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OK, so now we're going to turn our attention to proteins
and we're gonna start with a conversation about amino acids.
In our presentation today we're going
to cover different forms of amino acids,
their basic structure, and how they make up proteins.
We're also going to look at this process called denaturation,
or denaturing of proteins.
And, just like our treatment of digestion with carbohydrates
and with lipids, just the basics.
We're going to spend some time looking
at the role and function of proteins in the body
and why it's important for health
that people have proteins, different protein requirements,
depending on people's age or their life stage,
for instance during pregnancy we need more protein.
Also protein requirements, just a little bit
around physical activity.
Then we're going to look at what happens
when we have too much protein, as well as too little.
So we want to start with a conversation about amino acids.
And if you think back to high school
you might remember that amino acids
are the building blocks of proteins.
And that's absolutely true.
So I want to show you what a basic amino acid looks like.
So if we come over and look at this picture,
I'll just invite you to appreciate
that this is the form of an amino acid
and you see certain components.
So we have something called an amine group,
and this is where it gets the name amino acid.
And we have a structural backbone,
just like we saw a backbone in triglycerides.
We saw that glycerol backbone.
We have a similar structure here with an amino acid.
And then we have an acid group and a side chain.
And this side chain right here is really
the variable with amino acids.
And we'll talk about these different amino acids that
are required in human nutrition.
We have nine essential amino acids.
And each one of them is distinct and it's this side chain
right here that really is going to talk about structure,
and when you look at structure in biology
it dictates function.
So I'm not going to expect you to draw an amino acid.
That's not necessarily important.
But we want to understand a little bit
about its molecular makeup, and then
spend some time looking at the biology of proteins.
So when we have that amino acid structure
we're going to see that they connect together.
So you have a whole bunch of amino acids strung together,
and very often I like to think about these different molecules
in nutrition as pearls or little beads.
So you can see here we have a nice string
of different amino acids, and they're all
in this nice kind of linear formation.
Each one of these you can think of as a bead or a pearl,
and they come together as this nice, elegant necklace.
And it doesn't matter, for our purposes,
what order they're in.
Of course, in biology that's a critical function
or a critical importance for amino acid, what order they're
in, especially when we start to look at genetics and things
like this.
Because slight variations in the arrangement of those
amino acids is going to dictate different kinds of activities
in our body and things like that.
So now within each one of those amino acids,
they're hooked together.
And you'll have two of them together,
and that's a dipeptide, we call it.
What holds those together is something
called a peptide bond.
So again, if I come back over and look at this nice pearl
necklace, right here we have a peptide bond.
And here's another one.
Now it gets a little bit confusing sometimes to people
because we talk about this as the peptide bond.
But we can look at these two pearls or these two amino acids
as a peptide.
So a dipeptide or three of them would be a tripeptide.
And we can go on with this, and talk
about peptides of different lengths.
And again this becomes important when
we start to look at digestion, and we're breaking down
these long strings of amino acids
into their individual components.
So from that long pearl necklace,
we see an opportunity for much more sophistication
with amino acids.
So you can look at this particular strand here.
And this one is very curved, you can kind of
get that impression.
And if you think about something like DNA,
that double helix that we're familiar with from Watson
and Crick.
What has happened there is that amino acid strand has undergone
a conformational change, so it has
folded into its mature protein form.
And we can see another one here, where you have these big loops
and turns and twists and things like this.
The way that a protein folds, or its shape when it's mature,
or it's reached this final stage of development really,
this particular form is a nod to that side chain.
So if you were to have a really big side chain on one
of the amino acids, like a proline group,
that's a really big one.
So it's going to dictate that the protein fold a certain way.
And that's really not important for nutrition that much.
Again, it's more about biology, in a strict sense,
and genetics and things like that.
So I mentioned that we have some essential amino acids.
And I really want you to recall that term
essential in nutrition means that we
have to get it from the diet.
We can make a lot of different amino acids in our body.
But there are nine that we can't make.
So these have to come from the diet.
We also have some that are considered conditionally
essential amino acids.
And under normal circumstances these wouldn't be essential
but for different reasons related to diet, generally
speaking, or maybe there's an inborn error of metabolism,
they become conditionally essential.
So that would add another one of the amino acids to our nine
that are essential.
So now that we understand the whole structure
of an amino acid and how it makes up a protein,
we want to spend some time looking at taking these apart.
