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Laissez
"Fare" Nutrition: Protein
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The number one
question most vegetarians get asked is " How do you get enough protein?"
Here's a quick-take on the subject, followed by the science which backs up these
assertion. |
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The Bottom Line:
Old and New Think on Protein
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Old, Outdated, Just-Plain-Wrong Think: Protein is the single most important element in our
diet, and we are always in danger of not getting enough of it. We need to
focus on it, counting grams to stay healthy. Protein from meat, fish,
poultry, milk and eggs is far superior in quality to that incomplete
vegetable protein in foodstuffs like nuts and legumes. Grains have no
protein to speak of. Vegetarians are particularly likely to become
protein-deficient, but everyone must be vigilant about taking in adequate
protein. |
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New, Accurate,
Live-Longer Live-Better Think: Too much protein is as harmful as too little, and is
linked with shorter life expectancy, increased cancer and heart disease
risk, leaching of calcium from the bones, kidney stress, and overweight.
Though high protein-diets cause momentary weight-loss, they do so at the
expense of overall health, and the weight is quickly regained once
individuals begin to eat normally (and everyone does sooner rather than
later; body and soul cry out against an almost carb-free diet). It is almost
impossible to become protein-deficient outside of famine conditions (in
which too few calories overall are ingested to support life, and those
calories derived from only one or two food sources). A varied vegetarian
diet with adequate calorie intake ensures adequate protein inherently.
Lastly, complete animal protein is not superior to incomplete vegetable
protein: animal protein merely supplies in one substance what vegetable
proteins supply in two. In fact, because of what the latter doesn't include (excess calories from fat, toxic residues, overabundance
of protein), the incomplete proteins can be considered superior.
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Probably no component of food has been so misunderstood, and so radically
reinterpreted, as protein, one of the foundations of nutrition --- and of
life itself. Most of us were taught how essential protein is; if we remember
one thing about what used to be called "Health and Hygiene Class," it was
the importance of eating enough protein. With increasing affluence, notes
New York Times writer Jane Brody, we "took to protein with such a
vengeance that now the average person in this country, rich or poor alike,
eats at least two times more protein than is really needed for good
nutrition." The cyclical popularity of high-protein low-carbohydrate quick
weight loss diets, like Dr. Atkin's Diet Revolution also boosted our
go-overboard-with-protein tendency.
What is this thing called protein? |
Vegetarian
sources
of protein:
Soyfoods
(tofu, tempeh, TVP, soy milk, "new generation" soyfoods such as "soysage",
ready-grounds, etc)
Beans & legumes (chickpeas, black
beans, lentils, kidney beans, ad infinitum), especially in combo with whole
grains
Nuts & seeds (including nut butters)
Seitan (wheat gluten)
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All
living tissue, animal or vegetable, contains protein. Much of our body,
excluding the water, is made up of one or another kind of protein: protein
supports and maintains our blood, organ and muscle components, our hair,
skin, and nails; the chemicals produced by our glands, antibodies and other
immunological factors --- all are made up mostly of protein. Protein is the
stuff children grow big on, the stuff with which our bodies knit themselves
back together after surgery, the stuff of which we're made. Small wonder,
then, that its derivation is the French proteine, or primary
substance, from the Late Greek proteios, primary, from Greek protos,
first. |
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If we are made of
protein, protein, in turn, is made of amino acids, linked long cluster-chains of
carbon, hydrogen, oxygen, and nitrogen (keep an eye on the nitrogen; it will
resurface later in this discussion --- think of it as a kind of protein
facilitator). The cookbook Laurel's Kitchen puts it beautifully: "As the
twenty-six letters of our alphabet can combine to form an unlimited number of
words, the more than twenty amino acids in the body can combine to form
countless varieties of protein, making possible a whole language whose
literature is the complex tissues of life." |
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Perhaps some of
this is a little too chemistry class to be clear. Don't worry, you can
still be well nourished without a PhD. But for those who want to understand a
little more, follow along: of the twenty amino acids required by the body, nine
of them are called "essential," because they must be brought in from outside, as
it were --- ingested. The other eleven amino acids, the body is able to
synthesize from within, given that it has the other nine. Of the nine
essentials, three, called the limiting amino acids, are truly
critical --- the other six are abundant and easily found in many foodstuffs. It
is these three limiting amino acids which really determine the completeness of a
foodstuff's usable protein. For when these three run out --- and they are the
three that are in shortest supply generally --- the remaining amino acids cannot
make new protein. (The names of these limiting amino acids: lysine, tryptophan,
and the interchangeable methionine/cystine; we will come back to them later). |
Protein-rich
foods that contain all of the essential amino acids are called
"complete"; most of them
 are in animal-based foodstuffs --- flesh, milk, eggs.
Although there is one complete protein that is plant-based (soybeans, whose
protein structure closely resembles that of milk, and anything made from
soybeans, such as tofu or tempeh) as a rule plant-based protein foods ---
legumes, grains, nuts, seeds --- contain only some of the essential amino
acids and are thus called "incomplete."
But "complete"
does not mean superior.
Animal protein is not in some way better than incomplete vegetable protein,
though we might say it is simpler: animal protein merely supplies in one
substance (an egg; a steak) what vegetable proteins supply in two (beans and
rice). The complete protein is simpler in the way that putting on a one-piece
jumpsuit is simpler than putting on jeans and a sweater; it's one thing, not
two, but either way covers you. But the proteins themselves --- made, as they
are, of the same old amino acids --- are neither inferior nor superior. When you
get down to the molecular level, an atom of carbon, hydrogen, oxygen, or
nitrogen is the same, whether its source is animal, vegetable, or mineral.
