Authors: Nina Planck
I eat mostly Stone Age foods, but in my kitchen you'll also find traditional farmed foods, including sweet potatoes, raw milk
cheese, lentils, whole grits, raw honey, and miso, a Japanese fermented soybean paste. I know we've been eating some of these
foods for "only" two or four or ten or thirty thousand years— not three million— but that's long enough for me.
Traditional and Industrial Soy Are Different
IN MY VEGAN AND low-fat days, I was sometimes wistful for chocolate pudding, peach milk shakes, and apple pie a la mode. To
satisfy my hankering for dairy, I bought soy "milk" and "ice cream." Millions of people began to eat soy foods, too— perhaps
for the same reason. In supermarkets today, the soy milk section is almost as big as the dairy department, and that's no accident.
Once soy milk appeared in the chilled dairy case, next to the milk, sales took off. Not long ago, the soy beverage was an
odd creature, a canned drink for people on funny diets. Now, dressed in gable-top milk cartons, soy beverages look much like
another kind of milk.
Long popular with vegetarians as a meat substitute, soy foods went mainstream with the rise of the "heart-healthy" diet. The
U.S. government says twenty-five grams of soy protein daily, as part of a diet low in saturated fat and cholesterol, may reduce
the risk of heart disease. Soy isoflavones are antioxidants, and its amino acids keep insulin in check. Soy may also prevent
osteoporosis, hot flashes, prostate cancer, and some breast cancers.
These health benefits are impressive, and I began to wonder if the soy foods I was eating were traditional foods by my rough
definition. Do they have a long history in the diet? Are they made pretty much the way they used to be? It turns out that
some soy foods are traditional, others less so. This is what I learned about the remarkable soybean.
In China five thousand years ago, the soybean was grown to feed animals and build soil fertility, but not for human consumption.
It turns out that we don't digest soybeans easily. In the Chou Dynasty (1134-246 BC), the Chinese learned to ferment soybeans
to make them digestible to humans, and after this discovery, various fermented foods like Japanese miso sprang up. Bean curd
was fermented, as in Chinese
sufu,
Indonesian tempeh, and Japanese
tofuyo,
or "spoiled milk."
Like all legumes, soybeans contain phytic acid, which, as we've seen, is called an antinutrient because it reduces absorption
of calcium, iron, magnesium, zinc, and other minerals.
7
Diets high in phytic acid stunt growth. Cooking reduces phytic acid somewhat, and both soy milk and tofu are cooked. But
fermentation is better; fermented tofu contains more available iron.
8
Soy also contains protease inhibitors, which interfere with protein digestion by blocking protease enzymes that break it
down. Protease inhibitors are reduced by cooking or fermentation.
9
At first the chemistry of soybeans seemed arcane to me, but the effects are important. After World War II, the United States
sent soybeans to hungry people in Japan, Korea, and Germany. When the Germans got headaches and stomach pain and lost weight,
the Americans, guessing they were biologically different from Asians, stopped sending soy. Later, U.S. scientists discovered
the necessity of fermenting soybeans— only to find that Asians knew the secret all along.
Many people think that soy provides complete protein, but that's not quite so. Soy does have all the essential amino acids,
but only trace amounts of two: cysteine and methionine. The body cannot make methionine. It can make cysteine, but only from
methionine. Only animal products contain high-quality protein, with the right amount and proportion of all the amino acids.
Soy is also said to contain vitamin B
12
, but that's misleading. The compound in soy that resembles B
12
cannot be used by the body. True vitamin B
12
is found only in animal foods, with one partial exception. Some B
12
is created during fermentation by microorganisms— which are, of course, tiny animals. Thus yeast and beer contain trace amounts
of B
12
. Vitamin B
12
is essential, but a small quantity is enough. Eating fermented soy sauce may be one reason Asians were able to survive protein-poor
diets during famines.
In the United States, the soybean was little known until the 1920s, when the government paid farmers to grow it. Animals on
factory farms eat a lot of soybean cakes, but as a raw commodity, soybeans don't fetch a very high price. With a bit of tinkering,
however, the soybean can be made much more profitable. In a remarkably short time, the food industry transformed the soybean
from animal fodder into thousands of convenience foods worth billions of dollars.