And this process of dismantling proteins
is a process called denaturation.
And this is an irreversible shift in protein shape.
So if you think about an egg white.
There are a lot of things that we can do to an egg white,
but no matter what we do we can never get it back
to an egg white, back to that form when
it was un-messed around with.
So there are different ways we can do this.
So we can certainly do it through heat.
I could crack an egg and put it in the pan and the egg
white turns opaque and becomes very solid.
But again, I can't un-ring that bell.
I can't take it back to its unheated form.
And you can do this also with acids.
Maybe you can think about something like ceviche,
if you've ever had that.
So it's a raw fish or a seafood that's
been poached in a different kind of an acid, generally
a lime juice or lemon juice or something like that,
and it denatures the proteins in there.
So it turns that fish from being very
translucent to being opaque.
You can also do this with bases.
This is a little less common in culinary traditions.
You could do this with alcohol as well.
So if you were to marinate a steak in beer or something
like this, you'll notice that what happens
is that the meat becomes much more tender.
And this is really this breakdown
of some of those fibers in the meat, the different kinds
of protein fibers.
And you can do it with heavy metals.
And again, you wouldn't do that in your home kitchen.
Silver nitrate is a good example,
where we would use a heavy metal.
So this is really important for the digestion of foods,
and if you're thinking ahead, maybe you've
got an inkling of how this happens in the human body.
And we use one of these processes, acids.
So hydrochloric acid in the stomach
does this process for us.
Now, we kind of understand the whole goal
of denaturing proteins to some extent.
We're taking a long protein chain
and we're going to break it down into amino acids.
And from there it's very easy for us
to absorb them in our small intestines,
and those amino acids can go all over the body
and do the job that they're supposed to.
So we're gonna start in the mouth, of course.
That's where really the whole process begins.
And there's not really a whole lot of digestion,
of course, that takes place in the mouth.
But the proteins are chewed and they're
starting to be mixed with saliva,
and they're dismantled a little bit.
So it's a chemical process.
And, of course, I can do this in a lab as well.
So if I were to put a piece of tissue in a blender
and puree it, it's very easy for me
to extract different kinds of proteins from it.
There really is not a significant change
in the protein structure in the mouth.
It's just more that we're starting
to break down that large piece of protein into smaller pieces.
And then in the stomach, this is where that hydrochloric acid
comes in.
I mentioned the acid is how humans
are going to denature proteins.
So there are particular cells in the lining of the stomach that
are responsible for this.
They're called parietal cells, and their job
is to make the hydrochloric acid.
Now sometimes people have different issues
with too much acid production and occasionally too little
acid production, especially if they're
taking acid reducers or different kinds of medications
that are going to reduce the amount of acid that's produced.
And you might again be thinking ahead
and say, well, what happens with that lining of the stomach
if I'm producing acid?
How come the stomach doesn't get denatured?
How come I'm not harming these different delicate structures
in the stomach?
And has to do with a layer of mucus.
So within your stomach, in this like circle or bag,
you can imagine, you have this nice ring of mucus.
And its job is to protect the stomach lining.
So from the stomach, that undigested food
is going to move into the small intestines.
And this is the site of major digestion
and all the breakdown of food, just
like we saw with carbohydrates and with lipids.
Here we're going to have protease enzymes doing
the activity.
So again that a-s-e ending should let
you know that it's an enzyme.
And what you see here is these long strings of amino acids
are getting broken down into peptides
or even a dipeptide form.
So we have one here that's two individual amino acids,
and they're held together with the peptide bond.
And here we have a tripeptide.
So you're going to see a lot of these small fragments
in the small intestines.
And that really just means that those protease enzymes
are doing their work.
And just if you want a little bit more nomenclature,
on this slide I also have a new word for you, oligopeptide.
And so this is a term you might be
familiar with from the carbohydrates chapter,
meaning that we have between four and 10
of these amino acids strung together.
All right, so now we want to look a little bit more
closely at what's happening.
So we have a little cross section
of the small intestines.
And if we blow this up and look at it,
you can see here we have these nice pearl necklaces,
or a whole bunch of beads strung together.
Those are our individual amino acids.
And as they're being broken down by the protease enzymes,
you get these little couplets and triplets
of the amino acids.
Now these are small enough that they're
going to move very, very easily through the epithelial membrane
of the small intestines.
And you see that happening here.
