, colorings and preservatives can cause adverse reactions. Artificial sweeteners and MSG can cause toxicity reactions.

Fortunately, traditional soy products do not cause allergies or intolerance reactions very often.

Heavily-processed soy products such as soy protein isolates and hydrolyzed soy proteins may be more likely to cause allergy and intolerance reactions (and toxicity effects from the MSG in the hydrolyzed soy proteins).

In addition, physicians and scientists in the U.K. believe that genetically-manipulated (non-organic) soy ingredients may be causing a significant increase in soy allergies.

If you are new to soy products, it might be a good idea to introduce them gradually to see if you react. If you suspect that you or your child may have soy allergies or intolerance, you can conduct your own test by completely eliminating soy (including lethicin made from soy) for a several days.

Then try just one soy product to see if it causes adverse reactions. Keep in mind that intolerance reactions can occur as long as 48 hours after ingestion of an offending substance.


The above opinionated views and information serves to educated and informed consumer .  The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. .It should not replaced professional advise and consultation.  A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions 

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