This week, we're going to discuss the 
macronutrient protein. 
When we think about proteins, we can 
construe those to be the building blocks 
of human anatomy. 
They serve many functions and are crucial 
for growth, development, and maintenance 
of the human being. 
When we think about this analogy that we 
are what we eat, proteins that we eat, 
like lipids, become proteins in our body. 
I've also made an analogy to the idea 
that human beings, the body is somewhat 
like a factory. 
We can think about this human factory 
producing various products and needing 
other products to run, to run efficiently 
and to manufacture what it needs to 
manufacture. 
When you think about calories, proteins 
do have calories, calories are fuel. 
Now remember, carbohydrates are the 
preferred fuel source for our bodies. 
They are what stoke the fire of the 
factory. 
Lipids help run the show. 
They make sure everything is running 
properly, keep things lubricated. 
They make sure that products are 
delivered to the right locations. 
They help us synthesize hormones that we 
need to regulate This mechanism its 
factoring. 
Proteins not only build the factory, but 
they're also very important for the 
running, and the regulating of the human 
body. 
So, we consider these proteins as the 
building blocks of the human body, we 
really need to discuss amino acids. 
So truly, if the amino acids that are the 
blocks of all proteins creating proteins 
whether they are, you know, plants, 
animal or in our own body and tissues. 
Let's take a look at amino acids. 
Amino acids have similar chemical 
construct, one difference is the side 
group. 
This is what will really identify a 
protein, it's what makes a protein one 
amino acid. 
Different from another. 
They all have this central carbon. 
The amino and acid group has amino acid 
and a hydrogen. 
Various amino acids are either essential 
or non-essential, depending on that side 
group. 
There are amino acids such as aspartate. 
So compare that to, for example, alanine. 
Phenyalanine, so you can see that these 
are groups, this side group can be simple 
or complex. 
Here we see one with a ring structure to 
it. 
To it. 
Glycine, very simple, just a hydrogen, so 
you can read in your text book what 
specifically which amino acids 
specifically are essential versus others, 
but to just give a better understanding 
of what this means simply is we can not 
synthesise, The non-essential amino 
acids. 
Something about their chemical structure 
that are a group while we are not 
synthesizing that amino acid. 
Non-essential amino acids can be 
synthesized. 
Now, we do need essential-amino acids in 
order to do so but we can actually 
manufacture certain amino acids in the 
body. 
In this process, we actually break down 
the components of another amino acid to 
make a new amino acid. 
So if we take amino acid A off at the top 
left, 
we convert that to amino acid B, down at 
the bottom right. 
We're simultaneously converting a-keto 
acid, keto acid b to keto acid a. 
So look at the chemical structure of a, 
look at the difference in amino versus 
the keto. 
What's changed? We see that NH2 group. 
That amino group is what's changing from 
a keto acid to amino acid. 
Makes sense. 
So amino acids make protein. 
Proteins are one of those complex 
macro-nutrients structurally. 
We have a specific sequence of amino 
acids that will come together, then fold 
in another specific sequence, and then 
different proteins can actually. 
Work together to create a complex 
protein. 
Example of this is haemoglobin. 
Now, haemoglobin is a complex structure 
made of four sub units of protein and you 
can look that up in your text book as 
well, little bit about protein structure. 
So I'd like you to understand at this 
level, is that when we look at a protein 
whether it be in a food or in a body, the 
breakdown of that protein or the 
denaturazation of that protein does 
change its structure and its function. 
When we denature a protein it's not going 
to have the same function. 
Function for protein is dictated by 
structure. 
Amino acid sequence, folding all these 
levels of structure affect how p how 
protein work. 
You can actually see a very easy example 
of how this is when you go cook a meal 
leaving breakfast. 
Eggs are a great example, not only are 
they actually the ideal protein when it 
comes to the contents of amino acids in 
them, we'll talk about that in a moment, 
but eggs, when cooked, change their form. 
So we can have a raw egg. 
That certainly looks one way or 
hard-boiled egg, 
certainly very different structurally, 
texture-wise, consistency. 
Different from a scrambled egg or poached 
egg, different from a quiche or an omelet 
and different from a whipped egg. 
