引用第41楼dukeduck于2008-03-12 00:02发表的:
那为啥那些大牌子（GNC，EAS）的蛋白质产品却以乳清蛋白为主呢？很困惑
乳清蛋白的製造便宜和簡單很多的。可能這個就是主要原因。
找了一篇文章比較乳清蛋白和分離大豆蛋白。不好意思，其實找到了很久，一直沒空上來发。
Whey vs. Soy -- You've Been Tricked
Source: Elite Fitness: Online Bodybuilding Magazine
If you remember many years ago, weight gainers were the big thing and
protein powders were out! Then, in like a storm came the "low calorie"
weight gainers (yeah right!) and the criticism of the high calorie
diet. Right after this came the inundation of whey protein. Here's the
trend: promote something, then dispel it, promote it again, then dispel
it. This way, the supplement companies always have something "new" to
bring to the market. I predict that soon, there will be a resurgence in
the high calorie diet. I'm sure it will be slightly modified, but a
high calorie diet nonetheless.
Most supplement companies do not really care what the truth about
supplements really is -- they will promote what is "hot". Translation:
what has the lowest production costs, and the greatest money-making
potential. Back to protein powders -- is whey really the king protein?
And are you getting what you pay for? The answer is that you've been
misled again.
In this issue of Elite Fitness News, we'll take a close look at whey
protein and how it compares to other proteins -- soy protein in
particular. We'll look at how in many ways it is not the superior
protein that the bodybuilding magazines would lead you to believe.
We'll look at the following:
BV vs PDCAAS BV (Biological Value) vs PDCAAS (Protein Digestibility Corrected Amino Acid Score).
A brief history of Soy-Protein Isolate.
Soy Protein Isolate put to the Test
Glutamine: Which protein has the most.
Protein Concentrate vs. Protein Isolate
Soy Protein Isolate for body-builders
Soy Protein Isolate for Dieters
The Health Benefits of Soy Isolate
I guarantee that after reading this newsletter, you'll never look at
proteins the same way again. I also guarantee that the information in
this letter will save you money and help you get closer to finding the
ultimate protein source for building a hard lean muscular physique.
If you read any of the bodybuilding magazines for the last few years
now, it is hard not to notice the concerted effort that the publishers
have made to push whey protein as bodybuilding's superior protein
source. You've seen the claims and the hype, "biological value of
168--over 50% better that egg protein," "ion- exchanged," "richest
source of glutamine," and the list goes on and on. What many
bodybuilders do not realize, is that this hype is just that - hype.
Much of what you have heard about whey's superiority as a protein
source is just plain untrue. Let's take a closer look.
Most people do not realize whey protein's humble origins. Originally,
whey was a by-product of cheese production. Cheese is mostly fat and
casein. In the cheese making process, whey was a left over by-product,
and it was simply poured down the drain. Now, that was some time ago -
back then, the manufacturers thought, wouldn't it be nice if we could
find a way to sell the waste and make some money out of it. And the
stuff was cheap as could be. Maybe they thought, "we'll sell it to
bodybuilders! They'll eat (believe) anything." And the rest is history.
History has repeated itself for the other sources of protein as well,
when eggs were cheap, they were the preferred protein, now that they
are not quite the bargain they once were, they are no longer in vogue.
Later on, dairy subsidies made milk casein pricing more attractive, so
it then became the star. Then along came whey, and you know the rest of
the story.
1. BV (Biological Value) vs PDCAAS Protein Digestibility Corrected Amino Acid Score).
Several studies have been done to assess any differences in weight gain
between individuals supplementing with whey protein, soy protein, or
egg protein. SURPRISE, SURPRISE! There were NO differences whatsoever
(statistically speaking) between the effectiveness of the proteins.
Remember, all three of these proteins are designed to stimulate
growth-- albeit in chicks, calves, etc. So, is one really better than
another? Not according to the weight gained in the studies. Proponents
of whey say that it has an ultra high BV (biological value), exceeding
by far every other protein. One manufacturer even claims that their
protein has a BV of 168-- over 50% better that egg protein!
Scoring Protein by BV is the first area where the bodybuilding public
is being deceived and manipulated. Elite Fitness has researched this
topic rather thoroughly and has talked to experts in the field who work
for the actual companies which manufacture and process the raw, bulk
products. I have questioned several experts as to the quality of the
various proteins and have found a few interesting facts. First and
foremost, BV and PER (protein efficiency ratio) are OUTDATED. The
newest and most accurate measurement of a protein's quality for a HUMAN
is the PDCAAS--Protein Digestibility Corrected Amino Acid Score. A
mouthful I know, and yet it is the industry standard.
