Let's talk about Proteins

PercivalHackworth

I'll continue on the nutrients presentation ; time for PROTEINS!
(Let's talk about Lipids is here :
http://www.myfitnesspal.com/topics/show/624586-let-s-talk-about-lipids )



Proteins are refereed as the «actives » molecules within the organism, due to the numerous functions they provide :
- Structural functions
-Information functions
- Signal functions
- Transport functions
- Defense functions
- Catalyze functions
and so on..

Proteins are made from amino-acids condensates. It exists actually 20 amino-acids –22 actually : the selenocysteine and pyrrolysine, but both depend on a specific codon (3 nucleotides sequence) :

- Alanine
- Arginine
- Asparagine
- Aspartic acid
- Cysteine
- Glutamic acid
- Glutamine
- Glycine
- Histidine
- Isoleucine
- Leucine
- Lysine
- Ornithine
- Phenylalanine
- Proline
- Selenocysteine
- Serine
- Taurine
- Threonine
- Tryptophan
- Tyrosine
- Valine

When the amino-acid chains have their molecule mass lower than 10 000 daltons, they are considered as “peptides”. For instance, glucagon and insulin are both peptides.

There are also amino-acids considered as free ones, since they are not incorporated to any existing proteins, for instance Ornithine and Citrulline are free amino-acids.

Main role of the amino-acids is the protein synthesis, but they can also provide energy, and participating in neoglucogenesis..
9 amino-acids must absolutely be brought by the diet in order to have your nitrogen balanced, and in order to ensure an optimal growth for the children. Those nine amino-acids are called “essential” ones :
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine (which themselves depend on cysteine intakes)
- Phenylalanine (which themselves depend on tyrosine intakes)
- Threonine
- Tryptophan
- Valine

For all other amino-acids, a synthesis is possible from glucose, thanks to the pyruvate (metabolite being found in several metabolic pathways), the oxaloacetate or the alpha-ketoglutarate.
(Note that it is impossible to synthesize an amino-acid from fatty-acids.)

Nitrogen balance, Protein needs and Essential amino-acids

Nitrogen balance is simply the azote intakes over azote losses. 90% of these losses occur via urines (with 80% as ureas) and around 10% via the faeces.
Some minor losses occur via the sweat the desquamation (tissues loss) or superficial body growths (hairs, nails)

The nitrogen balance represents the evolution of the organic proteic mass, assuming that last is not changing (free amino-acids and ureas) during the measuring period (usually from 3 to 5 days)
The result could be either neutral, positive (growth) or negative (loss being superior to intakes)

Neutral nitrogen balance
1100 to 1300 mg of high biological value proteins (eggs whites used as a reference) per lb permit a neutral nitrogen balance.

0,75g of high-quality proteins per kilo of body-weight should allow everybody to meet the requirements. (meat, dairies, milk, eggs, fishes) according to the WHO.

Essential amino-acids and required proportions
Here is the required proteic proportions per essential amino-acid :
- Histidine : 16 %o (16 per thousand)
- Isoleucine : 13 %o
- Leucine : 19 %o
- Lysine : 16 %o
- Methionine (+ cysteine) : 17 %o
- Phenylalanine (+ tyrosine) : 19 %o
- Threonine : 9 %o
- Tryptophan : 6 %o
- Valine 13 %o

Given the fact that most of us eat more than 100 g of pure proteins per day, it is easy to think most of the requirements are met, but it is possible to be deficient in some essential amino-acids, due to the quality of the consumed proteins and the specific needs on a given time.

Biological value of proteins
Biological value of a protein defines its digestibility, and its amino-acid profile. These led to the creation of a “limitation factor” notion (that the chemical index defines) and proteic usage (which integrate the digestibility coefficient and essential amino-acids proportion)

# Digestibility
The digestibility coefficient for a protein defines the percentage of azote being ingested over the non-digested amount, eliminated via faeces :

C = (N-intakes – N-faeces/ N-eaten) x 100

that coefficient depends on the nature of the protein, the amount of fibers, the cooking, etc..
Proteins from animals have a better coefficient than natural ones (95/98% for 75/95%)

# Chemical index and limiting factor
The limiting factor defines the inability for amino-acids to synthesize proteins due to insufficient intakes of one essential amino-acid. The synthesis is blocked when one or several essential amino-acid are lacking.

