The first group of macronutrients we'll discuss are the carbohydrates.
Carbohydrates are found in a variety of foods and are essential nutrient.
Regardless of what some fad diet may tell you, you do need carbohydrates.
Though some of them can be considered to be more nutritious than others.
Dietary carbohydrates are primarily plant based macronutrients.
Animal derived foods other than milk, don't contain a preciable amount.
Plants build carbohydrates through photosynthesis converting to carbon
dioxide, water and solar energy into glucose and oxygen.
Thereafter, glucose can be stored in glucose chains like starch or fiber or be
converted to fructose. We'll talk a little more about each of
these nutrients shortly. Monosaccharides are single glucose
molecules or fructose molecules. I can see here glucose, is a 6 carbon
molecule, as is Fructose. Yeah, tou'll see that the ring structure
of fructose has one more carbon outside of it attached to the OH group while
there are all carbons in the ring structure in glucose.
Three mono-saccharides foods are Glucose and Fructose.
Glucose, while found in fruits, vegetables and honey, is mainly thought
of as blood sugar. Fructose is more abundant in honey,
fruits and vegetables as well as corn derived sweeteners like corn syrup.
Although maltos is obtained from the diet, its derived from the breakdown of
disaccharides and polysaccharides during digestion, so it is also an important
monosaccharide, but you wouldn't consume it on it's own.
Table sugar and the sugar that's added to food are extracted from the plants sugar
cane and sugar bead. Lactose or milk sugar is made up of one
molecule of glucose also, like sucrose is.
And one molecule of galactose. Galactose is in all dairy products.
And, like all disaccharides, is broken down to free monosaccharides of
digestion. A specific enzyme is needed to break down
each disaccharide. In the case of lactose, you need lactase.
People who don't break down lactose, into pre-monosaccharides, lack this enzyme.
And they are, considered to be lactose intolerant.
The lactose molecule can't be absorbed, into the body, if it's not broken down,
so it's going to be lost in the feces, typically causing diarrhea, in the
lactose intolerant individual, that chooses to consume, a lactose containing
product. Starch is how plants works carbohydrates,
the amount of starch and the ratio of amylose to amylopectin will vary from
plant to plant. Humans and other animals store their
glucose as glycogen. They store primarily in the liver and
muscle tissue. Like amylopectin, as you can see in this
image, glycogen is branched allowing for efficient glucose storage in a small
amount of space. Even when consuming meat, which is muscle
tissue, there's little glycogen in the foods we eat.
Glycogen in animal tissue is actually broken down very quickly after the animal
is slaughtered. Fiber, the last category of
polysaccharide we'll discuss, is indigestible by humans.
It's primarily found in figel chains, and the bonds between the sugars are only
broken down by bacterial digestion. You can see here the slight chemical
difference between starch and cellulose. Herbivores like cows, horses, deer they
can actually get energy from fiber because they're got large amounts of
bacteria that can digest the fiber and their digestive systems are designed to
absorb this free sugar. Even though we humans and other omnivores
and carnivores do have intestinal bacteria, much of it is found in the
large intestine. That's not a place where a lot of
absorption takes place. So by, fiber does have a function in our
bodies, but it's not to provide glucose. The reason we can't just break this fiber
down is because we don't have the enzymes we need to break this molecule.
This slight chemical difference here you can see makes a huge difference in
nutrition. So when we talk about we are what we eat
then chemistry and food go hand in hand. We can see how little differences in
chemistry change how we, the organic organism, utilize our food.
There are many types of fiber, and we can divide them into the insoluble and the
soluble or viscous. Fibers like cellulose, hemicellulose, and
lignin are insoluble fibers. They're not going to dissolve in the
water of our intestine. They're part of a plants cell wall, they
help give the plant structure. And within the food that we eat we find
insoluble fiber in rice, wheat, other whole grains, fruits, vegetables, legumes
and seeds. Fibers like pectin, gums, mucilages, and
glucans are soluable or viscous, so they will dissolve in any base environment.
These are located within the cells of a plant wall, or within the cells of a
plant, and are included in whole grains, fruits and vegetables, legumes, and
seeds, and the husks of plants. In the food industry, these fibers are
extracted from plant sources and used as food additives.