According to the PDCAAS scale, whey is not necessarily the best
protein. In fact, soy and whey are both considered a ONE (top score) on
the scale. Does this mean that both of these proteins are equal? Not at
all--I will discuss the pros and cons of each protein later in the
article. What it does mean is that either will supply the BASIC
BUILDING BLOCKS for muscle tissue growth and recuperation as well as
the next one.
2. A brief history of Soy-Protein Isolate.
The first thing that I do when a consultation client asks me about Soy
Isolate Deluxe protein is to ask them to forget whatever they have
heard about soy protein. Soy has received a bad reputation in recent
years because it is a protein source that comes entirely from soybeans.
Since soy is derived from a plant source, it has been viewed as an
inferior and incomplete protein. It also doesn't help that its two
greatest consumers in the U.S. today are vegetarians and people with
milk allergies such as lactose intolerance; not exactly the type of
people you expect to see squatting 500-lbs reps at your local gym.
Soy protein powders first came on the market as a food supplement
around 20 years ago in the form of soy protein concentrate. At that
time, soy protein concentrate was about 70% protein by weight. This
protein was loaded with carbohydrates, sodium, and had a poor amino
acid profile that made it inefficient for use as a quality muscle
building supplement.
The production and development of soy protein changed dramatically over
the following decade with the introduction of isolation. Isolation is a
method of extracting the soy protein from the beans and concentrating
it to make it far more useful to the body than the old soy concentrate.
This new product is called soy protein isolate and contained over 90%
protein.
3. Soy Protein Isolate put to the Test
This new soy-protein isolate looked fantastic on paper. Imagine a food
supplement that contains over 90% protein by weight with near zero
amounts of carbohydrates and fats. In addition, soy-protein isolate
could be manufactured for a fraction of the cost of other protein
sources. This is due to the U.S. producing more than $15 billion worth
of soybeans each year for use as foodstuffs for animals and humans. The
biggest question however was how efficiently would your body use this
soy-isolate as a protein source?
In 1989, soy protein was put to the test to see how it stacked up
against other proteins on a scale of protein quality. The most advanced
protein-quality measurement scale is the Protein Digestibility
Corrected Amino Acid Score (PDCAAS). The highest PDCAAS score possible
is 1.0. Any protein with a score of 1.0 is considered complete for use
by the human body. Soy was tested along with egg white, casein
(derivative of milk protein), beef, and a variety of beans to determine
their PDCAAS rating. Soy-protein isolate, along with egg white, whey,
and casein proteins, came back with a perfect 1.0 score. Interestingly
enough, beef scored only a .92 while kidney beans came in highest among
the beans with a .68 rating.
But what about hydrolization (breaking the proteins into smaller
fractions like "di and tri peptides") couldn't this make whey into the
superior product that it is supposed to be? What we found was that the
hydrolyzed whey promotes less nitrogen retention than a similar
non-hydrolyzed whey (a bad thing for a bodybuilder because a positive
nitrogen balance is a must for anabolic muscle gain.) As a note: the
hydrolyzed product that we studied was the BEST in the industry with a
27% hydrolization, no bitter taste, and at a cost from the manufacturer
of greater than $8.00 per pound! Rest assured, NO manufacturer is
selling a whey product where the raw materials for the protein cost
anywhere close to $8 per pound.
Consider the above and you will quickly realize that supplement
companies (who don't actually manufacture the whey but buy the raw
product from an actual manufacturer) are telling "some fibs" about whey
protein. BV of 168--ABSOLUTELY LUDICROUS! Real whey manufacturers
sometimes still use BV to grade protein, and they always rate whey
protein as a 94 BV! When you see a 168 BV claim listed on the label of
several manufacturers' whey protein, just turn your head, know you're
being scammed, and absolutely don't buy!
Now let's consider the other claims and statements about the di-and
tri- peptides, about glutamine, and about the BCAAs (Branch Chain Amino
Acids).
If hydrolization doesn't further increase nitrogen retention, then what
is the point of breaking protein into its smaller fractions like di-
and tri- peptides? There IS a good reason for hydrolyzing a protein and
having short peptides but it has nothing to do with BV/nitrogen
retention. Instead, it has everything to do with how FAST and EASY the
product is absorbed in the gut. Regular, undigested whey will be broken
down into di- and tri-peptides via enzymes in a person's gut and will
be absorbed as such. The caveat is that the whole process just takes a
little longer. Hydrolyzed products are basically only useful in baby
food or hospital situations where a person's digestive system is not
functioning optimally or when protein delivery is needed very quickly.