The modern soybean yields two products for human consumption: oil and protein. Rare a hundred years ago, soybean oil is now
the most popular oil in the world. In culinary-historical terms, it's an overnight sensation. Annually, Americans consume
eighteen billion pounds of soybean oil, some 75 percent of the oil they eat. Alas, most soybean oil is industrial. About 85
percent of the U.S. crop is genetically engineered, and most of it is treated with heavy doses of nitrogen fertilizer and
pesticides. Soybean oil is pressed under great heat and pressure, and the pulp is treated with solvents like hexane to extract
the last drops of oil. The oil may be washed in lye, deodorized, and bleached. It's no surprise that industrial soybean oil
emerges oxidized and carcinogenic.
10
Cold-pressed oil from organic soybeans is better; its polyunsaturated fats and vitamin E are undamaged. However, soybean oil
is rich (53 percent) in the omega-6 fat linoleic acid (LA), and as we've seen, we already eat too much LA. That's why soybean
oil is the only soy food that Barry Sears, author of
The Soy Zone,
does
not
recommend. The flavor is nothing special, either, and olive oil contains all the omega-6 fats you need.
Unusually for a bean, the soybean contains more protein (38 percent) than carbohydrate. When soybean oil is made, a great
deal of protein remains. Ingeniously, soy producers have transformed this leftover into the key ingredient in imitation sausages,
milk, and cheese. Called soy protein isolate, it's 90 percent protein. As usual, industrial production does it no favors.
Vitamins and the amino acid lysine are lost, while aluminum residue remains. Soy protein isolate does not have the FDA status
known as GRAS (Generally Recognized as Safe).
With the invention of soy protein isolate, the market for soy foods exploded, and now it's the base for chips, pasta, meatless
sausage, and dairylike foods. The challenge is making these imitation foods taste like the real thing. As fans of the tofu
stir-fry know, the naturally bland soybean is a good platform for other flavors. It can also be "beany" or bitter. Texture
is another problem: soy "cheese" is distinctly rubbery. Aware of all this, industry scientists are hard at work on soybean
hybrids and processing methods to improve soy texture and flavor. Meanwhile, industrial soy foods need a boost in the flavor
department. Typical ingredients in soy "ice cream" are sugar, corn oil, soy protein isolate, food starch, and flavoring. Fake
cheese often contains hydrogenated oils, and MSG is common in savory foods like hot dogs.
Because flavor is not its strong suit, much of the soybean's appeal rests on health claims. Evidence for some benefits of
soy seems strong. Soy isoflavones reduce LDL. As part of a diet low in refined carbohydrates, lean soy protein regulates blood
sugar and insulin. That's the message of
The Soy Zone,
by Sears, who devised a soy diet (with, I noted, added fish oil and vitamin B12) for his vegetarian daughter.
Asians have lower rates of osteoporosis than Americans, and some studies show higher bone density with soy-rich diets. Is
soy responsible? It's not clear. Phytic acid in unfermented soy reduces calcium absorption.
11
In Asia and elsewhere, traditional diets also include calcium-rich bone broth and ample vitamin D, which is vital for calcium
absorption. In fact, milk is far superior to soy as a source of calcium. One cup of soy drink has 10 milligrams of calcium,
while milk has 300 milligrams, and more of the calcium in milk is absorbed.
Because soy is rich in isoflavones (plant estrogens), it's a natural remedy for symptoms of menopause. But the research is
mixed.
12
Several recent studies have found that soy isoflavones were no better than a placebo in treating hot flashes. Moreover, large
doses are not without risk; eating 60 grams of soy protein daily for only one month disrupts menstrual cycles.
13
On soy and breast cancer, the data are voluminous, the claims competing, and the results unclear.
14
Some researchers believe soy
prevents
breast and prostate cancer, while others suggest it
causes
both. Genistein, the main soy isoflavone, can encourage cancer in breast cells, but genistein supplements are not necessarily
equivalent to the genistein in whole soy foods.
15
In 2001, researchers who reviewed studies on soy and breast cancer said, "The honest response to each of these diametrically
opposed claims is that no convincing data exist to support either claim."
