Amino acids: The building blocks of protein
The smallest units of a protein are called amino acids.
Like bricks in a wall, amino acids are the building blocks
of protein. Just as glycogen is formed from the linkage
of numerous glucose molecules, proteins are formed from
the joining of numerous amino acids. There are 20 amino
acids that are required for growth by the human body. From
these 20 amino acids, there are tens of thousands of different
protein molecules that can be formed. Each protein is assembled
from the bonding of different amino acids into various configurations.
Growth hormone, for example, is a protein chain of 156 amino
acids.
"Amino acids are somewhat like letters in the alphabet.
If you had only the letter G, all you could write would
be a string of Gs: G-G-G-G-G-G-G-G. But with 20 different
letters available, you could create poems, songs, or novels.
The 20 amino acids can be linked together in an even greater
variety of sequences than are possible for letters in a
word or words in a sentence. The variety of possible sequences
for polypeptide chains is tremendous." -Eleanor Whitney
and Sharon Rolfes, "Understanding Nutrition."
Essential vs. Non-essential amino acids
Out of the twenty amino acids, the human body can make
eleven of them. These are called the non-essential amino
acids (also known as "dispensable amino acids). The
other nine amino acids are called "essential amino
acids" or (indispensable amino acids). Essential amino
acids are those which cannot be manufactured by your body
and must be supplied from your food.
Essential (indispensable) amino acids
Histidine
Isoleucine
Leucine
Valine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Non essential (dispensable) amino acids
Alanine
Arginine
Asparagine
Aspartic Acid
Cysteine
Glutamic acid
Glutamine
Glycine
Proline
Serine
Tyrosine
Why bodybuilders must eat "complete"
proteins every three hours
Foods that contain a balanced combination of all the essential
and nonessential amino acids in the exact amounts required
by the body for growth are called "complete proteins."
In order for the body to synthesize muscle, all the essential
amino acids must be available simultaneously. Any non-essential
amino acids that are in short supply can be produced by
the liver, but if an essential amino acid is missing, the
body must break down its own proteins to obtain it. To prevent
muscle cell breakdown, dietary protein must supply all the
essential amino acids. If your diet is missing any essential
amino acids, protein synthesis will be inhibited.
Carbohydrates have a storage depot in the body called glycogen.
Glycogen can be stored in the muscles and liver and then
drawn upon hours or even days later when it is needed. Proteins
cannot be stored in the body. There is only a very small
and transient amino acid pool in the bloodstream. To maintain
the optimal environment for muscle growth (positive nitrogen
balance), complete proteins must be eaten with every meal.
This explains the rationale behind the common bodybuilding
practice of eating six protein-containing meals per day
(one about every three hours.)
Protein Quality: Complete vs. Incomplete
proteins
Protein isn't just found in meat, eggs and milk. There
is also protein in vegetables, beans, legumes, and grains.
However, the protein in these foods is not considered "complete"
because it lacks one or more of the essential amino acids.
Generally speaking, proteins from vegetable sources are
lower in quality and that's the reason they are eschewed
by bodybuilders. The complete proteins are those that come
from animal sources such as eggs, milk and meat.
Many grains and legumes contain substantial amounts of
protein, but none provide the full array of essential amino
acids. Beans, for example, are very high in protein with
about 15 grams per cup, however, they are missing the essential
amino acid Methionine. Similarly, grains are lacking the
essential amino acid Lysine. It has been frequently pointed
out that combining two incomplete sources of vegetable protein
such as rice and beans provides you with the full complement
of essential amino acids. This may be true, but there's
a decided difference between simply meeting your minimum
amino acid requirements for health and consuming the optimal
quality of protein for building muscle. Combining complementary
vegetable sources of protein just doesn't cut it for the
serious bodybuilder.
Is "Vegetarian bodybuilder"
an oxymoron?
A pure vegetarian (vegan) diet is not conducive to building
muscle. One thing you will never see is a rock-hard, massive
and muscular vegan. Lacto-vegetarians (those who use dairy
products) and ovo-lacto-vegetarians (those who use eggs
and dairy products) can build excellent physiques. Bodybuilding
champion Bill Pearl is just one example. Pearl is well known
for his lifelong aversion to eating meat, but he does use
complete proteins from eggs or dairy products. With this
semi-vegetarian approach, Pearl won the Mr. America and
Mr. Universe tittles and became a legend in the bodybuilding
and fitness world.
The bottom line is that you can get fit and healthy without
consuming animal proteins, but unless you include eggs or
dairy products, you will never develop a physique worthy
of the bodybuilding stage. If a hard and muscular physique
is what you're after, then heed the advice of Robert Kennedy,
publisher of Muscle Mag International and author of "Rock
Hard, Supernutrition for Bodybuilders:"
"The bodybuilder would be ill-advised to adopt a true
vegetarian diet. You can be one of the millions who are
eating less meat and more vegetables. You may even want
to drop all flesh entirely. But is would be a mistake to
try for pure vegetarianism. Only 3.7% of Americans consider
themselves to be vegetarians, and of those only a fraction
of 1% are purists. In the bodybuilding world of champions,
that percentage is currently.... ZERO!"