Is there any benefit of a hydrolyzed product for the bodybuilder? To
tell you the truth, I would have to say NO -- except possibly for the
benefit of having a quickly absorbed protein immediately after a
workout to ensure the muscle tissue is flooded with nutrients in a
timely manner albeit with a nitrogen penalty. Interestingly, this
entire argument about hydrolized protein is academic as it is not
currently sold on the market. Here's why. One, the cost of hydrolyzed
whey is outrageous and two, its taste is ABSOLUTELY HORRIBLE. Trust me,
if you're want to induce vomiting, just take a little hydrolyzed whey
protein!
4. Glutamine: Which protein has the most.
Isn't the claim true about whey having significantly higher amounts of
glutamine and BCAAs? Sorry, but NO! Whey does have the highest amounts
of BCAAs of any protein but NOT SIGNIFICANTLY higher amounts. When it
comes to the amounts of glutamine, soy beats whey hands down. For every
100 grams of protein, whey has 20.1 grams of BCAAs and 4.9 grams of
glutamine. Maybe to your surprise, soy has 18.1 grams of BCAAs and a
whopping 10.5 grams of glutamine! Again, we have been lied to and
deceived.
5. Protein Concentrate vs. Protein Isolate
Most companies are selling whey protein concentrate (WPC) and saying
that their product is whey protein isolate. Ion exchange protein really
doesn't mean anything in terms of the quality of the protein powder as
a whole! Any high quality, pure protein will be labeled an ISOLATE and
this is what you MUST look for. A true ion-exchange process CAN yield a
good isolate but it is not the only process available for getting a
superior whey protein. An isolate will have very little fat and lactose
and will be about 90% protein (the protein fractions are "isolated"
from the rest of the material).
On the other hand, a WPC made through protein filtration is vastly
inferior to an isolate with about 7% fat and lactose and only 75%
protein (The actual protein in WPC is usually pretty good, but who
wants to deal with all of the fat and lactose?) Interestingly, WPC
costs less than half of what an isolate costs. Unfortunately, both
products look and taste about the same so it becomes very hard to know
what you have--you basically have to trust the manufacturer (supplement
company) of the particular product.
Here's the picture--the industry through various articles in muscle
magazines touts the benefits and characteristics of a whey protein
ISOLATE and turns around and uses a CONCENTRATE. Tell me, who's the
wiser? The supplement companies, that's who, and they're a whole lot
richer to boot! Some manufacturers will put 98% WPC in their product
and then put in 1% of a hydrolyzed product (remember this tastes
horrible!) and 1% of an isolate. Then, they can legally claim all types
of stuff on their label-- di and tri peptides, ion-exchange, blah,
blah, blah!
What about the other available proteins--egg, casein, and soy? How do
these compare? First, let me state that all of the above proteins are
decent if processed correctly. Each will provide the body very
efficiently with the protein that it "needs". I would definitely stay
away from casein and egg white. Casein has been shown to have
detrimental effects on a person's cholesterol profile and egg white
protein tastes poorly, is expensive, and consists of about 10%
carbohydrates.
Before you say it, I know your response--"That's all wonderful, but
what is the best protein for me, a bodybuilder/weightlifter?" If you
were to use any ONE protein source then I would have to say that it's a
toss up between a soy isolate and a whey ISOLATE (you know, the one
that no one can buy.) WPC provides a good protein; however the
accompanying fat and carbs is something you do not want. If I had a
choice, I would pick a soy isolate. A soy isolate is inexpensive, has
the highest score on the PCDAAS, is very soluble if instantized, is
extremely bland (a good thing), IMPROVES kidney function (unlike any
other protein), is anticarcinogenic, is anti-estrogenic, lowers LDL
(bad) and raises HDL (good) cholesterol, IMPROVES THYROID FUNCTION,
etc, etc--the list goes on and on. But best of all, unlike whey
isolate, pure soy isolates exist.
6. Soy Protein Isolate benefits for Bodybuilders
Animal research suggests some great advantages of using soy protein
isolate as a bodybuilding supplement. Research has shown that the
isoflavone daidzein found in soy-protein isolate might have a gender
specific normalizing effect on sex-hormone production. Lab animals
experienced testosterone and growth hormone excretion as well as muscle
growth in males, while the female animals experienced a decrease in
these hormones and fat loss.
