This week we are learning about the vitamins.
We can classify vitamins as either fat soluble or water soluble.
So, think a little bit about the digestive processes that we talked about
when we, you read over the different text on fat soluble vitamins.
Structurally, fat soluble vitamins look like other fat.
We can see the similarities here between the carotene retinol and a simple fatty
acid. They're absorbed into lacteals along with
our fat. And so, if you don't eat fat, if you actually physically try to not eat
any fat at all, you would not absorb your fat soluble vitamins.
I'm just going to go over some key concepts of each of the fat and water
soluble vitamins but do continue to read your texts and the links I've provided to
the Office of Dietary Supplements for complete information on each of the
vitamins and minerals. In the case of Vitamin A, it has a
significant role in our visual cycle. It's actually a part of the compound
Rhodopsin. The rod cells are very important for
seeing in the dark. They're very sensitive to light and so
you only need low levels of light to activate your rod.
And so. When light hits these Rhodopsin
molecules, the retinal, the vitamin A in the compound will actually change it's
structure and send a signal to the brain, with results and sight.
This retinal does need to be recycled and returned to the retinal form to continue
to be activated. In vitamin A deficiency, long term, one
can actually develop night blindness, where one cannot see in low level light.
To get a little bit of an idea of how vitamin A works with these rise in cones
or how vision works with the rise in cone, vitamin A on the rise, you can do a
little experiment. So this little experiment you can do by,
standing in a dark room that's located right next to a bright room, or right
next to a sunny day outside. What you do is stand in this dark room
until your eyes adjust to the light. Do take note of what you can see and how
well you can see. Next, go outside, or into the bright
room, for just a few moments. And then, go back inside.
What you'll notice when you go back inside, is that everything's darker, and
you can't see as well. Now, your eyes will readjust, over time,
and you'll see again. Now this isn't just because of how your
pupils are dilating. This is also because when you went from
the dark environment to the bright environment, you activated so much of
that Rhodopsin that you exhausted it. And as you went back in your had to
quickly regenerate that compound. To able, to be able to respond to lower
levels of light. Good, vitamin D.
Vitamin D's key concept is that we can actually synthesize it.
It still is an essential nutrient, because we don't make enough to provide
our bodies complete needs and depending on how much time you spend outside you
may need. More or less.
Depending on where you live you may need more or less.
Vitamin D is actually generated from cholesterol in the skin.
The ultraviolet radiation from the sun activates the cholesterol and it's.
Processed in a 2-step, sequence in the liver and in the kidneys to form the
active form of Vitamin D. So, going outside can help maintain
Vitamin D levels and individuals that spend less time outside do need to get
more Vitamin D from their diet. In addition, people that live in areas of
the world where there's less sunlight, and that could be farther from the
equator or that could even be in a city where building block a significant amount
of sunlight. These people will also need to eat more
vitamin D. Vitamin E's major role is it adds the
anti-oxidants, powerful anti-oxidants, both in food and body so it can actually
work on, in protecting foods from becoming rancid.
It acts by neutralizing free radicals by donating one of its own.
And stopping the destructive processes of oxidation.
We talked a little bit about the susceptibility of polyunsaturated fatty
acids to oxidation and here we can see again where Vitamin E could play a role
in protecting these fatty acids. So, if you do eat more omega 3 fatty
acids, more polyunsaturated fatty acids, you may also want to make sure that
you're Consuming enough vitamin E. A key concept for vitamin E is its role
as an anti oxidant, Vitamin E has the capacity to neutralize free radicals and
reduce oxidation by donating once of its own electrons By meaning it can actually
be used in foods as a preservative. And it's a very healthy nutrient to take
in if you are consuming more polyunsaturated fats.
Remember, polyunsaturated fats are more susceptible to oxidation than saturated
fats. Vitamin E when it acts as an antioxidant.
Can actually, is actually becoming oxidized itself.
And Vitamin C can couple with Vitamin E in restoring Vitamin E's activity.
So as you read a little about vitamins and minerals.
Think about how they all play together as well.
One thing that we've not mentioned here is selenium.
Selenium is also very important in this cycle here.
And so we see having sufficient Vitamin E, Vitamin C, and selenium is important
in producting our, in protecting our body from oxidation.
Vitamins Ks primary role is in blood clotting.
A key concept I want to talk about in this is actually the role and balance of
vitamin K in blood clotting and the use of blood thinners.