One thing I just want to mention is
you have those protease enzymes in the lumen
of the small intestines, but you also have it here
on this surface membrane of the epithelial layer.
So these different products of digestion
are going to move through those cells and right
into the bloodstream.
It's very, very easy, then, for your body
to transport those individual amino acids around the body
to the different cells that can use them.
So it's a really very simple digestive process.
There's not a whole lot we have to worry about there.
We aren't seeing any protein carriers necessary,
like we did with the different chains of large lipids.
All right, so from the digestive process we have to think about,
well how is that protein going to be used in the body?
So we want to look at the role of amino acids and proteins
in the body and the different places
where we're going to see them playing a critical role.
So I want to just point out a few areas in particular.
There are of course many, many more areas
where protein is used but especially when
we look at a growing embryo or a fetus.
Protein needs during pregnancy are about twice as much
as a non pregnant female, so she needs about 25 grams more
protein because she's growing all the structures of pregnancy
and fetal development.
Also an athlete in training, someone
that is purposely trying to build muscle
or is just getting stronger through physical activity.
A growing child, somebody who's maybe given blood and they're
replacing blood, or they've had surgery.
Of course those are going to be important areas where
we need additional protein.
And then for new hair and nails.
And sometimes with people who are coming
into a clinical setting, one of the signs we would look at
is the quality of their hair and their fingernails,
and sometimes that can be an indicator of health.
It doesn't always dictate that there's a protein issue.
It can be many other things.
But again it's sometimes a good sign to look at.
We see also protein has this maintenance role.
So we're not only building new structures
and expanding structures and strengthening them,
but we're replacing worn out cells.
And red blood cells are a really good example of that.
They tend to live about 90 to 120 days,
so it's a very predictable schedule of replacing these.
We also see intestinal cells.
So if you think about all of those cells that
line the 30 feet of intestines, they have this critical job
and they're exposed to all kinds of waste products, carcinogens,
and things your body doesn't want.
So they do not live very long, three days or so.
And it's good that we have that turnover because it really
reduces our risk of cancer.
Because if cells become damaged, that's
why we can see them growing in inappropriate ways.
And also skin cells.
And this is something we see all the time,
this constant replacement.
So a few other areas where we may not
be as familiar with the role of proteins.
Enzymes, if you remember, enzymes are a protein molecule.
And that is going to be important,
so keep in mind when we start to talk
about people that have too little protein.
Also antibodies, cellular transport,
moving things in and out of cells.
Hormones are proteins as well.
And then we also see some cellular activities,
we call them cellular pumps.
So a lot of people are familiar with the sodium potassium pump,
and that's a protein molecule.
Also, oxygen carriers.
And maybe you're familiar with hemoglobin on red blood cells.
The job of that hemoglobin is to be able to bind oxygen
and carry it throughout the body.
And so when people don't have enough protein their ability
to carry oxygen can be compromised.
Then structurally in our body there
are a tremendous number of roles for protein.
And probably a lot of these are very familiar to you.
So structural things like tendons and ligaments.
Also scar tissue, that's protein as well.
Fibers of muscles, and so on.
Bones and teeth, and you might not really
think about bones as being high reservoirs of protein,
we think of them as minerals, but you also
have to have protein there.
Hair and nails as well.
So now we want to spend a little bit of time just thinking
about digestion.
This is a question I often get.
People want to know which protein
foods are most easily digested by your body.
And sometimes this surprises folks.
So we see that animal proteins, especially things like meat,
are very easily digested.
And they have a high digestibility score.
So you see here, 90% plus.
I think poultry and beef are around 94%.
And then as we progress through these other forms, so legumes,
this would be beans and lentils and things like this,
you see a reduction here.
They're about 80% to 90% digested.
Also grains and other kinds of plants
foods, much less, around 70% to 90%.
The real deciding factor here between these two groups,
the legumes and the grains, is fiber,
because fiber gets in the way.
So in order for your body to actually get to the protein
it has to fight its way through the fiber.
So that's why you can see a little bit of a drop
down that digestibility.
Also, one thing I should mention about those animal proteins
is that they're complete proteins,
meaning that they have all of the essential amino acids
that your body needs.
So another word for that, when we look at animal proteins,
are high quality proteins.
So of those nine essential amino acids for humans,
a piece of steak, or chicken, or pork, has all of them.