Daidzein is a key isoflavone found in soy that acts as a potent
phyto-estrogen. It is structurally a very weak "pseudo-estrogen" (about
1000 times weaker than the body's primary estrogen estradiol). This is
good news to the bodybuilder because weak estrogens like daidzein will
compete with stronger estrogens like estradiol for available receptor
sites to "bind" to. By binding to the receptor sites daidzein then
"blocks" the stronger estrogens from binding to and activating receptor
sites. With the daidzein isolflavone attached, estrogen receptor sites
remain inactive. This inactivity further minimizes the negative effects
of estrogen in the body. Many researchers believe this effect is the
reason soy protein is linked to a reduction in the risk for many forms
of breast, endometrial, and prostate cancer. This mechanism works
similarly to the prescription drug Nolvadex (tamoxifen citrate)--an
anti-estrogen staple in the bodybuilding community.
Research also indicates that the soy-protein isolates may reduce
nitrogen loss and keep you in a positive nitrogen balance to better
facilitate muscle growth. The human body can only repair and build
muscles when it has a positive nitrogen balance.
Of particular interest to the bodybuilder is Soy Isolates high
concentration of the amino acids glutamine and arginine. These two
aminos are extremely important to a body builder for their ability to
release growth hormone, aid in immune system functions, and for their
ability to speed muscle cell recovery.
Glutamine (per 100g)
Soy
10.5g
Milk Protein
8.8g
Whey
4.9g
Many bodybuilders understand the importance of the essential amino acid
L- glutamine to their muscle building supplementation. What many
bodybuilders don't
know is that soy protein isolate has the highest concentration of
glutamine among protein sources-over twice that of whey protein! (7)
Glutamine has been used for years in hospitals to speed muscle cell
recovery and improve maintenance of muscle mass during periods of
starvation, infection, and exercise trauma. (8) Glutamine
supplementation has been shown to promote muscle glycogen accumulation,
which has been linked to an increase in muscle protein synthesis. (10)
Glutamine has also shown the ability to increase muscle cell volume
through the process of cellular hydration. (11) Glutamine
supplementation in as little as 2 grams per day has been shown to
increase plasma growth hormone levels. This increase in growth hormone
has been shown to help shift the fuel for muscle from glucose to fatty
acids. (9) Research has suggested that a bodybuilder should consume
between 8 - 15 grams of glutamine each day. Supplementing 3-5 grams of
glutamine 3 times per day has been shown to elicit a positive response
without stimulating the excretion of glutamine in the urine.
Arginine (per 100g)
Soy
7.6g
Beef
6.3g
Egg
5.8g
Cassein
3.7g
Whey
2.9g
L-Arginine is another important amino acid with respects to body
building. Arginine plays several roles in the body such as fighting
mental and physical fatigue, but its
main job is to assist with growth. This amino acid promotes the release
of two highly anabolic hormones, insulin and growth hormone. Arginine
promotes gains further by assisting in recovery from post workout
muscle trauma through its ability to speed tissue healing. This amino
acid aids in the detoxification of the liver by removing ammonium from
the body. Arginine has also shown the ability to lower LDL cholesterol
and triglyceride levels in the blood. Arginine is used in the medical
treatment of angina, congestive heart failure, male infertility and
wound healing. Soy isolate protein contains higher amounts of this
important amino acid than any other protein source.
As a hard training bodybuilder, your body needs protein every 2 -2 1/2
hours even if you may not think you need it. The human body does not
store protein long term as it does for fat and carbohydrates. Instead,
your body holds amino acids in three pools that provide the body's
necessary protein for fuel. These pools are constantly in a state of
flux and are replenished either from dietary protein or the breakdown
of muscle. It is extremely important to keep these amino acid pools
topped off through the feeding of protein every 2 - 2 1/2 hours. When
feeding stops, there is a fall in protein synthesis and a rise in
protein breakdown. This translates into a loss of lean body mass after
extended periods without protein.
7. Soy Protein Isolate for Dieters
For years, bodybuilding gurus have recommended the use of soy protein
for pre-contest bodybuilders who need to shed body fat while keeping as
much lean muscle as possible. Normally when the body is forced into a
low calorie diet program, it reacts by slowing down your metabolic
rate. This will make it increasingly more difficult to lose body fat.