Any two of these processes. 
Process is whether we boil an egg, 
scramble it, fry it or whip it, we are 
denaturing the protein. 
In. 
the digestion lecture. 
you actually learned how proteins are 
broken down. 
and thus. 
in the human body denatured. 
The structure and function that the 
protein had in your food, whether it be, 
in the egg, or amino acids in a plant, or 
amino acids in chicken They serve some 
function in the chicken and the planter 
and the egg. 
They could potentially serve very 
different function in your body once 
those amino acids are taken apart, put 
back together, into a new protein. 
The other important factor nutritionally 
when we talk about proteins is protein 
digestibility. 
When it comes to protein digestibility 
the type of protein is going to be 
important. 
Not just whether it be proteins or amino 
acid that came from meat versus plants, 
but different meats have different levels 
of digestibility. 
Protein digestibility is not just 
important when it comes to breaking down, 
obtaining the nutrition and amino acids 
we need from the meat itself, or the food 
itself. 
But also all the nutrients that are 
compounded in that protein matrix. 
Later we'll talk a little bit about 
vitamins and minerals. 
One vitamin that is very affected by 
protein digestibility is B12. 
As we get older our ability to digest 
food decreases. 
This includes proteins. 
So you might have two meal options to get 
B12 and protein, of course, perhaps a 
steak or chicken. 
Now though the chicken has less vitamin 
B12 in it, compared to the beef, the 
chicken's vitamin B12 is more digestible, 
because the chicken itself is more 
digestible than beef. 
When macro-nutrients bind micro-nutrients 
so when a protein finds certain minerals 
or vitamins. 
If we can't digest the protein, we can't 
create a vitamin and will not absorb or 
utilize that vitamin. 
So we talk a little bit about protein 
nutrition. 
When you read about protein nutrition you 
think about protein sources and what 
other vitamins they might supply or 
minerals they might supply. 
Keep in mind that the mineral or vitamin 
content of any given protein is only as 
good as its digestibility. 
This also, of course, is going to apply 
to amino acids, so when we think about 
how good a protein might be or protein 
quality. 
So when we think nutritionally about 
protein, digestibility is going to be 
very important, not only when it come to 
bringing amino acids, and gaining these 
essential or nonessential amino acids in 
our diet, but also green based vitamins, 
such as B12 as the example I gave. 
So now, we think about amino acid 
content, and digestibility, we can talk 
about protein quality. 
Now in the simplest terms, protein 
quality is simply about the essential 
amino acid content. A complete protein 
will have the perfect ratio of amino 
acids needed for human growth, 
development and maintenance. 
Incomplete proteins are the one that one 
or more special amino acids and these are 
typically plant proteins. 
Animal based proteins are typically 
complete. 
Whatever amino acid is present in lowest 
amounts will be considered the limiting 
amino acids. 
They will limit the protein's capacity to 
synthesize body protein. 
Now, if you live in a situation where you 
only have one food stuff, and it is plant 
based, you might see imbalances in amino 
acid availability and protein synthesis. 
But if you have some variation to your 
diet, even if you have access to just 
rice and beans, you will get all the 
amino acids that you need. 
If you're a vegetarian you may have heard 
of terms such as complementary protein, 
combining foods to get all the amino 
acid. 
And while getting all the amino acids is 
very important It's not a matter of 
getting it in the same meal. 
If you get all of the amino acids that 
you need on a regular basis, even if it's 
a daily basis, you can say something as 
specific as a daily basis, you will have 
the proteins, you will have the amino 
acids that you need to synthesize 
protein. 
So we have the egg as our example 
protein. 
These are the, this is the amino acid 
content of an egg. 
The essential amino acid content. 
And we can compare this ratio to other 
proteins to determine its quality. 
There are now different analytical and 
laboratory methods for determining 
protein quality. 
We can consider the chemical score. 
This is the most basic analysis. 
This will compare the essential amino 
acid content of any given protein, so 
perhaps some chicken, to the numerical 
score generated from the ratio found in 
an egg. 
Now chemical score does not consider 
digestability. 
We can also measure protein quality 
through biological value. 
Biological value's determined by nitrogen 
retention in animals that attest protein. 