And that can be really important when
we start to understand the rationale
behind different kinds of dietary practices
that people have.
We also see people choosing to have meatless diets, where
they're not consuming animal proteins.
Maybe they're not having meat or maybe they're
not having eggs, or fish, or dairy products.
So for those folks they really have
to have a good understanding of complementary proteins.
The idea here is that most foods contain at least a little bit
of protein, and different levels of amino acids,
and different types of amino acids.
So if people very carefully choose,
maybe a grain and a lentil or some kind of a legume,
they're able to pair the amino acid supplied
by each one of those foods to yield a complete protein.
So really you can look at this as complementary proteins,
or mutual supplementation.
A lot of people use these terms interchangeably.
The idea is that you're getting two different food sources that
are going to then make a complete protein.
And if you think about a classic type
of this complementary situation, it
might be a peanut butter and jelly
sandwich, because we have the proteins from the peanuts
and then also the grain, the bread.
And that's going to provide enough essential amino acids.
There are other ones that you could also think of,
so something like walnuts and pasta
would also be a good choice that falls in there.
Something like tomatoes and pasta,
that's not a complete protein, because we
find that those tomatoes don't provide the amino acids that
are lacking in the pasta.
So now when we look at protein requirements,
and this is a really tricky area for a lot of people,
and you see a lot of different recommendations
about how much protein people need.
People that are trying to grow muscle, maybe bodybuilders
or athletes, we see them over consuming protein
to a significant extent and it can cause problems.
So we're going to look at what happens
when people have too much protein.
But I just want to talk to you a little bit
about a baseline requirement for most
adults around their protein means.
So the DRI, Dietary Reference Intakes,
are set for the average person.
So for someone that is pregnant, they have their own DRI.
For a child, they have their own needs.
So again, for our purposes right now, we're
referring to an adult and what their protein needs are.
So it depends on body size.
There's really no significant difference between gender.
There's no significant difference between age
when we're talking about adults.
So you could have someone that is 19 years old
or you could have someone that's 50,
and the requirement is roughly the same.
There's very little basis for a difference there.
So for adults we see that 0.8 grams of protein per kilogram
of body weight per day is an appropriate recommendation.
Now most of us don't know our weight in kilograms.
We are familiar or comfortable with the metric system.
In health care you really, really
need to be very comfortable with metrics.
The whole health care system runs on metrics.
You will still see people referring
to how much they weigh in pounds but usually
in charting it's in metric.
So to figure out your weight in kilograms
you take your body weight and divide it by 2.2,
because for every kilogram it contains 2.2 pounds.
So again, our formula here is 0.8 or 8/10
of a gram of protein per kilogram of body weight.
And we see in terms of dietary placement
what percentage protein should make up.
It's about 10 percent of calories
should be coming from protein.
I want to just take a little step here and mention
that there are people that consume drastically
more protein.
And in your textbook, and we'll talk
about this when we talk about physical activity
and specific nutrient recommendations,
some of the protein recommendations
can be double the average that we're seeing here.
So instead of 0.8 grams per kilogram we're seeing 1.6.
Some people even recommend two grams
of protein per kilogram of body weight.
That's exceptionally high.
For people that are consuming significantly more protein
than the RDA, there doesn't seem to confer any advantage
around muscle building.
In order for your body to make use of all of that protein
you're consuming you actually have to work out.
And really we don't see people being
able to work out to that extent where
they can utilize all of that protein.
So you need the amount of protein
that your body needs and excess doesn't
mean that you're going to build more muscle.
So keep that in mind.
All right, I want to look at protein deficiency now.
And we see protein deficiency in the US,
but it's primarily a concern worldwide.
In the US we tend to consume more protein
than is required, and especially in the form of animal proteins.
Globally we see a dramatic difference
in the amount of protein that people are consuming.
And at normal levels, so they're consuming about 0.6
to 0.8 grams of protein per kilogram of body weight,
it's a completely healthy choice.
No worries there.
Our concern really is around people
that are consuming less than that.
And I just wanted to show you this graph because it shows
you different causes of death worldwide.
And so you'll see perinatal, so around the birth
or within the first couple of weeks of birth, mortality.
Other, which can be all the things we haven't noticed here.
Pneumonia, diarrheal diseases, especially in young children,
are a major killer, malaria, measles, and ***/AIDS.
When we look at all of these different causes of death
we see that undernutrition plays a significant risk.
