Soy products have been a part of the standard diet in China, Japan,
Indonesia, and other countries for centuries. 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 ocassional 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 ocassional, small intake of healthier
organic soy products such as tofu, tempeh, miso, soy milk, natto, tamari and shoyu.
Before detailing the benefits, Soy Info Online! has provided
links to detailed nutrient compositions for each of the major organic
soy products.
Soy Product Nutrient Charts
(Click on the Asterisk -- "*" to Read the Definition of the Soy Product)
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 appoximately
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 soley on soy foods for protein.
Helps to Prevent Cancer of the Breast, Prostate, Colon and Uterus (Endometrium)
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 effecs 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.
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.
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--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. [The authors
go on to discuss how problems with the beneficial bacterial
population in the intestines caused by antibiotics (for example)
can lead to much lower levels of hormones being recirculated
into the bloodstream. This can be a major problem for women.]
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. Please see the
Cookbooks Section
for books with miso recipes.
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.