The chemical index is the percentage of an essential amino-acid for a given gram compared to the same quantity of that amino-acid in a gram of the egg albumin.
For instance 1g of albumin provides 70 mg of lysine, wheat flour provides 35 mg. The chemical index of the wheat flour is then 50 for lysine. In fact, when the chemical index is given, it is the most limiting amino-acid index which is given. Most limiting amino-acids are :
- Lysine
- Methionine
- Cysteine
- Tryptophan

When it comes to essential amino-acids, timing does matter .
You not only need to make sure the diet provide them, you also need to make sure they are all taken at the same time.

# Protein Efficiency Ratio
The PER is calculated by multiply the digestibility coefficient and the chemical index.
For instance the PER of meat is around 70%, while the egg albumin has a PER of 87%.
Mother's milk PER is around 95% - but of course, proportions need to be counted. For instance flour has a PER of 70%, but bread only contains 2,7 % of proteins, pulses around 25%, meat around 18%

# Animal and Natural proteins
Generally, proteins from natural sources have a lower biological value than animal proteins : their digestibility is lower and less essential amino-acids are provided (especially Lysine, Methionine, Cysteine and Triptophan).
It is nevertheless possibly to follow a vegetarian diet by combining proteins from sources with different limiting amino-acids : cereals (low in lysine), leguminous (low in Cysteine/ Tryptophan) or cerals with milk (low in methionine)

Essential amino-acid and defficiencies
Depise the 9 essential amino-acids I presented, some can turn to be essential – meaning the endogenous synthesis in no longer possible.
For instance, cysteine can be synthesized from methionine, but for the newborn or people suffering from hepatic insufficiency such synthesis cannot occur (same for thyrosine from phenylalanine)
During growth periods, arginine needs increase, while for alcoholics or for people suffering from hepatic insufficiency, arginine, ornithine or citrulline synthesis are insufficient.
During oxydating stress periods of inflammations, cysteine needs increase pretty much (cysteine provides sulphur).
Detoxification require glycine, for instance when it is an hepatic one

Presentation of some amino-acids
Some amino-acids play specific metabolic roles, but in regard to a diet, having them in quantity would likely unbalance the whole regimen, so it is useless to increase a food consumption for the amino-acids it provides

# Taurine
Mostly present into the muscles, blood plates and central nervous system. Taurine acts during the second phase of the hepatic detoxification (conversion of the toxins from solid to hydro-solubles compounds), for the calcium metabolism, for the central nervous system development, as an antioxidant, as as a component for glutamyl-taurine, a neuro-transmitter.
Taurine turns to an essential amino-acid when vitamin B6, cysteine and methionine are insufficient, and for the children.

# Arginine
Arginine is converted to nitric oxide and citrulline (NO) – NO plays a part in muscles relaxation (vasodilatation) – thus Arginine is currently studied again arterial hypertension.
NO also acts as a mediator within the nervous and immune systems.

# Leucine, Valine, Isoleucine
These three amino-acid are called “branched-chain amino acids” and directly promote protein synthesis. They play a major role into the muscular development, and represent around 33% of the amino-acid being used for muscular growth.
Into the mitochondrial cells, they can be totally oxidized but they can also be used for production energy.
They penetrate the main nervous system with a common transportation system used by tryptophan, tyrosine, phenylalanine and methionine

BCAAs, especially leucine are sometimes used for people suffering from anorexia or cancers. (High levels of tryptophan in the the central nervous system leads to a loss of appetite).
Since the transportation pathway is the same, some sort of “competition” appears with leucine and triptophane for the arrival within the central nervous system.

# Glutamine
Also known as “nitrogen shuttle”, glutamine and alanine play a role on the nitrogen transportation for more than half of the amino-acids.
Glutamine is mainly consumed by tissues which have a strong cellular development (such as lymphocytes and macrophages which use glutamine as fuel.