So 53% of the diseases that we see here
are directly attributed to undernutrition.
And undernutrition, again, it's this umbrella term.
So it can be undernutrition around protein,
it could be around different kinds of micronutrients,
like Vitamin A or iron or things like that.
But in our context right now we're
going to focus on protein.
So when we see too little protein,
we have this term that really encompasses
two different diseases there.
It's called PEM, or Protein-energy Malnutrition
And this is a widespread nutritional problem
in the world.
And, again, this is an umbrella term.
And underneath that we have a particular disease
called marasmus malnutrition and then one called kwashiorkor.
And I'm going to tell you a little bit more
about these because I think if you watch the news
or you travel to other countries you're likely to see these.
And it's important to recognize and understand
what's happening in different populations.
So when we look at Protein-energy Malnutrition,
again, this is going to encompass
both marasmus and kwashiorkor malnutrition,
we see about 500 million children
facing chronic and severe starvation and hunger.
This is really significant and it comes down
to the number of children that are
dying per day as a result of this.
So you see this statistic here that 33,000 children
are dying each day.
More recent statistics point to this being much higher,
around 35,000 to up to 40,000 children dying per day.
And actually if we were to figure this out,
it's about one child every five seconds in the world.
And there are particular areas, regions, or even
countries where we see protein being a significant problem.
And Protein-energy Malnutrition is
very prevalent in Africa and also Southeast Asia.
I will mention that Central American has really
done very, very well.
And a lot of that is attributed to the work of someone
called Nevin Scrimshaw, who actually died a few days ago.
And his work looked at stunting in children, so
children that didn't have enough protein,
they were significantly shorter.
And he was able to find ways to change the foods they were
getting and raise awareness around nutrition
in places like Costa Rica, Nicaragua.
We also see the Middle East, and Southeast Asia,
I've already mentioned.
Now I want to look at marasmus malnutrition.
And you can see a little boy here.
We have this child, and just take
a minute to really look at his appearance.
He's very, very thin.
You can see his ribs.
His limbs are really just sticks.
And if we could see a little bit better, the quality the photo
may be a little bit poor, but his face even.
Sometimes you see sunken eyes, and the child
looks very, very, very thin.
Skin and bones, really, is often how people characterize this.
And we see this happening quite often in young children,
so between six months and 18 months, it's quite common.
And the person, again, really is just
skin and bones or stick person, and they
tend to look very old, like their skin looks old.
And this is really a result of inadequate food intake.
It has to do with inadequate energy.
So this child is not getting enough calories,
they're not getting enough vitamins, or minerals,
and not enough protein.
So overall this diet is lacking.
It's completely insufficient.
So we're seeing here just what we
think of as classic starvation.
And the person becomes shriveled and lean all over.
Now there are some different consequences
to marasmus malnutrition.
And with this we see that the organs
in the body and structures become really compromised.
Your body starts to eat itself, this catabolic process.
Normally, children are in this anabolic process.
They're building protein, they're building structures.
When there's not enough protein to build all these things
that we've talked about like tendons and bones and skin,
the body really has to stop that growth process.
And then also metabolism slows, so that child's body
temperature is often very low.
The body is basically shutting down.
They're on reserves.
And so they're going to stop any process that
isn't absolutely essential.
And there's very little fat on this child.
So protecting the child from cold or extreme temperatures
is really difficult.
And often young children have difficulty
regulating body temperature.
Now one saving grace, and I struggle
with this because in some ways it's not a saving grace,
is that a child that is suffering
from marasmus malnutrition, as the disease
progresses, they don't cry, because that
would take too much energy.
They don't engage in any physical activity that
isn't absolutely essential for life.
And I think in some ways, having been
in an international environment and seeing this,
I think it's a little bit easier for parents.
No parent wants their child to starve
but sometimes there just aren't resources.
And so if you can put yourself in the place of some mother
or father that's watching their child starve and is powerless,
you can imagine that it's just a very, very difficult process.
And these children are very lethargic.
They will just lay there all day.
They will sleep 22, 23 hours a day.
It's really quite tragic.
So a few more consequences, if the stuff we talked about
hadn't been enough.
Again, growth is going to cease.
The body really is going to start,
at some point, not only dismantling large muscle
groups, so things like leg muscles and arm muscles,
but also catabolizing organs.
And the heart is one that's very often compromised.
And the skin starts to lose its elasticity.