16
It may be that the estrogens in soy are bad for estrogen-dependent breast cancer, but not other types of breast cancer.
Given the uncertainty, most experts recommend soy foods rather than isoflavone pills.
17
Foods may be superior because pills don't contain all the biological compounds originally in soy, but no one knows. The breast
cancer specialist Dr. Susan Love, who believes soy can be beneficial, says that "soy food and soy supplements are not the
same. Soy as food is probably safe for women with breast cancer, but the final answers aren't in yet."
18
Soy should be viewed as part of a diverse diet, not as a nutritional silver bullet. The island of Okinawa, about four hundred
miles off Japan, makes a fascinating case study for diet and disease. More Okinawans reach the age of one hundred than any
other population in the world. Islanders have less heart disease, stroke, and cancer than mainland Japanese. Fans of soy note
that Okinawans eat more soy protein than any other group: one hundred grams daily, versus forty grams on mainland Japan, and
a mere four grams in the United States.
If food does account for the Okinawans' extraordinary health (which seems likely), I'm inclined to credit the
entire
diet— including raw fish, antioxidant tea, and traditional soy foods. Islanders also eat fewer calories, twice as much fish,
and twice as many vegetables as mainland Japanese. An American wishing for the longevity of an Okinawan would need to do more
than sprinkle one hundred grams of soy protein on his cereal. It's always better to eat real foods than pop pills. Soy protein
reduces cholesterol, for example, but isoflavone supplements don't. An Okinawan proverb sums it up nicely: "One who eats whole
food will be strong and healthy."
19
In traditional Asian cuisine, soy is part of a diverse diet. Tofu is typically eaten with an animal protein such as fish broth,
which provides complete protein and reduces the effects of phytic acid.
20
Many foods, such as natto, miso, and often tofu, are fermented. There is a bewildering variety of traditional tofu recipes.
Indonesian tempeh, a chewy soy cake made with rice or millet, is quite unlike silky Japanese tofu, for example. In China,
various pungent fermented tofus, pickled and aged in rice wine, chillies, and spices, are used in specific dishes, such as
steamed pork and congee (a rice gruel).
The most famous fermented soy food is soy sauce. Traditionally, whole soybeans are slowly fermented to break down the protein
and develop a distinctive briny flavor. Industrial soy sauce is made with defatted soy protein, wheat, sugar, preservatives,
and coloring. Using defatted soybeans speeds fermentation because complex oils need not be broken down into fatty acids, but
soy sauce made from defatted soy lacks the flavor, aroma, and health benefits of the real thing.
Edamame,
an ancient Japanese delicacy of fresh, young, whole soybeans, is not a fermented soy food. The beans are merely boiled. Perhaps
young beans are easier to digest than mature, dried beans and thus don't require fermentation; I don't know. Bright green
edamame
tastes a bit like a sweet young lima bean and is delicious with salt.
TRADITIONAL SOY FOODS
Many soy foods are common in more than one Asian country. For example, fermented bean sauce is originally Chinese, but it
turns up in Vietnamese and Thai dishes. You will find the following foods in whole food shops, good grocers, and Asian markets.
•
Amazake.
Sweet, cultured rice "pudding" (Japanese).
•
Bean sauce.
Salty, fermented soybean sauce, often spicy.
•
Miso.
Salty, fermented paste of cooked soybeans, aged for a year or more (Japanese).
•
Natto.
Salty topping of fermented, cooked whole soybeans (Japanese).
•
Soy milk.
Soybeans are soaked, ground, simmered, and pressed.
•
Soy sauce.
Salty, aged, fermented condiment, best made with whole soybeans.
•
Sufu.
Fermented tofu condiment regarded as medicinal (Chinese).
•
Tahuri.
Fermented tofu (Filipino).
•
Tamari.
Liquid left after miso is made, used like soy sauce;
contains no wheat (Japanese).
•
Tempeh.
Fermented tofu cake often containing rice or millet (Indonesia).
•
Tofu.
The traditional soybean curd; may be firm or soft, grainy or silky; often fermented.
•
Tofuyo.
Fermented tofu said to be good for the stomach (Japanese).