Essential Amino Acids
The essential amino acids are those specific amino acids that you need
to consume in your diet because your body doesn’t naturally make
them. If you slept through high school biology, remember that amino
acids are the building blocks of protein. So for any given protein that
you consume, whether it be beef, chicken, or beans, the amount of each
specific amino acid differs. Most plant sources of protein for example
do NOT have enough of the essential amino acids; that’s why they
are incomplete proteins. And that’s why most athletes are carnivores.
Conversely, the non-essential amino acids are made by your body; therefore,
you don’t necessary need to consume them in your diet. Though
if you consume meat or milk-based proteins, then you will always get
a mix of essential and non-essential amino acids.
Keep in mind not to confuse ‘non-essential’ with ‘unimportant.’
Just because for instance an amino acid is made by your body (for example:
glutamine), it does not mean it is not important. On the contrary, even
the non-essential or conditionally essential amino acids are important
for your body’s normal functioning.
For us biologists, the word ‘essential’ denotes those things
that you need to consume in your diet because your body can’t
make them. If you take man’s-best-friend, those four-legged canines
for instance produce their own vitamin C. That is why you don’t
see dog food that is ‘fortified with vitamin C.’ They make
their own. But for us Homo sapiens, we don’t make vitamin C naturally,
so we need to get it in our diet. If you don’t understand the
difference between ‘essential’ and ‘non-essential’
by now, then clearly you’re in dire need of a tutor.
So what are the essential amino acids or EAA?
Of the 20 amino acids that are used to form proteins, 9 are essential
or indispensable; meaning that you need to consume them in your diet
because your body does not normally make them. (See Table 1)
Table 1 - Essential Amino Acids
1. Phenylalanine
2. Valine
3. Tryptophan
4. Threonine
5. Isoleucine
6. Methionine
7. Histidine
a. (arginine)
8. Lysine
9. Leucine
Note: A mnemonic device to remember the EAA is: PVT TIM HaLL (or Private
Tim Hall). Arginine is needed for growth in children but isn’t
essential in adults; thus, some call it ‘conditionally’
essential.
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Now the question of whether it is better to consume meat versus plant
based proteins is an interesting one. But let’s face it, if you
want inferior protein, eat plants. If you want the best protein sources,
consume animal-based proteins such as milk, eggs, meats and fish. As
a simple point of comparison, look at Figure 1 comparing the amount
of each EAA in an equal serving of chicken versus beans. There is just
no comparison. Chicken wins! It’s would be like putting Chuck
Liddell in the ‘Octagon’ with Paris Hilton. Not a pretty
site.
Note: the abbreviations for the amino acids are as follows:Phe -
Phenylalanine, Val - Valine, Thr- Threonine, Trp - Tryptophan , Ile-
Isoleucine, Met - Methionine, His - Histidine, Lys - Lysine, Leu - Leucine
You’ll notice that the branched-chain amino acids (BCAA), which
are popular among bodybuilders and other athletes, are essential (valine,
leucine, and isoleucine). The BCAA deserve special mention especially
because of their popularity. During long-distance type exercises such
as marathon running, branched-chain amino acid (BCAA) breakdown could
lead to an increase in the blood tryptophan/BCAA ratio. By affecting
this ratio, some scientists believe this leads to an early onset of
'central fatigue'. In plain English, your head just starts to feel really
tired. To offset this, sports nutritionists often suggest consuming
BCAA during exercise.
But the beauty of the EAA is not in just the branched-chain amino acids,
but in their combination as a whole. In a study from the University
of Nebraska, scientists studied a group of women who consumed either
18 grams of EAAs or placebo daily for 6 weeks. Each woman performed
a split-routine, multiple-set weight training regimen three times weekly
as well as aerobic training three times weekly for 20 minutes per session.
They discovered that time to exhaustion on a treadmill improved more
in the EAA group (+12%) versus the placebo group (+4%).1
In an elegant study from deep in the heart of Texas, scientists compared
the anabolic response of consuming an 6 grams of the essential amino
acid plus 35 grams of carbohydrate (in the form of table sugar) cocktail
before versus after heavy resistance exercise.2 For the sake of simplicity,
I’ll call this EAA plus sugar ‘EAC.’ Six healthy subjects
completed an exercise bout of 10 sets of 8 reps of the leg press (80%
of 1-RM), and 8 sets of 8 reps of the leg extension (80% of 1-RM). The
rest interval was about 2 minutes with the total exercise time roughly
45 minutes.