So normal little insults to the skin
that would be healed very, very quickly
can take days and days to heal.
And you see this increased risk of different kinds
of infections.
And so sores develop and things like
this that are very, very difficult to heal.
Now, if you think about the body, it's quite smart.
And if there's no food coming in your body says,
well, I don't need digestive enzymes.
Because remember, those are made out of protein.
So the body starts to stop production
of all of those different nonessential enzymes.
So even if we were to refeed that child,
the child is not going to be able to digest the food.
And all of that digestive tract starts to deteriorate.
And if we were to give the child supplements of some kind,
they would actually cause a lot more problems.
It's something called refeeding syndrome.
And it's actually something we've
learned a lot about after World War
II in the liberation of different kinds
of concentration camps, and also looking a little bit
at the progression of a disease called anorexia nervosa.
And we can kind of understand what happens in the body.
Over time we see that blood proteins
are going to be compromised.
I mentioned hemoglobin, it's that oxygen carrier
on the red blood cells, and the body
is going to stop producing this.
So the child becomes anemic and there's not
enough carrying capacity for the oxygen.
So the child is short of breath and it's very, very difficult
to even catch your breath.
If a child were to suffer some kind of an injury, break a bone
or have a catastrophic cut or laceration,
that stuff just is not going to heal.
And the list goes on, I'm sorry to say.
Antibodies are compromised.
So antibodies, remember our little agents
to fight off infections or diseases and keep us healthy,
part of the immune system.
And we aren't going to be able to produce those
if we don't have enough protein.
So the book talks about this example
and I really quite like it, about dysentery and what
happens when a child is suffering
from marasmus malnutrition and they're
confronted with dysentery.
Dysentery is caused for lots of different reasons
but different kinds of parasites can do this.
Also different kinds of bacteria, so amoebic dysentery
is quite common in some locations if you're a traveler.
So read that section.
And then also measles.
Measles were vaccinated in the US, most of us,
and if a healthy child contracts measles
they're probably going to be healthy within one
to two weeks.
They're going to recover fairly easily.
In the developing world, especially if a child
was poorly nourished and suffering from Protein-energy
Malnutrition, they can be dead from measles
within about two to three days.
And we see measles being a worldwide killer,
especially in populations where there's
limited access to nutritious foods.
So that's marasmus malnutrition.
And keep in mind this is about not enough calories,
inadequate vitamins and minerals, and not
enough protein.
So a very, very substandard diet.
This is really different than something
called kwashiorkor malnutrition.
So I just want to take a little bit of a look
here at how this presents itself in populations.
So we can see this drawing here, and I'm
going to come back to this and point out different features,
but if you've traveled or you've watched TV, or seen
some of these programs from developing countries,
you might see a child that looks like this.
And you can kind of see that she's got this belly here
that's kind of pregnant.
And so it's a very, very different presentation
than the marasmus malnutrition, and if we could see the face
there, it's a very different facial presentation too.
What's happening in the case of kwashiorkor malnutrition
is that the child is very often getting sufficient calories.
So they're getting enough energy from the diet,
but the diet is lacking in protein.
So a traditional diet that we would see causing or increasing
risk of kwashiorkor malnutrition might
be a millet based diet or a corn based diet.
And that's common in places in Central Africa.
Or you could see it with a highly vegetable based
diet, maybe in Southeast Asia, so maybe there's
rice and a whole bunch of different kinds of vegetables.
That's a diet we see in places like Thailand or Cambodia
or Vietnam.
And there's not a significant source
of protein, that's the real problem with that diet.
So again when we see the presentation,
we looked at the child that had kind of this pregnant looking
belly, and this is edema, so this is fluid
that's accumulated in this region.
And the reason this happens, and I'll talk about it again
in a minute, is that we don't have those different proteins
that are going to enable fluid balance
and allow fluid to stay compartmentalized in the body
where it should.
You can also see edema in the legs,
so a little bit of a swelling here.
Sometimes in the hands but not as common.
Generally if people are going to suffer edema it's in the feet
and also in the belly.
You could see some other kinds of changes as well.
Fatty liver is often a significant change,
and this has to do with the way that digestive processes are
occurring with a lack of protein.
And there are a few other things that we'll talk about as well.
But the real defining characteristic
is this large kind of edematous belly.
Now, I will say that you can see this presentation
in some populations that has nothing
to kwashiorkor malnutrition.