We call this functional or added fiber. So, the food we eat can have dietary
fiber, inherent fibers, something that's natural within it, or it can be added to
our foods. You can actually even purchase simple
fiber dupplements like Metamucil. If you go to the grocery store, look at
labels and see what has added fiber to it.
Again this is done at the factory, not by nature.
So why would you manufacturer want to add fiber to his product? Does it make it
taste better? Does it make the product more shelf stable? Well, it actually,
potentially make the product more healthful.
Granted you could choose the high fiber diet that's high in natural fibers but
for some people, they'd rather choose a product where it's been added.
Maybe it's something they really like to eat, no.
it's a little healthier. Fiber does a lot of good things for us
human beings even though we can't digest it.
It slows stomach emptying and in this manner it extends the time you feel full
or at least satisfied after a meal. It's very important for good health And
companies knowing that customers are looking for some of the nutritional
benefits, realize that this could be a selling point.
And that's why they've added it to their foods, and it is manufactured and
marketed for it's dieters, individuals with constipation, individuals that have
trouble meeting their fiber needs, and diabetics.
So here we can see the intestinal tract and as I briefly mentioned already, fiber
helps keep this whole system healthy. Just like your skin cells, our intestinal
tract has cells on the walls of the system.
As we go down the stomach, through the small intestine, large.
Intestine. These cells turn over on a regular basis.
And fiber helps keep these cells turning over, sloughing off old, dead, less
functional cells. Also fiber helps exercise the stomach so
it keeps the muscles of the intestine working hard just like when you go for a
walk you might exercise your muscles, fiber is exercising In your gut muscles.
In addition, fiber will slow digestion down, at the level of the stomach.
But speed digestion up, further down the road.
Down in the colon and the large intestine.
What this means, is, that, it will slow digestion at a point, where we want to
sort of control what foods getting to the next step.
We can also control how much sugar is getting into the blood, when we slow
digestion, by eating More fiber. Later when we want the waste products to
move through the system, we want fiber to help that to happen.
Another benefit of fiber is in the prevention of diverticulosis.
As I mentioned fiber helps break down these cells, while diverticula are
pouches that form along the colon. this is when our gut becomes unhealthy
and can become infected and inflamed. By promoting regularity keeping the
muscles of the gut healthy and strong and sloughing off old gut cells.
Eating fiber prevents the regression for development of Diverticular.
Another benefit of fiber and another way that manufacturers market products with
added fiber is in the bile system. So bile is an emulsifier.
When you eat fat, you're taking a lipid component and introducing it to an
aqueous environment. Your stomach fluids, your intestinal
fluids, these are all aqueous products. So when you eat fat, we need to make sure
that the fat just doesn't stick together and keep itself in one spot.
So if you imagine taking some olive oil and dumping it in a glass of water, you
would see that the olive oil would stick together.
The same thing would happen in your stomach and this would impair the
breakdown and digestion of your fat, and this is where bile comes in.
Bile emulsifies this fat, keeps it into smaller components and allows for
improved digestion and breakdown of the fat.
Bile as this figure illustrate, actually comes from cholesterol.
So as we consume food we use our bile. We need to produce more.
And when we eat more fiber this bile actually finds the fiber in our
intestinal tract and more of the bile will be excreted from the body.
So by eating more fiber, you will bind some of, some of this bile off.
Excrete more of it, and therefore you're going to need to make more bile.
Again, you still need the bile to break down the fat you're going to eat later.
So a liver will convert cholesteral to bile.
And through this system, release more bile into the intestinal tract where it's
needed. So by consuming more fiber you use up
more cholesterol to generate bile. This is why you might see on a cereal box
with high fiber, this claim may lower help may help lower cholesterol is
because of this row of cholesterol, bile and fiber.
So what kind of carbohydrates are good carbohydrates? We know that there are
diets out there that ask us to avoid carbohydrates, that they're less
nutritious, that they're less filling, that they're negative things that are
going on with carbohydrates and we're going to talk a little bit about that in
a subsequent lecture. But are carbs bad? I'll let you decide
that but for now I'm going to let you know that some carbohydrates are very
good. Whole grains like brown rice, legumes
like black beans, vegetables And fruits have healthy carbohydrates.
