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in this first lecture on vitamins I'll
be introducing you to differences
between water soluble and fat soluble
vitamins and then we will go on to
explore the details of each that you
should know for your exams
first we'll take a look at the common
features of water soluble vitamins first
of all they are hydrophilic hence the
reason that they are water soluble which
means that we need them only in small
amounts and that any excess is going to
be excreted in the urine so rarely will
we see a toxicity of water soluble
vitamins but more likely a deficiency
because there are no backup stores in
the body the exception to this rule are
in vitamin b12 and b9 which are stored
in a fairly significant amount in the
liver so that they are available for
future use
so let's take a quick look at all of the
vitamins water soluble vitamins that
we'll be covering this is all the B's as
well as the vitamin C and you have names
associated with each but let me caution
you or let you know that these names and
numbers are not things that you need to
match together anytime they mention on
your exam one or the other both pieces
will be there of course by the time you
are done with learning these specimens
you probably will know the names as well
as the letters associated with them for
each anyway we will then cover details
of fat soluble vitamins fat soluble
vitamins there are many less of them so
much less to handle there they are all
hydrophobic and hence the fact that they
are fat soluble again necessary in small
amounts any excess here will be stored
in the liver or fat because they are
stored in the liver or fats we can
actually experience toxicities with fat
soluble vitamins but deficiencies are
much
less common because there's generally
three to six months worth of storage in
the fat and liver tissues so water
soluble vitamins water soluble fat
soluble vitamins fat soluble simple
enough right
here's how I remember my fat soluble
vitamins
you can either remember that they are
all of the vitamins that are not B and C
or you can remember them as a ke and D
again the names are always going to be
associated with the letters in the case
of fat soluble vitamins the actual name
can change dependent on the form of the
particular vitamin for example we might
have vitamin d2 or d3 d3 is the
cholecalciferol and the way that I
remember these is by imagining a big fat
lady laying on the beach naked so and we
add that in there and then aka e and D
and I can sort those out pretty good
visual to keep that in mind we use that
with students it seems to work so big
fat lady laying on the beach stuff an N
in front of it and you've got or naked
fat lady laying on the beach cannot
include a picture here so that's all
good I'm sure you will keep that in your
memory now the key here with absorption
for fat soluble vitamins is they are fat
soluble and so they are generally going
to be bound up in fats which means that
we require pancreatic enzymes in order
to absorb them right they're absorbed
very chylomicrons in the small
intestines so any disorder that
interferes with pancreatic enzymes will
create issues with absorption of fat
soluble vitamins now if you have a
decrease in fat absorption clearly as
recovered you'll have a decrease in fat
soluble vitamin absorption also if you
have a decrease in
that absorption one of the main symptoms
is guess what well one of the main
symptoms is steatorrhea maybe you
haven't heard that word maybe you have
but that ends up meaning basically
greasy stools so fat in the stool
steatorrhea can result or can be a good
indicator that someone may have problems
with the pancreas or fat absorption and
or and potentially fat soluble vitamin
absorption so oily stool smells really
bad bad symptom to have anyway many of
the causes of steatorrhea are here in
the table as you can see most of them
relate to issues with the pancreas or
for example with Crohn's disease and
celiac disease absorption across the
intestine so cystic fibrosis it comes up
because with cystic fibrosis we have
decrease in in fluids so we have the
stickiness which actually inhibits the
secretion of pancreatic enzymes so
that's one of the symptoms also of
cystic fibrosis is decrease in fat
absorption and so keep in mind that
anywhere we're talking about absorption
issues we could have a problem with any
of the vitamins but particularly any
issues of the pancreas we can have an
issue with absorption of fat soluble
vitamins so on that note I'd like to
share with you an interesting situation
you can see in the above image that fat
digestion occurs normally using the
enzyme lipase right secreted from the
pancreas and it breaks the fatty acid
chains away there are a number of drugs
on the market presently for prescribed
and over the counter for weight loss
that all fall under the umbrella of
orlistat
now what orlistat does is theoretically
cuts the amount of fat absorbed in
and so we see that it interferes with
the lipase enzyme and leaves the fats
intact or triglycerides intact and I bet
that you can guess what one of the major
side effects of drugs like a lie or or
Lestat's are well yeah you've got it
stay at area not such a great symptom
and whether they're effective or not
potentially they are if you see the
patients are having increased levels of
exercise and reduced caloric intake so
they should definitely be prescribed
with lifestyle modifications also so in
short this was a very brief introduction
to the differences between fat soluble
and water soluble vitamins and I look
forward to seeing you in the next series
of lectures as we highlight all the
aspects that you need to know for your
exams
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you