So look over the slide for just a moment. You can actually go ahead and read in
your text about exactly what's happening in this clotting process, but overall,
Vitamin A, K is needed for clotting to occur.
When Vitamin A is utilized, it is in the inactivated, and needs to be refreshed.
Normally, you eat more Vitamin K to have a continuous supply of this.
molecule for the clotting process. Now, if you clot too much you might be
put on coumadin or blood thinners. Coumadin acts by blocking the recycling
of Vitamin K, therefore reducing available active Vitamin K.
When someone is put on Coumadin, they need to balance their vitamin K and their
intake of vitamin K foods with their medication.
Now in some cases Physicians may actually recommend people avoid most Vitamin K
rich sources. A dietician, however, would much rather
see a more of a balance happening. Now certainly, it might be dangerous if
this balance wasn't maintained. And that's likely why physicians tend to
afford the side of caution in saying, individuals on blood thinners should
avoid vitamin K rich foods. Blood thinners actually act very much
like. Rat poison, they are pretty much the same
thing and so when you give those types of rat poison to rats you kill them by
bleeding them to death. By blocking this clotting pathway.
So if you ever give a rat blood thinners and you don't want to kill him after all,
just feed him some Vitamin K and everything will be okay.
Okay, hi so let's briefly go through the water soluble vitamin, please do read for
the details of these. Water soluble vitamins are soluble in
water and they are absorbed and go directly into our blood.
Thiamin, Riboflavin and Niacin work together in our metabolic processe, look
for them coming back when you learn about metabolism.
We might not be calling them thiamin, Riboflavin or Niacin We'll call them ttp,
fad and nad. They're very important in carrying
electrons and hydrogens to the electron transport chain allowing us to produce
energy. Vitamin B6 is very important in protein
metabolism. It's essential for the synthesis of
non-essential. Amino acid.
Folate and Vitamin B12 are very important in what's termed The One Carbon Metabolic
Processes. Now this might look like a pretty complex
figure, don't be overwhelmed by it, let's just focus in on Vitamin B12, which is
right in the middle of the figure and Folate, which is actually Was to here as
THF, which stands for tetra hydro floric is one cycle here is responsible for
gaining equation in DNA synthesis. DNA Methylation goes on to be responsible
for one hundred reactions in the body, DNA synthesis is crucial for maintenance
of the human organism, but even more so it's very important in growth and
development, especially in fetal growth and development.
Folic acid and vitamin B12 are very important nutrients.
In pregnancy, and actually in the United States, fortification of our grains with
folic acid was started in order to produce the incidents of birth defects
affected by folic deficiency. We can look a little closer at vitamin
B12's role in this process. Vitamin B12 is needed for the conversion
of Homocysteine to Methionine. Vitamin B12 acts as a carrier for
tetrahydrofolate to convert. To transfer a a metyhyl group from
itself, Homocysteine generating Methionine.
In both folate and B12 deficiency, we will see elevation from Homocysteine.
Now, if you eat enough folic acid, or enough folate but not enough B12,
Homocysteine will still go up. But the left side of this whole
psychopair won't be affected. So with plenty of folate you'll still
have DNA synthesis. But the recycling of that folate in the
cetner of this diagram will stop. Will stop and trap the methyl group from
5 methyl Tetrahydrofolate, - 5-CH3-THF to keep it back and will that methyl group
trapped there and will impact DNA methylation.
Now, if you eats lots of B12 and not folate, you won't provide that methyl
group and you'll impair both systems. The key concept in the case of Vitamin C
is Vitamin C's role in collagen formation.
Collagen is part of various tissues in the body.
When we look, we talked a little bit about oral health in our carbohydrates
lecture, well Vitamin C is also important in maintaining oral mucosa as well as
connective tissues. When we don't form proper collagen in
vitamin C efficiency. You can actually see results such as
bleeding of the gums, increased bleeding of the gums and this is because that
connective tissue is not strong enough to keep fluids from coming out.
You can learn more about Vitamin C and all of the vitamins I've talked about
thus far, in your text, as well as one linking to fax sheets from the Office of
Dietary Supplements. The Office of Dietary Supplements has
information for both the health professional and for the consumer.
If you look here, you'll notice I have actually referenced you to the health
professional links, that is just going to have more extensive information than the
ones for the consumers.