Soy-protein isolate helps lessen this effect through several different
pathways. First, soy-protein isolate has been found to enhance
endogenous production of thyroid stimulating hormone (TSH), thyroxin
(T4), and triiodothyronine (T3). Thyroxin is the main player in the
regulation of your metabolic rate. The more thyroxin you have the
faster your metabolism will be. A faster metabolism insures that more
of the food you eat will be used as fuel and less will be stored as
fat, an important advantage to any dieter.
Another way soy accelerates fat loss is with its unique concentration
of amino acids. Soy-protein isolate has the highest concentration of
amino acids in what is called the "critical cluster". This cluster of
amino acids contains the three branch chain amino acids (BCAA's) and
two essential aminos - glutamine and arginine. These critical amino
acids help a bodybuilder spare muscle while losing body fat during a
pre-contest diet. Any time you diet, your body tries to break down
muscle glycogen in an effort to provide the body with more calories. In
fact, your body will often try to use broken down muscle for fuel
before it uses stored body fat. This is called muscle catabolism or
muscle breakdown. These three branch chain amino acids are the first
amino acids that are used for fuel when your body begins muscle
catabolism. If you have a high amount of these branch chain amino acids
in your diet, your body will first use these for fuel before it breaks
down your stored muscle.
8. The Health Benefits of Soy Isolate
Now that we know that soy is a quality protein source, what health
benefits can soy protein bring to its consumer? The intake of soyfoods
has long been associated with a reduced risk for certain cancers.
Research has suggested that phytic acid and protease inhibitors, two of
the nonnutritive compounds in soybeans, contribute to the observed
anticarcinogenic effects of consuming soy. (1) Residents of the United
States and the United Kingdom, as a whole, consume the smallest amounts
of soyfoods but have the highest instances of breast and prostate
cancer. Japanese residents in comparison are the largest consumers of
soyfoods and have the lowest instances of these cancers. (3)
Researchers point to the isoflavones genistein and daidzein, which are
found exclusively in soy and soy protein isolate, as the major
components behind soy's anti-carcinogenic effects.(2)
Soy protein isolate has shown the ability to promote bone health, which
in turn aids in the prevention of Osteoporosis. Osteoporosis is a
chronic disease characterized by a decrease in bone density, which
results in abnormally porous and fragile bones. It has been suggested
that a high protein diet may increase the excretion of calcium in the
urine, which can lead to this health condition. Studies have shown that
not all proteins have the same effect on calcium excretion. Compared
with animal protein, soy does not result in an increased loss of
calcium in the urine thus promoting a more optimal calcium balance. (4)
In addition, the isoflavones in soy protein have been shown to increase
both bone mineral content and bone mineral density which will improve
the health of abnormally porous bones.(5)
Soy protein isolate has shown the ability to effectively lower LDL
cholesterol and triglyceride levels in the blood. Experts agree that
these cholesterol-lowering effects can be achieved through the
consumption of as little as 25 grams of soy isolate protein each day.
The experts point to the high levels of the amino acid arginine for
this lipid lowering effect. (6) LDL cholesterol is one of the primary
factors behind progressive atherosclerosis. This medical condition is
caused by the progressive build up of plaque that clogs blood flow in
the arteries.
Soy protein has also shown the ability to improve kidney function.
While scientists agree that the high protein intake of bodybuilders is
necessary for proper muscle building and repair, they also agree that
this diet will place additional stress on the kidneys. Studies of both
humans and animals have shown that soy proteins filter more easily in
the kidneys thereby reducing their workload. In 1993, a study was
performed on the Romanian Olympic swimming and rowing teams. In this
study, the athletes were supplemented with 1.5 grams per kg of
bodyweight of soy protein along with their dietary protein (2 grams per
kg of bodyweight) per day. This additional protein showed no
detrimental effects on kidney function and actually showed from 5 to 46
percent improvement in kidney function.
References
(1)(2) Messina M, Messina V. Increasing use of soyfoods and their
potential role in cancer prevention. J Am Diet Assoc 1991;91:836-840
(3) American Cancer Society. Cancer Facts & Figures-1996.
(4)(5)(6)Ross PD. osteoporosis: Frequency, consequences and risk factors. Archives of Internal Med 1996's 156.1399-1411.
(7)(8)(9) Bulus, N., Pysysiological Importance of Glutamine. Metabolism Vol.38, No.8, August 1989.
(10)(11) Parry-Billings, M. Effects of changes in cell volume on the
rates of glutamine and alanine release from rat skeletal muscle in
vitro. Biomedical Journal, 276, 1991.
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发表于 2008-4-15 22:46:45
这可是人体正常代谢产物啊……
.......
发表于 2008-4-16 17:59:44