A biological value over 70% supports 
human growth. 
We can also measure protein quality by 
protein efficiency ratio. 
This measures weight gain in animals fed 
a test protein, and it is the measure 
used for protein comparisons of infant 
formulas and baby foods. 
Finally we have the protein digestiblity 
corrected amino acid score. 
This measures essential amino acid 
composition. 
Compared to needs, with an adjustment, 
for digestibility. 
This measure, is what is used, to 
determine, percent daily value. 
That's the number you see on all your 
food labels. 
This, we are going to explore, some more 
in a few moments. 
Alright. 
So let's first look at amino acid's 
score. 
On the left you can see a list of 
essential amino acids, followed by a 
column with our reference protein and our 
test protein, which is beans. 
These amino acids are given in milligrams 
of amino acids, program protein So in 
this case what's our limiting amino 
acids. 
As we go down the list we say most of 
these amino acids actually scored over 
one. 
Our limiting amino acid is lysine. 
It's less than one so therefore it would 
be the missing essential amino acid in 
this food. 
Food. 
We can compare different scores of 
different foods, so again, this is our 
Protein Digestibility Corrected Amino 
Acid Score. 
Casein, eggs, and other animal based 
foods are going to have a score of 1. 
Soy beans actually that make tofu and 
tempe are very high for plants, .99, it's 
almost 1. 
Beef is lower, so why is that? Well, 
there is an adjustment for digestibility. 
Beef, as I mentioned a little earlier, 
has a lower digestibility than other 
meat. 
So even though it is a complete protein, 
so if we looked at potentially its 
chemical score, it would get a high 
chemical score. 
The digestibility in beef lowers its 
digestibility corrected score. 
As you look further down, you see the 
numbers drop. 
Whole wheat bread, for example, has the 
lowest Protein score. 
So let's see how this, these numbers 
actually add up. 
So with the beef equation there you might 
have expected beef to have a higher 
score. 
Let's consider peanuts. 
There's the equation for the actual 
score. 
We can see that the amino acid score that 
I mentioned earlier, that's actually 
comparing our test protein, peanuts. 
To an example protein, the egg. 
We'll then multiply that by its 
digestibility. 
We take the amino acid score from the 
profiled amino acids by measuring the 
lowest amino acid available. 
So the score is going to be coming from 
the lowest amino acid. 
In the case of peanuts the lowest amino 
acid score .49. 
So 94% digestible so we'll multiply this 
times .94. 
Then our final score is .46. 
This is not 100% digestible. 
We've lowered the score relative to its 
lowest amino acid. 
So how do we compare this to the daily 
value if I buy a bag of peanuts and I 
look at the label? How do I know where 
this daily value came from? Well now we 
can see percent daily value by knowing 
our own given daily value, the 
established recommendation, and comparing 
that to... 
The score so now we can divide the score, 
that final score that we get, times the 
amount of protein per serving. 
Again when we look at daily values of a 
food label they're given in servings. 
And divide by the daily value, again 
amount of protein times the score, 
divided by the daily value. 
So, let's say we had 7 grams of protein 
in our sample of peanuts. 
The score was 0.46, and the daily value 
is 50 grams protein. 
So, this amount of peanuts provides us 
with 6.4% of our daily value. 
Of protein. 
Considering the amount of protein in the 
food and its amino acid content and 
digestibility. 
Alright now lets compare peanuts to 
another protein, something that is very 
digestible and has a solid amino acid 
profile. 
Yoghurt is a great example. 
It's a healthy food and it is a complete 
protein. 
It scores one. 
Highly digestible, gets us all the amino 
acids we need. 
It provides, in a serving, 10% of our 
daily value of protein. 
Now if we look at the amount of protein 
per Food, 5 g of protein in yoghurt 
versus 7 g of protein in peanuts, we 
think hm, peanuts will give me more 
protein. 
I need protein, 
I should eat peanuts instead. 
But when you consider digestibility and 
the amino acid profile, you see that 
peanuts actually provide less amino 
acids, less of a daily value of proteins 
than yoghurt. 
