Thursday, September 2, 2010

Protein the Magnificent: not just about muscles.

Ask someone - particularly someone into working out - what protein is for - eating it; having it - and most of the time we'll hear "muscle building." And yes sure, skeletal muscle is the largest single source of protein in the body (50% of the lean mass of our bods is skeletal muscle) but that is just TOTALLY INCOMPLETE.

The Bigger Picture. Indeed, you may be as surprised as i was on first learning a more accurate answer to "what is protein for" is really "everything." - Just consider this list of what requires protein or just IS protein.
  • collagen, hair, skin, bone middles  - all big huge protein components
  • every cell in the body EVERY cell requires protein to be replenished or replaced
  • muscles for sure, but organs too:  protein protein protein.
  • the instructions for our dna, which inhabit cells, are proteins. The genetic code in the the ribosome (beside-ish the cell nucleus) for which all the recent research about "gene expression" comes, is protein.
  • hormones like insulin  - the messengers of what to do in terms of chemical processes to stop and start - are proteins
  • enzymes that are essential to metabolism and respond to hormone messages, yes, protein. Indeed there are 6 types of enzymatic reactions for moving, rearranging, breaking for reforming, joining, oxidizing. All proteins. Some are also faster others slower for limiting the rate of change. Amazing proteins.
  • antibodies for defending our cells against infection- more proteins. 
  • energy - yes, sometimes we need/use proteins to produce the ATP we need (usually refered to as "energy" ) to be able to move our muscles. 
Isn't that amazing? Are you amazed? I'm so amazed. But wait! There's more if we want to look at protein as macronutrient and how we get it out of food sources to join this functional dance - of which muscle building seems to be quite a ways down the stack of protein's things to do.
The Primacy of Protein
Like fat and carbs, protein has carbon and hydrogen. Unlike fats and carbs, protein has Nitrogen (part of their amino group). And here we get to the interesting bits. Just a reminder, nitrogen is fundamental to life (overview of nitrogen's role). This without nitrogen no life, and protein being in everything kinda hints at the reason perhaps for protein being called PROTEIN. As per this definition:

1844, from Fr. protéine, coined 1838 by Du. chemist Gerhard Johan Mulder (1802-1880), perhaps on suggestion of Berzelius, from Gk. proteios "the first quality," from protos "first." Originally a theoretical substance thought to be essential to life, the modern use is from Ger. Protein, borrowed in Eng. 1907.
Proteins are constructed things:
The smallest protein is an Amino Acid.  When little groups get together to make bigger groups we get Peptides, which form up as peptide chains

these in turn are bended and folded and twisted into various shapes that make it usable for whatever role these proteins have before they begin their new life as food.

What Happens to Protein in Digestion and Beyond?
What happens when we eat protein? First, most of the time we eat food that has protein in it, right as opposed to just "protein"? So, chew chew chew, masticate, get food into bits with saliva; then food into stomach.

Stomach As food hits the stomach, hydrocholoric acid gets dumped on it, which does interesting things to all food, but to protein it has the special process of denaturing the folded bendy structures of the proteins. While these structures are important for proteins to do what they do when in living cells, for use as food, these structures need to be, well, unpacked.

So, for the purposes of getting at the amino acids, denaturing starts hiving off the other bits of the protein structures that can be used for other things. (By the way, cooking and salting can also denature parts of proteins' stuctures in food).

So acid in the stomach is one part of the stomach process. But in the amazing life of proteins as doers of everything, other proteins-as-enzymes (pepsinogen into pepsin) get happening in the stomach to break the chains of amino acids that have been unpacked from the folds and bends. The remaining "polypeptides" and single amino acids head to the small intestine.

Small Intestine I dunno about you, but the way i've imagined the small intestine is just food getting pushed through a pipe. The stomach's a tank and the intestine's a pipe. Well, no. It turns out the small intestine is more like a conveyor belt where mechanisms operate at each stage on food that keeps processing and changing (metabolizing) the stuff that's in it.

If we're taking stuff apart, we're using enzymes (more proteins), and the small intestine is, in part, doing more disassembling. The pancreas kicks proenzymes into the small intestine, these get going with other enzymes that together act as the un-superglue of peptides.  Now we get smallers peptides and free amino acids heading for absorption.

Absorption and Over Crowding at the Border
Ok, i admit it, this next bit seems extremely cool to me and may even have practical implications for those of us who like to experiment with supplements. The small intestine has linings and stuff has to move through the linings to get to the blood stream. Before the proteins get into the next phase of processing (into the blood stream and most thence to the liver), they need to be transported. We won't go into it, but there are four types of transport processes, and each require energy - ATP (the stuff also used for things like muscle contraction) to do the job. So right there is an example of why just staying alive burns calories: moving amino acids out of the gut takes energy.

And by now, you guessed it, those transporters are also proteins. So here's the situation: there's proteins in the gut waiting to get moved to the blood supply. Peptides, branch chain amino acids, individual free form amino acids. They need transporters to take them there. There's a limited number of transporters at any one time and of any one type. We literally can get into a state of cuing up and overcrowding. Which peptides/amino acids go first? It ain't free form amino acids. Nope. It's the branch chain amino acids - these bigger groups take different transporters which seem to head out first.  Which is better than being caught in traffic. So next time someone talks about using bcaa's to get to their muscles fast after a hard workout, you know they're not kidding: bcaas it seem can get on the bus out of the gut quite effectively. The ones that get out, that is.