And you're going to be little grossed out here,
but it can have to do with parasites.
So you can see children who have a very, very large belly,
sometimes it's absolutely astounding
how large this belly can get, and it's
filled with parasites, different kinds of nematodes
or intestinal worms.
So when you see this presentation
there can be other reasons, just keep that in mind.
But let's progress a little bit and talk more
about kwashiorkor malnutrition.
So in some regards some of the symptoms
and the consequences we're going to see are similar to marasmus.
But the origin of this disease, we
see it occurring with populations of a certain age.
And it has to do with the next child that comes along.
So the baby or the child is being fed breast milk,
and then there's another baby and that baby
is going to get the breast milk.
So the older child is put on some kind of a cereal diet,
again millet and corn are very common, or rice,
and it's devoid of protein.
So that's where we see this opportunity
for that kwashiorkor malnutrition
to really get hold and take purchase in this child.
I will interject here that there are
a lot of reasons why people in other countries breast
feed in different ways that we do in the US,
in terms of the length of the breastfeeding duration,
and one of the reasons is that it's
an incredibly beneficial food source.
There are other reasons we'll talk
about when we look at pregnancy and lactation, in particular,
but it is a nutrient dense food, so the longer
a child gets breast milk, really the better off they are.
We really see a reduction in mortality levels
for children under five when they're breast fed much longer.
OK, so I want to look a little bit more
at some of these symptoms.
I've told you that you have the edematous belly,
so we see the fluid accumulating around the abdominal region.
And this has to do with a lack of protein carriers,
and also the opportunity for fluid balance.
Normally proteins have this job of holding fluid
in compartments in our body, and without those proteins,
because they're not coming from the diet,
the body is going to restrict its protein use
and cut out this particular operation.
So we see that fluid accumulating.
Then we see the fatty liver.
And what's happening here is that you
going to have fat that would normally not stay in the liver
start to build up there.
So think back to our conversation
about lipoproteins.
And the liver is really critical in making cholesterol
and these lipoproteins that carry
fat and cholesterol around the body.
So if we don't have that protein carrier,
that lipoprotein, all of that fat sits in the liver
and starts to accumulate.
So you can actually see some significant changes
in the size of the liver and it has
to do with all that fatty buildup.
You'll see some changes in the hair of the child, where
you aren't able to actually maintain
normal color to the hair.
It starts to take on sometimes a coppery appearance.
And I've seen this.
I was doing some work in India, and I saw this
in a particular population of Dalit people.
I only saw this particular problem in girls
because we know there's a real gender divide there,
and boy children and girl children
are not treated the same.
And their hair, instead of being this beautiful robust brown,
it turned kind of a coppery color.
And it was very, very distinctive
and it could be something you could pick out very easily.
Skin changes are also very common.
And, again, this is something that I saw in this population
quite often, is that the skin starts
to take on a scaly, patchy appearance.
And the sores that these little kids got,
in the course of being normal little kids, didn't heal,
and they got infected.
And the infections could be quite severe.
And you also saw this sometimes in the adults
as well because they didn't have a lot of protein in the diet.
It was a lot of rice.
Now in the US, these Protein-energy Malnutrition
problems can also occur.
We tend to think of them being in the developing world
but keep in mind that really extremely low income
populations can suffer from PEM, elderly folks.
And sometimes this is about dentition
or the quality of their teeth.
So if their teeth aren't very good
or they don't have dentures that fit well
and chewing is painful, they can start
to make different dietary choices
and maybe restrict their protein intake.
Homeless people and homeless children, of course,
and people suffering from anorexia nervosa,
and I mentioned this group earlier.
Now again I'm going to ask you to keep in mind that anorexia
nervosa is a psychological diagnosis.
Anorexia, which is someone who's just not eating,
is quite common in nutrition and it
happens for a variety of reasons.
It could be somebody's on a medication that really
diminishes their appetite and they're not hungry,
or it gives them nausea.
Maybe somebody undergoing a cancer treatment,
that's quite common for them to lose their appetite.
So folks that are at risk for PEM,
we can look at particular populations
that we're concerned about.
So people that are suffering from a wasting disease,
maybe you think of cancer or ***/AIDS.
These are two disease where we're really
intimately concerned.
And then also folks who are addicted
to different substances, drugs and alcohol.
There's also a link there.