Lean sources of complete proteins
Complete proteins come from animal sources including meat,
eggs and dairy products. The obvious problem with animal
proteins is that they also contain large amounts of saturated
fat. To stay lean, bodybuilders must always keep fats in
the diet low. Fortunately, fat from animal proteins can
easily be avoided simply by making the correct choices.
For example, use egg whites instead of egg yolks, lean meats
such as turkey breast and chicken breast instead of fatty
cuts of meat, and 1% low fat or non-fat dairy products instead
of whole milk dairy products. These are some of the best
sources of lean protein for bodybuilding purposes:
Chicken breast
Turkey breast
Fish
Shellfish (shrimp, lobster, crab, clams, etc)
Egg whites
Lean red meats (top round, lean sirloin, and flank)
Nonfat or low fat dairy products
Protein powders (Whey protein, for example).
The great debate; The RDA vs. the "protein
pushers"
For years a heated controversy has raged over whether or
not extra protein will boost muscle development. On one
side of the debate you have the conservative dietitians
and medical community who stubbornly insist that the recommended
Daily Allowance (RDA) is all you need to develop muscle.
The RDA's are the official government guidelines set by
the national research council. Currently the RDA for protein
is based on body weight and is set at .8 grams per kilogram
of body weight (that's .36 grams per lb. of body weight).
For a 172 lb. man that equates to a paltry 62 grams per
day. It is important to note that the RDA's were developed
for the "average" sedentary person to avoid deficiency,
not for athletes in hard training to gain muscle and strength.
In fact, the RDA handbook even says, "no added allowance
is made for stresses encountered in daily living which can
give rise to increases in urinary nitrogen output."
On the other side of the debate, you have the "protein
pushers" who claim that megadoses of protein are the
key to muscular growth. These high protein fanatics often
suggest intakes of 400-500 grams a day or more. More often
than not, the protein pushers are in some way affiliated
with a supplement company and have a vested interest in
selling you protein powder. In other cases, these high protein
advocates may be professional bodybuilders who are taking
large amounts of anabolic steroids, which can allow the
body to utilize more protein than normal.
So who is right, the conservative medical and scientific
community or the protein pushers? The answer is neither;
the optimal intake is clearly somewhere in between the two
extremes. An "optimal" protein intake for bodybuilders
is still unknown at this time and will require further research,
but one thing is for certain: The RDA is not enough to support
the added requirements for intense bodybuilding training.
Even the RDA handbook itself says, "No added allowance
is made here for stresses encountered in daily living which
can give rise to transient increases in urinary nitrogen
output. It is assumed that the subjects of experiments forming
the basis for the requirement estimates are usually exposed
to the same stresses as the population generally."
If bodybuilding isn't an "unusual stress" beyond
what is normally encountered in daily living then I don't
know what is.
What the current research says about
protein and bodybuilding
Research has conclusively proven that exercise increases
protein needs. Dr. Peter Lemon is the world's leading researcher
on protein requirements and athletes. In the journal "Medicine
and Science in Sports and Exercise" (19:5, S179-S190,1986)
Dr. Lemon writes;
"Several types of evidence indicate that exercise
causes substantial changes in protein metabolism. In fact,
recent data suggests that the protein recommended dietary
allowance might actually be 100% higher for individuals
who exercise on a regular basis. Optimal intakes, although
unknown, may be even higher, especially for individuals
attempting to increase muscle mass and strength."
Dr. Lemon's most recent research published in "Nutrition
Reviews," (54:S169-175, 1996) indicates that strength
athletes need up to 1.8g of protein per kg. of body weight
to maintain positive nitrogen balance. That's .8 grams per
lb. of body weight or almost 140 grams a day for someone
who weighs 172 lbs. This is very close to the long-held
belief of bodybuilders that 1 gram per pound of body weight
is optimal. Some studies have shown that even higher protein
intakes may be necessary in hard training strength athletes.
In one study of Polish weightlifters (Nutr. Metabolism 12:259-274),
5 of 10 athletes were still in negative nitrogen balance
even while consuming 250% of the RDA.
So much research has been done on protein and athletes
that it's amazing that so many conservative registered dietitians
and medical professionals still cling to the outdated notion
that the RDA for protein is sufficient for muscle growth.
The biggest irony is the fact that many of these "RDA
pushers" are overweight, flabby, out of shape professors,
researchers or white lab coat types. I don't know about
you, but I have a very hard time taking advice from "armchair
experts" who don't walk the walk. After years of being
criticized by the academic and scientific communities for
their "excess" protein intakes, bodybuilders today
have received their vindication; It is no longer a theory
that protein intakes higher than the RDA are more effective
for building muscle, it is now scientific fact.
Now that we've established these facts, that still leaves
one burning question: How do you determine the precise amount
of protein that is right for you? Read part two to find
out.
>>
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