So that amino-acid could turn to an essential one (remember that some become essential when the endogenous production is not sufficient) when infections occurs for instance, or traumatic stresses (or even when the intestine are damaged)

# Proteoglycans
Proteoglycans are characterized by a polysaccharide chain which contain at least one amino-sugar. Proteoglycans play a part in ions transport, water rention (oh yes!) collagen synthesis and cell signals.
Glucosamine sulfate has been studied against arthirtis
(More reading here http://www.icnr.com/GlucosamineSulfate/GlucosamineSulfate.html )

# Proteic denutrition
The proteic denutrition can occurs in several cases, such as : bad absorption, proteic catabolism, deficiencies. Usually it's a slow and long process, but sometimes the denutrition of proteins could be as fast as f***. :

# Bad absorption
- Chronical pancreatitis
- Chirrosis
- Chronical diarrheas
- Leaky gut syndrome

# Catabolism
- Cancers
- Viruses (Mononucleosis)
- AIDS
- Diabete

# Catabolism with intakes deficiencies
- Anorexia
- Imbalanced diets
- Clinical operations


For an average Joe

around 150 lbs, we found :
~ 10 g of hepatic glycogen
~ 100 g of muscular glycogen
~ from 22 to 24 lbs of lipids
~ from 55 to 65 lbs of muscles (or more around)

… meaning an average of 12 lbs of pure protein – around 2 lbs of proteic nitrogen.
If proteins are removed from the diet during 10 days, a proteic denutrition could then occur , while in the appearances nothing changes. Such cases often occur : depression, anorexia, etc...

During a total fasting period, the protein deficit is around 250g per day, but the first lost proteins are not the muscular ones, rather most the “fast” compartments (liver, organs, digestive conduit and lymphoid organs which could lose around 50% of their proteins in 5 days).

At that stage, muscles are safe but auto-immune functions, hepatic work and even protein synthesis are way less efficient.

# Proteins and Carbs
It exists a strong relation between proteins and carbs intakes. If an average consumption of 150g of carbs is maintained, gluco-dependants organs needs are covered – if not, neoglucogenese is highly stimulated, leading to the production of glycogen from proteins breakdown ; meaning an increased catabolism.

Catabolism measures
Here are some tips to measure the catabolic rate :
- If a lose of more than 10% of the total weight quickly occurs (couple of days)
- Lee's formula : nitrogen loss = urines ureas (g/24h) x 0,56
- 3 methylhistidine passing through urines (almost all of the methylhistidine passing through urine has a muscular origin)
- Plasmatic albumin dosage from hepatic synthesis. Under 36 g/l, it is a moderated lose, under 30 g/l, a severe one.
- Plasmatic pre-albumin dosage : moderated around 200 mg/l, severe under 150 mg/l.


Here are my other posts in relation :
- Why eating proteins :
http://www.myfitnesspal.com/topics/show/526837-why-eating-proteins

- Protein powders :
http://www.myfitnesspal.com/topics/show/519718-protein-powders

000WhiteRose000

Thank you for the brilliant post!
I have a few questions:

1. I did not know that amino acids are synthesised from glucose! Interesting. Are some of them only synthesised from Glucose meaning that we MUST have Glucose in our diet to make them? Or are they primarily made out of proteins and only in their absence are they made from glucose?

2. What is Azote intake?

3. Is it important to obtain Neutral nitrogen balance? Does that mean that we consume enough protein but not too much?

4. What will actually happen if we do not consume all essential amino acids? What implication will that have or our health, training and body?

5. So BCAA increases appetite?

6. So if a lower amount than 150g carbs are consumed a day we lose muscle? How does that happen? I thought that while dieting it is important to up the protein intake to preserve muscle and combat muscle loss.

PercivalHackworth

Thank you for the brilliant post!
I have a few questions:

Thanks my friend, excellent :-)

1. I did not know that amino acids are synthesised from glucose! Interesting. Are some of them only synthesised from Glucose meaning that we MUST have Glucose in our diet to make them? Or are they primarily made out of proteins and only in their absence are they made from glucose?

Actually, this is the opposite that happens, amino-acids could be used for glucose production (the neoglucogenesis), they turn to glycolyse intermediaries, which leads to glucose.
This is when the intakes are not sufficient, or long period of fasting that such phenomenon occurs.
The neoglucogenesis from amino-acids though is the LAST process that occurs when synthesis from pyruvate, glycerol and lactate is not possible. (meaning when they lack).
You need at least to make sure to eat other nutrients not to have amino-acids used for glucose production

2. What is Azote intake?

Sorry, in french, Nitrogen is translated "Azote", my bad.
Proteins are the nitrogen source for the organism :-)

3. Is it important to obtain Neutral nitrogen balance? Does that mean that we consume enough protein but not too much?

It simply means a neutral nitrogen balance won't make the body able to synthesize more proteins : a neutral balance means you bring as much proteins than your body oxidates them.
A negative nitrogen balance means you degrades more protein than you bring in, a positive one meaning you bring more proteins than you oxidates.
In order for a muscle to grow, it needs to synthesize more proteins than it destroys, this only happens when the nitrogen balance is positive.