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But when we
consider the sources of protein, we can't evaluate the protein in them as
an isolated element, because it isn't: when you chow down on a steak or a bowl
of chili, you don't get just the protein, you get the whole package. Considered
this way, it is quite easy to make a judgment call on superior or inferior. Yes,
meat, fish, chicken, eggs and milk are good sources of complete protein. But are
they as healthful as a whole? Most of their calories come from fat, not
protein, and those fats are saturated. Much of this fat is both
cholesterol-containing and, in some people, cholesterol-inducing. Even
high-protein diets selected from relatively lean animal-based foods have been
linked to fat-clogged arteries, according to Jane Brody. Besides, flesh-based
foods, being higher on the food chain, also contain higher percentages of
pesticides and residues of medications fed to the animals during their raising.
(Perhaps this is why, in a study of fourteen thousand women covered recently in
Epidemiology, those who ate red meat daily --- whether beef, lamb, pork,
or luncheon meats --- had twice the incidence of breast cancer as those whose
primary protein sources were fish, poultry, and dairy).
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Vegetable-based
proteins are superior not only because of what they don't include, but
what they do.. |
That a lesser overall protein intake, derived primarily from plant-based
foodstuffs, supplies adequate protein while lowering the amount of cholesterol,
fat, and pesticide residues we consume, is incontrovertible. We would have to
say, given all this, that though animal-based protein may be complete, it is
inferior to vegetable-based proteins. Vegetable-based
proteins are superior not only because of what they don't include, but
what they do: positive elements like complex carbohydrates, minerals, vitamins,
fiber, just-being-discovered nutritional factors.
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Why, then,
does it take two or more vegetable proteins, combined, to equal the protein
in meat? Because of those limiting amino acids we discussed a few paragraphs
back. Some plant-based proteins are strong on one of these limiting amino
acids, but weak in two; some are strong in two, but weak in one. In 1971, a
groundbreaking book called Diet for a Small Planet, by Frances Moore
Lappe, pioneered the concept of protein complementarity: combining
plant-based foods so their particular amino acid strengths and weaknesses
balanced out. |
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Naturally, those new to cutting back on meat often imagine this
business of combining incomplete proteins to get complete protein to be
difficult or mathematical. In fact, it's as complicated as eating a bean
burrito or a peanut butter sandwich on whole wheat bread. You've already
done this a zillion times. Ms. Lappe's work was precise in its balancing of
this amino-acid-lacking foodstuff with that foodstuff rich in it, but the
next generation of nutritionally-based vegetarian cookbooks, like
Laurel's Kitchen, pointed out that the cook didn't have to be quite so
arithmetically adept: " In the kitchen it is enough to balance food
families, because the members of like families like grains, legumes, and
milk products share similar amino acid strengths and weaknesses." Doing
this meal to meal, and day to day, without too much precision necessary is
easy, because, again, many of the world's great dishes are just these kinds
of combinations: beans and cornbread, stir-fried vegetables with tofu over
rice, or Boston baked beans with steamed brown bread.
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Doing this meal to meal, and day to day, without too much precision
necessary is easy, because, again, many of the world's great dishes are just
these kinds of combinations: beans and cornbread, stir-fried vegetables with
tofu over rice, or Boston baked beans with steamed brown bread.
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Then, in the '90's, Dr. Dean Ornish made things even simpler and more
straight-to-the-point in Reversing Heart Disease: "You don't have to
be a scientist or nutritionist to combine foods properly. It's easy: just
eat any grains and any legumes sometime during the same day. That's all,
folks! " He goes on to say that while the ideal proportion is approximately
two-thirds grain to one-third legumes, "this is not critically important.
As long as you consume enough non-sugar calories to maintain your ideal
body weight, you will likely be eating enough protein."
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Which is how
much? The theory is a bit complex, but practice is simple, so bear with me.
First off, protein needs fluctuate according to age, body-weight,
health, general stress and situation, and from which dietary sources the protein
intake comes. However, the body itself is to a large extent able to compensate
for differing amounts of ingested protein, cleverly keeping itself at the
requisite and constant internal protein levels all the time. Laurel's Kitchen
explains:
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protein tissues themselves... are not static but in a constant state of
turnover, being continuously degraded and rebuilt throughout the day. In
this process the body efficiently recycles the nitrogen portions of the
degraded proteins for use in making new protein structures, so that none
of this critical element is lost in tissue turnover. The only nitrogen
which actually leaves the body is a small but steady amount in
sloughed-off skin, growing hair and nails, and various secretions and
excretions. The amino acids and nitrogen lost in this way must be replaced
by the protein we eat. During digestion, this protein is broken down into
its component amino acids from the turnover of body proteins to form a
common amino acid pool. The body can then draw on this pool twenty-four
hours a day to get the raw materials it needs to make new proteins for
growth and tissue repair. |
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he body's hoarding of nitrogen (remember nitrogen, the last element on
the cluster chain of which amino acids are made up?) makes this
possible. Excess protein intake
cannot be stored by the body as protein; it is either broken down and burned
for energy (a function much more efficiently and healthfully done by eating
carbohydrates) or it is --- regrettably --- stored as fat (any extra calories,
from any source, get stored as fat, although excess calories from fat evidently
do so most quickly). Typically, as this process of dealing with excessive
consumed protein by burning or storage takes place, one element of the protein,
the nitrogen, is excreted. But, if you happen to take in too little protein,
assuming, always, that your overall caloric intake is up there where it needs to
be, your body retains that nitrogen, from which it builds its own
protein, from within. |
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Given this, almost any combination of foods eaten
anywhere in the world, IF they are from a wide variety of whole foods
and IF an adequate number of overall calories are ingested, will meet
adult protein needs. |
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