Certainly, you can have some peanuts with 
your yogurt, but if you're going to 
choose one over the other, the yogurt is 
the more complete protein providing more 
amino acids, especially essential amino 
acids, when we're choosing between one or 
the other. 
So I alluded to before the concept of 
vegetarianism, and combining foods to 
have complimentary protein. 
So regardless of where your beef is, in 
the field or on your plate, you can eat 
healthy. 
There's certainly numerous healthy 
benefits to becoming a Vegetarian, or to 
simply eating a higher plant-based diet. 
Plants, fruits and vegetables, are higher 
in fiber. 
They come with a significant amount of 
essential vitamins and minerals. 
They're lower in fats particularly 
saturated fat. 
And while meat can be a very good part of 
a balanced diet it does not have to be. 
And again reminding you, too, that this 
idea of complimentary proteins, while 
certainly it is important that you eat a 
very Level of protein in your diet, you 
eat different fruits, nuts, and seeds, 
beans, legumes, vegetables, whole grains. 
It doesn't mean that you have to eat 
every single one of these, at every 
single meal, to get the amino acid that 
you need. 
When it comes to proteins and amino 
acids, it's the amino acids full in your 
body that's important not just the 
stomach content. 
This amino acid pool is where we get, 
what we need to make proteins. 
Body proteins, new amino acids. 
To even generate glucose, glycogen and 
lipids, we'll talk more about that in the 
metabolism section. 
To make non-protein compounds that do 
require amino acids or nitrogen. 
And then, of course, some of the amino 
acids from the amino acid pool will be 
broken down and excreted. 
This pool When kept constant will always 
supply the body with amino acids it 
needs. 
So again, as long as you eat what you 
need to during the day, it will supply 
the amino acid pool and you will be able 
to make the proteins you need. 
Now, individuals really interested in 
protein generation. 
Body builders, for example, that want to 
build large amounts of muscle mass. 
Or individuals recovering from 
significant illness or a burn may want to 
make sure that they're constantly 
refreshing this amino acid pool through 
the diet. 
Why is that? Well if you need to draw 
more and more out, look at the way these 
arrows go. 
You are going to get amino acids from the 
breakdown of body proteins if necessary. 
So, if you're trying to minimize body 
protein utilizations, you make amino 
acids for this amino acid pool, or to 
break them down, eating more protein will 
be protective. 
So, if you are a weight lifter, or 
someone in hospital or you're treating 
someone in a hospital that has a 
significant amount of tissue loss, making 
sure they get proteins through out the 
day And really the amino acids you are 
looking for them to get, making sure they 
get these amino acids throughout the day 
to keep, and you can even see some 
individuals in the extreme of this that 
will eat every two hours even during the 
night to make sure they are constantly 
bringing in new fresh Amino acid. 
Now if we simplify this concept of amino 
acid pool. 
We can break it down all the way to the 
nitrogen that's in the amino acid. 
Nitrogen is what sets amino acids and 
proteins apart from the other Core 
nutrients. 
Carbs and fat don't have nitrogen. 
When we look at protein balance, and when 
I consider the protein status of an 
individual, we can actually talk about 
nitrogen balance. 
And you can read a little more about this 
in your text. 
But to just give you a basic idea of 
what's happening, when we look at stasis, 
or the even state, we'll be in nitrogen 
balance. 
If we're eating more protein than we're 
excreting, we'll be in positive balance. 
If we're excreting more protein, than 
we'e taking in, we'll be in negative 
balance . 
So a healthy adult, for example not 
growing any more, they'll be in 
equilibrium. 
They'll be in balance. 
Someone who is growing is going to be in 
positive nitrogen balance. 
In pregnancy, you're in positive nitrogen 
balance, as well as when recovering from 
illness, particularly in a burn type 
situation, or any illness where 
significant tissue damage has occurred, 
and significant tissue synthesis must 
happen to you. 
Negative nitrogen balance is when we're 
losing more nitrogen. 
So before we get to the recovery stages 
of an illness, for example, we may be in 
negative nitrogen balance. 
So that burn victim in this early stages 
of synthesis is going to still be losing 
more dead tissue. 
That dead tissue's. 
It's going to break down. 
We're going to break down the amino acids 
in that tissue, the nitrogen in that 
tissue. 