4. What will actually happen if we do not consume all essential amino acids? What implication will that have or our health, training and body?

If you don't have all essential amino-acids, you would on the long run suffer from defficiencies, and lack their functions. We saw each amino-acids plays a specific role in the body. Amino-acids conversion can occurs for some,
but when it comes to the essential ones, there is not any solution, since endogenous production won't happen.

5. So BCAA increases appetite?

Yes, but in fact, see it the other the other way : By having leucine, you cut down from lack of appetite since it prevents the triptophane arrival within the central nervous system.

6. So if a lower amount than 150g carbs are consumed a day we lose muscle? How does that happen? I thought that while dieting it is important to up the protein intake to preserve muscle and combat muscle loss.

Yes... and no...
We saw before using the amino-acids that constitude the muscles, you use first the amino-acids from several organs, but it assumes :
- intakes are not sufficient
- Long fasting

The body would start to synthesize glucose --> energy (ATP) from amino-acids if lactate, pyruvate and glycerol are lacking.
After that it would start to use amino-acids from organs for glucose, and when it depletes those compartments (which will lead to a decreased immune-system and weaknesses) that the body starts to use amino-acids from the muscles.
That is why it would take some time before losing muscles.
#1--- Body needs energy
#2--- It tries lactate/ pyruvate and glycerol
#3--- If it is not enough, it moves to energy production from amino-acids
#4--- It uses first the amino-acids from organs
#5---> You lower your immune system/ suffer from defficiencies
#6--- If it is not enough, it starts to breakdown proteins from the muscles
#7---> You lose muscles.

And this is exactly why we are eating proteins in the first place : not only you make sure to have a positive nitrogen balance ;
If your diet brings less carbs than your needs, the body would use the proteins in the very last resort, assuming storage are depleted and other metabolic pathways are not possible (energy production from fatty acids that occurs during aerobic phase for instance).
If you want to be safe, you could have an inverted ratio - the more you lower your carbs, the more you'd increase the protein intakes to make sure dietary proteins are being used for neoglucogeneis rather than amino-acids from organs or muscles

000WhiteRose000

Thanks! That clears things up.
Can you please explain the following, it's just me being a bit slow, I don't get it :-)

Yes, but in fact, see it the other the other way : By having leucine, you cut down from lack of appetite since it prevents the triptophane arrival within the central nervous system.

mmapags

Awesome as always Bro! Thanks so much!!

PercivalHackworth

Thanks! That clears things up.
Can you please explain the following, it's just me being a bit slow, I don't get it :-)

Yes, but in fact, see it the other the other way : By having leucine, you cut down from lack of appetite since it prevents the triptophane arrival within the central nervous system.

Well tryptophan is an appetite suppressant when it reaches the nervous system (but not only ! )
The pathway it uses is the same Leucine uses in order to reach the nervous system. By increasing leucine intakes, Leucine inhibits tryptophan metabolism and seem to compete for membrane transport.
You end up favoring leucine transport.
To be more precise, the tryptophan transportation rate is itself inversely proportional to the amount of others circulating neutral amino-acids (leucine, isoleucine, valine, tyrosine and phenylalanine) which compete for going through the hematoencephalic barrier (brain-blood barrier)

PercivalHackworth

auto-bump

anashar

Just read this - great info - thanks for sharing!

little_lisid

Thanks very interesting.

Unknown

This content has been removed.

MoreBean13

GREAT post! (and I don't give acclamations lightly!)

sarabluebell

wow that was so above my head....lol

amruden

Ya you broke it down for the Avg. Joe...
Now how about for the idiots, like me.

I don't care about the science behind it.

Protein is good.....right? Lol!!

Savemyshannon

GREAT POST!!! Thank you so much!

Sarauk2sf

Tagging to read when my brain is functioning better.

PercivalHackworth

Ya you broke it down for the Avg. Joe...
Now how about for the idiots, like me.

I don't care about the science behind it.

Protein is good.....right? Lol!!

A bit late, but yes, proteins are definitely good for us ^^

Dauntlessness

Thanks for sharing Mr. Smartypants