And we see this opportunity that presents
itself, this synergistic effect.
So if someone is suffering from Protein-energy Malnutrition
and they have one of these wasting
diseases or another disease, they tend to worsen each other.
So we really want to follow people and make sure
that they're getting enough protein and enough food.
So we've looked at all the problems
that occur when we have too little protein in the diet.
We talked about PEM as being this umbrella name.
And then we have marasmus and kwashiorkor.
So what happens when we have too much protein?
Well, it has no health benefit.
We don't see people who consume more protein being healthier,
and really the opposite mechanism
occurs, where all that extra protein, especially if it's
a significant amount, tends to be really *** organs,
the heart, kidneys, and bones.
And if you think about the types of proteins
that we're consuming in the US, it
doesn't tend to be legumes and grains.
It's very often meat, and there's
a lot of extra saturated fat there,
so you also see increases in people's serum cholesterol
level.
So if you were to look at something like the Atkins
diet, which people are consuming a lot of protein and fat
and really, really limiting their intake of carbohydrates,
grains, and fruits, and vegetables,
and things like this.
You actually can see over time, and the literature
shows this, an increase in serum cholesterol levels
and an increased risk in heart disease.
Also that extra protein, if your body can't use it,
it's extra energy that you don't need,
so people that tend to consume more protein than
is required increase their risk of being overweight or obese.
We've mentioned that these different kinds of proteins
that Americans are choosing are really,
really implicated with heart disease risk.
I want to look a little bit about some different choices
people might make around protein.
We know that protein is critical in nutrition.
We want about 10% of your calories coming from protein.
And there are advantages to animal proteins,
and there are advantages to legumes,
or beans, or vegetarian proteins.
So we want to look first at the advantages from animal protein.
Two of the ones that I'm most concerned with
are B-12 and iron.
And B-12 can be a struggle for people who are vegans.
B-12 is a vitamin that's only found in animal products,
so it could be a piece of steak, it could be a glass of milk,
it could be a piece of cheese, or an egg.
OK, those are the only sources of B-12.
You can get it from nutritional yeast,
but some purists say that, well, nutritional
yeast, that's an organism as well.
A lot of foods that are created especially
for vegans or vegetarians are fortified
with B-12, which is really I think
it's a huge step in the right direction.
Otherwise people could take a supplement,
and we'll talk about that a little bit more
when we talk about vitamins.
And then iron, of course.
And globally, 80% of the world is iron deficient,
or has suboptimal intakes of iron.
This is a critical issue for women,
especially of childbearing age.
We see that those protein-rich foods,
whether it's a steak or some chicken or something like this,
they lack vitamin C and folate.
And these are two important vitamins.
Vitamin C helps you to fight different kinds of illnesses,
it's an antioxidant.
But it's also implicated in collagen development,
keeping bones strong, keeping skin strong.
Folate is a B vitamin, and this one
is really critical during pregnancy.
It's involved in cell proliferation.
So you think about pregnancy and growing a fetus,
there's exponential growth there,
so we need folate for that as well.
It's also important in keeping you healthy overall.
Now some advantages that we see with legumes or beans,
so it could be kidney beans, or garbanzos, or lentils,
or something like that, and even soy products, really
the proteins there are considered
to be equivalent to meat.
There a lot of advantages to this
because it doesn't come along with a lot of saturated fat.
And other kinds of things that maybe we
just don't need to have.
And these foods, the legumes, are also an excellent source
of a lot of the B vitamins, especially folate.
And they have iron.
It's what we consider non-heme iron, which
we'll talk a little bit about.
But non-heme iron means that it's
absorbed at a different rate.
And then calcium.
Which those are generally lacking
in some of those other meat proteins.
But legumes aren't the end of the story.
Legumes tend to lack vitamin A and vitamin C,
and of course they don't have B-12
because B-12 is only supplied by animal products.
So there are a lot of things to consider
when we're choosing a protein, whether you're a vegetarian
or whether you're eating meat.
We know that portion control is a really big issue, especially
with animal proteins.
A serving of beef or chicken or fish is three ounces cooked,
and very, very often people overestimate
their protein needs and overeat the amount of protein that
is required by their body.
And it can have pretty significant health risks
with that.
The recommendation from the government right
now is that people continue to eat meat
if that's the lifestyle that they choose,
but also consider going meatless one or two nights a week.
And keep those portions within the appropriate guidelines.