They come along with lots of vitamins and minerals that your body needs.
They come along with fiber, that will help do all of these things that I've
mentioned. And they're lower in sugar, which,
although it tastes good, is not as nutrient rich as these complex.
Carbohydrate product. Certainly fruit sugar is not a complex
carbohydrate, but it still comes along with a lot more, vitamins and minerals,
than a candy bar would. On the flip side, we want to avoid, the
simple sugars. Especially added sugars.
And the sugar recommendations, as you may have already read, are to consume less
than 25%, of our energy, in these extra calories.
In these sugary components. So while some of these foods here may
look yummy, they're not as nutrient dense as some of the fruits and vegetables I
mentioned earlier and while they can be part of a healthy diet, we want to make
sure we moderate how much we consume. Even seemingly healthy foods can have too
much sugar, and therefore be less healthful.
It's important to read labels when you're trying to make healthy food choices.
This is just one example. So, you have the option to choose fresh
pineapple or canned pineapple. When you look at the canned pineapple,
they have canned pineapple in juice or in heavy syrup.
So let's look at the nutritional differences here.
Just take a minute to look this over. So all of these products have the same
amount of fat, no cholesterol, similar sodium content all though we see a slight
uptick in the sodium in the heavy syrup can, but there's a huge difference, not
only in carbohydrates, but in sugar and calorie.
So, our friend fiber, not much different. Slightly lower in those canned foods,
because there's a little more fiber in that fresh fruit, but the sugar
difference is significant, more than twice the sugar of fresh pineapple in the
juice pineapple can. And 4 times, almost 4 times the sugar in
a heavy syrup product. And you can see the impact this is going
to have on the calories. So read your food labels.
Why would you need a product in heavy syrup? Perhaps if you want to keep canned
pineapple on hand, it's going to less perishable but certainly, at least,
choosing the pineapple in juice is going to be The healthier option.
If you're going to eat the pineapple right away, of course the healthiest
option would be the fresh pineapple. And the amount of carbs in our food and
the amount of sugar in our food, reading those labels like I just mentioned is
going to be most important in someone that has diabetes.
You'll be watching a short video on the diabetes process, what happens in
diabetes and what happens with the carbohydrates.
But here's just some basic information to get started.
In an individual diabetes, their body is not processing carbohydrates as well.
So, we nutritionists help individuals moderate their carbohydrate intake, by
teaching someone how to actually count carbs.
So when you do your diet tracking you can go back and look and see how many carbs
you ate per meal and get an idea of what that would be like So when we count
carbs, we don't want to make it too complicated.
Granted, you could read every label, you could track your diet and get it down to
the point .01 of carbohydrates per meal. But in general we categorize
carbohydrates by 15 grams. For every 15 grams, we count that as 1
serving of carbohydrate. And for the individual trying to manage
their diabetes, we would give them guidelines of how many servings of
carbohydrate they should consume per meal.
So review this list. You can see some foods here with 15 gram
carbohydrate servings. Specifically if we look at meal planning
for someone with diabetes, their breakfast may consume 45 grams of
carbohydrate. This would be 3 servings.
Their lunch might contain also 45 grams or 3 servings.
Dinner may have more, four servings or 60g and the snack only 15g or one
serving. Now certainly you could switch this
around if perhaps you like eating a larger lunch.
You could have 60g or four servings at lunch and then only 3g, three servings or
45g at dinner. This will total 165g.
When it comes to carbohydrate counting, we do have those guidelines, as I showed
you in the slide previously, that had some basic numbers for different foods.
But it may also mean that you're measuring your food.
For example, pasta. That's a food that might be easy to
over-indulge in before counting our carbs.
That would be a good food to go ahead and measure.
that's compared to something like an apple where you can sort of estimate the
size of the apple and consume That one apple.
Rice would be another one that we'd want to go ahead and measure.
Other foods like slices of bread are easy to count.
So counting and then using your measuring tools can help in managing diabetes
through the carbohydrate counting process.
Alright, now please go to the following link to learn a little bit more about
blood sugar, diabetes, and the management of glucose in the normal individual and
the individual with diabetes.