The Liver A lot of the absorbed amino acids (like glutamine) get used right there for energy and intestinal cell growth. If an amino acid makes it past being used for energy or local (non skeletal muscle ) cell building  (and only about a fifth of proteins ingested do), it heads into the blood stream into the amino acid pool.

Amino Acid Pool: Resources on Call for Just in Time Service.

The amino acid pool has about 100g of proteins ready and wating to be called into service at any time. That's not a lot but it's not a little. It's just getting turned over frequently as proteins are constantly being used and rebuilt.

Proteins are so important, and so versatile. Many can be constructed on the fly from available protein resources in the bloodstream, or the "amino acid pool." Part of the process of metabolism (changing stuff) is to take the proteins we ingest and convert them as needed by the demands of our bodies into the proteins we need. They can be converted into non-protein compounds (to be used in lieu of carbs in glyconeogenisis) and catabolized for ATP/energy conversion. Indeed, here's a shocker (to me): about 5% of the energy from longer duration activities comes from BCAAs.

This processing is where essential and non-essential proteins come into play. The essentials are the ones we need to ingest because we can't synthesize them.

It's a Wading Poo: No Deep End
That said, our bloodstream it seems is already pretty full with other stuff besides proteins cuing up for use. So we don't store a lot. Therefore, we need to ingest protein regularly. This need doesn't mean go nuts on protein. More doesn't always mean better, right? But it does mean that our bodies need a pretty consistent flow of them. And if it doesn't get those proteins from our diet? Our bodies will start taking proteins from other sources. Like muscle. And repurpose them. We're wired for survival not performance or prettiness.

Amino Acids: eat your veggies
This is just an aside to remind us that we can get the amino acids we need from plant based diets. And likewise if we rely on veggies, we will also be getting more than just protein. One of the advantages of a more plant based (i didn't say vegetarian) diet is that well, you get a lot of protein from eating a range of veggies, we also get lots of other nutrients not found just in meats/dairy, and they are less energy and calorically dense. So we can eat rather a lot, volume wise. If we get a good mix of veggies and legumes, we don't need to worry too much either about whether or not we're getting whole proteins and all the essential amino acids we need.

Protein turnover, though, means that likely the worst thing to compromise in one's diet IS protein
a) because we're mainly organisms made up of protein and water.
b) because we don't store a lot of protein for re-use in the amino acid pools and
c) because the proteins in all parts of us are constantly being replenished

Muscle is still Protein, right?
Muscle is just one of the tissues in our body that requires and turns over protein regularly. If all tissue cells have protein as a part of them, then presumably sufficient protein needs to be available for all the metabolic signalling (hormones and enzymes) and new tissue building (more amino acids), and sufficient energy stores need to be available to support the building process (ATP).

Protein synthesis is, as best i understand, cells' DNA signalling to say there's a need to create more protein of some kind for a particular requirement - whether that's a requirement to generate more hormones or muscle tissue or antibodies.  Muscle use - when pushed to adapt to new stresses causes existing protein to breakdown in normal turn over and to be rebuilt, and rebuild more tissue as needed. The tissue is largely protein based. But so are the cells in our body.

Protein turnover (catabolism and anabolism) is happening all the time in all parts of the body, not just muscle, as cells die, get flushed and replaced. In muscle building we usually focus on protein synthesis - the generation of new protein - and crave anabolism and fear catabolism. We want MORE not less. But protein turnover, it seems from all the above, is important, and part of staying healthy, and effects more or less everything in our bodies.

How much protein to eat?
I'm not going to get into how much protein do we need. The 1g to 1lb of body weight is a pretty grounded heuristic for two reasons:
  • it's very difficult to go toxic on protein (discussed here), so potentially overeating protein in the mix of other nutrients  is likely ok if one's going to err on a given macronutrient.
  • but, lets remember that overeating ANY food pushing into caloric surplus means what's not needed goes to fat.
For more, also checking out Brad Pilon of Eat Stop Eat on protein research (for muscle building) is a very interesting read.
    The point of this piece is less about hypertrophy - of which we know so little - and more to share or to raise awareness that muscle building for our body is just one job that protein has to support in the organisms that are us. For me, kinda puts muscle building in perspective and no wonder we know so little about it, since it's a part of such an integrated protein dance.

    News note: I understand b2d buddy Mike T Nelson is doing a chapter of a book on Protein with Lonnie Lowery (of a neat theory on the Pump, discussed here)  - so will look forward to that.

    In the meantime, i sing the body electric may well be replaced with i sing the protein electric, from the smallest signal to cell to the building of that cell, protein is involved. How 'bout that?

    Beyond the links in this post, the Essentials of Sport and Exercise Nurtition (certification manual) by Berardi and Andrews along with  Exercise Physiology and Advanced Nutritionhelped inform this presentation. Any errors in presentation are mine.

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    1 comment:

    Mike T Nelson said...

    Good overview MC. Thanks for the shout out.

    The book on "Protein and Athletes" should be out some time in 2011 and tons of the top protein researchers are in it, which is awesome! Yep, I am in there too on a chapter with Jonathon Mike about practical cases studies based on the literature in regards to protein (weight loss, overtraining, etc).

    YES--I do think that tissue turnover is very very key.

    Eating more protein allows the body to break down more protein, but also build up more protein (muscle and other tissue) for better body composition (more muscle, less fat).

    This fits in with the theory of Metabolic Flexibility too.

    Rock on
    Mike T Nelson PhD(c)
    Extreme Human Performance


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