So what did they find? When they examined phenylalanine uptake across
the leg (as a measure of muscle protein accretion or anabolism) they
found that over a 3-hour period, taking the EAC before exercise resulted
in a net phenylalanine uptake that was about 160% greater when compared
to taking the EAC post-exercise. Meaning, the anabolic or growth promoting
response was 160% greater if you consumed the EAC before versus after
exercise. But they also found that taking EAC after exercise produced
a great anabolic response; however, it just quite wasn’t as high
as taking the stuff before training.
So what’s the take-home message from this complicated story? First,
consuming essential amino acids definitely promotes an anabolic response
when taken before or after resistance exercise. The anabolic response
just happens to be greater if you consume the essential amino acids
prior to exercise.
So if you’re a competitive athlete, it’s best that you consume
essential amino acids (or the equivalent in mixed protein [about 40
grams of whey protein for instance] prior to exercise. However, some
individuals prefer not to consume anything prior to training. If that’s
the case, a post-workout mix of protein (or amino acids), carbohydrates,
and fat (small amount) will assist you in the recovery process. Consuming
carbohydrates and protein stimulates insulin secretion from the pancreas.
Insulin is what we science types call a ‘storage’ hormone
and it promotes the uptake of amino acids and glucose into the muscle
cell as well as stimulates enzymes responsible for muscle glycogen resynthesis
(i.e. helps replenish fuel stores in muscle).
Table 2. Essential Amino Acids – What you should know
| Amino Acid | Abbreviation | Primary Function | Commonly consumed dosage for sports | Food Sources** |
| Isoleucine* | Ile | Alleviates protein breakdown; used best in combination with Leu and Val | 2.5 grams (as part of a 10 gram serving of branched-chain amino acids) | Eggs, fish, lentils, poultry, beef, seeds, soy, wheat, almonds, dairy |
| Leucine* | Leu | Alleviates protein breakdown; used best in combination with Val and Ile; important regulator of protein synthesis | 5.0 grams (as a part of a 10 gram serving of branched-chain amino acids). | Eggs, fish, lentils, poultry, beef, seeds, soy, wheat, almonds, dairy, beans, brown rice |
| Lysine | Lys | Insures the adequate absorption of calcium; helps form collagen ( which makes up bone cartilage & connective tissues) | Not applicable;it is best to consume whole proteins from animal sources to get sufficient lysine. | Fish, eggs, dairy, lima beans, beef, soy, yeast, potatoes |
| Methionine | Met | Is a principle supplier of sulfur which prevents disorders of the hair, skin and nails | Not applicable; it is best to consume whole proteins from animal sources to get sufficient methionine | Fish, eggs, dairy, beans, beef, garlic, onion, lentils, soybeans |
| Phenylalanine | Phe | Used by the brain to produce Norepinephrine, a chemical that transmits signals between nerve cells and the brain | Not applicable; it is best to consume whole proteins from animal sources to get sufficient phenylalanine. | Dairy, almonds, avocados, lima beans, peanuts, seeds |
| Threonine | Thr | Is an important constituent of collagen, Elastin, and enamel protein | Not applicable; it is best to consume whole proteins from animal sources to get sufficient threonine | Dairy, beef, poultry, eggs, beans, nuts, seeds |
| Tryptophan | Trp | A natural relaxant, helps alleviate insomnia by inducing normal sleep; reduces anxiety. | Not applicable; it is best to consume whole proteins from animal sources to get sufficient tryptophan. | Dairy, beef, poultry, barley, brown rice, fish, soybeans, peanuts |
| Valine* | Val | Alleviates muscle protein breakdown; used best in combination with Ile and Leu | 2.5 grams as part of a 10 gram serving of branched chain amino acids | Eggs, mushrooms, nuts, poultry, beef, soy, grain, dairy |
| Combine all of the Essential Amino Acids | Great for promoting muscle protein gain and alleviating protein breakdown | 6 gram dose taken pre or post-workout | Look for specialty supplements that contain the EAAs (e.g. BioBuilde). |
http://anrvitamins.com/glossary/
http://www.coachroblowe.com/nutrition-amino_acids-summary.htm
References
1. Antonio J, Sanders MS, Ehler LA, Uelmen J, Raether JB, Stout JR.
Effects of exercise training and amino-acid supplementation on body
composition and physical performance in untrained women. Nutrition.
2000;16:1043-6.
2. Tipton KD, Rasmussen BB, Miller SL, Wolf SE, Owens-Stovall SK, Petrini
BE, Wolfe RR. Timing of amino acid-carbohydrate ingestion alters anabolic
response of muscle to resistance exercise. Am J Physiol Endocrinol Metab.
2001;281:E197-206.
3. http://anrvitamins.com/glossary/
4. http://www.coachroblowe.com/nutrition-amino_acids-summary.htm