And continue to lose more nitrogen than 
we are taking in. 
So, in certain situations we do want to 
make sure we're eating more protein so 
that we're supplying more nitrogen to 
help the healing of. 
Occur. 
So you will see, a dietician, for 
example, considering protein more, in 
certain individuals, that do need more 
nitrogen to heal. 
Alright, so we know a little about 
proteins, in the diet. 
What proteins are doing, how the amino 
acids are important. 
But what, do proteins do? Okay, they 
build body tissues. 
Hair, nails, skin, those are all 
proteins. 
But proteins do other things, than just 
making body protein. 
They're very important for all of our 
tissues, bones, teeth, collagen, muscle 
fibers. 
But they're also important on their own 
not just part of a muscle matrix as 
transporters. 
Our proteins are our transporters. 
We talked in lipids about the cell 
membrane and the importance of lipids for 
a healthy cell membrane. 
Well proteins are also very important 
there. 
They'll actually be the pumps. 
They'll be the vessels, the streets, if 
you will, the pathways from one side of 
the cell to the other. 
We can see various types, of, proteins. 
Pushing, components from one cell, side 
of the cell to the other. 
What's most important here is it's the 
protein that are these transporters. 
Insulin for example, the insulin receptor 
and the insulin transporters are protein. 
So taking that example, the protein 
function in diabetes or in blood sugar 
control, so the pancreas is going to 
generate the insulin in response to blood 
sugar going up after we eat a 
carbohydrate. 
And insulin is actually going to signal 
transporters to go to the cell wall, 
become available to pick up glucose and 
draw the glucose into the cell. 
Once in the cell, blood sugar lowers. 
Without protein and protein 
insufficiency, we can't continue to 
generate those transporters in cells and 
we can impair this process. 
So protein deficiencies affect our 
transportation, which can effect delivery 
of numerous things from one place in the 
body to another. 
Proteins are also very important in 
maintaining water in right locations. 
We'll talk a little bit more about that 
when we talk about electrolytes. 
But along with electroytes, protiens are 
very important with attracting water Into 
the cardiovascular system and keeping 
water where it should be, in the veins an 
arteries. 
Someone that does have protein 
insufficiency may develop edema. 
Edema is simply when water that's meant 
to be in the vessels leaks out of these 
vessels and enters the body tissues and 
we see swelling. 
And the swelling, specificically edema is 
due to low protein, not keeping water, in 
the vac, cardiovascular system allowing 
it to build up in those tissues and 
swell. 
Proteins are also very important buffers. 
They can actually donate or accept 
electrons to help maintain that acid base 
balance. 
The lower the number the more acidic. 
The higher the number the more basic it 
is. 
And so proteins along, and again we'll 
talk about, with electrolytes are very 
important, buffers. 
Protein is also important in glucose 
production and energy production. 
Certain amino-acids, termed glucogenic 
amino-acids, are converted to pyruvate 
when broken down, heated and can then be 
converted to glucose. 
We'll talk a little bit more about this 
we get to metabolism. 
Other amino acids, termed [UNKNOWN] are 
converted to Acetyl CoA when broken down, 
and so they are not going to be able to 
be utilized in generating Glucose. 
Protein deficiency is a significant 
problems across the globe. 
Certainly, here, in the modern world, we 
have both protein excess, calorie excess, 
malnutrition of all kind. 
But protein deficiency has long been a 
concern for global assistance groups. 
Encroaching defficiency, we can see the 
classical images of a child looking 
emaciated still somehow have that swollen 
belly and feet, swollen arms, swollen 
hands. 
This is a [UNKNOWN] So remember we said 
that proteins are very important at 
keeping water where it belongs in the 
cardiovascular system. 
When we don't have enough protein this 
water leaks out. 
When we don't have enough calories, child 
will not thrive. 
So here we see example, of not just 
failure to thrive, but protein and 
calorie insufficiency. 
If we are getting enough protein, and 
we're just not getting enough calories, 
we won't see any edema in that child. 
That's a little bit about protein, so 
don't forget you should be reading these 
chapters before you listen to my 
lectures, so these lectures should 
certainly be building on what you've read 
and help tie things together.