vitamin d what can't it do right well
actually
what does it do in this video i'm going
to tell you exactly what you need to
know
about the sunshine
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how's it going guys my name is richie
kerwin and i'm a nutritionist and
nutrition researcher
at liverpool john moores university and
you're watching the my protein youtube
channel
this is a channel that brings you need
to know info on how to fuel your body
and train
to be your strongest self today we're
going to talk all about a vitamin that i
think
most people should consider
supplementing with vitamin d i'll tell
you how we make it
why we don't make enough what it does
and how much you should consider taking
as always i want to point out that i'm
not recommending
any particular vitamin d supplements
what i am going to do
is talk about how vitamin d works and
what to look out for
when looking for a supplement let's
start with the basics vitamin d is a fat
soluble vitamin which means it dissolves
and can be stored in fat
that makes it different from
water-soluble vitamins like b and c
because they can't be stored in our
bodies and any excess that we eat
gets peed out fat soluble vitamins can
be stored in our bodies this is good
because it means we can store any extra
vitamin d we make or we get from the sun
but it does have one negative side
effect
if we eat way more than we need we can
store so much that it can become toxic
in the body and have some serious
negative health effects this is called
hypervitaminosis
d and you do not want it to happen to
you just to give you all an
easy reference value the recommended
daily intake for vitamin d3 in the uk
is 10 micrograms as there are some
different forms of vitamin d we also
measure using
international units which standardize
the effects of the different forms of
the vitamin
10 micrograms of vitamin d is the same
as 400
international units vitamin d is a very
interesting vitamin because we can make
it in
our skin when we're exposed to sunlight
specifically ultraviolet b
or uvb rays in our body we use
cholesterol to form a substance called
seven dehydrocholesterol when our skin
is exposed to sunlight the seven
dehydrocholesterol just under our skin
gets converted to pre-vitamin d3 which
then
gets converted to colicle this then gets
converted to calcidial in the liver
otherwise known as 25
ohd tree which is what we use to measure
serum vitamin d levels
finally this gets converted to the
active form calcitriol
in the kidneys try dropping that into
dinner conversation sometimes
you are guaranteed to never get invited
back the great thing about producing
vitamin d in our skin
is that our body has a feedback system
in place that stops you producing too
much vitamin d from sunlight
so there's no worries of producing too
much from sun alone the problem with
producing vitamin d from sun is we just
don't get enough of it you see someone
could
probably make enough vitamin d from
sunshine if they get up to 30 minutes of
sun exposure
twice a week over their face arms and
legs if they're very fair-skinned
and if they're relatively young do you
meet all those criteria the problem is
we all spend a lot of times indoors or
pretty much
all of 2020 and when we do leave the
house we're usually fully clothed at
least i hope you are
we often travel around in cars glass
filters out uvb rays so you're not
producing any in the car
and if you live far from the equator
like in ireland or the uk we only get
enough uvb
rays to produce vitamin d in the summer
on top of that
if someone has a darker complexion like
someone of sub-saharan african or
south indian origin the melanin in your
skin makes producing vitamin d
much harder compared to people with
lighter skin especially for those living
far away from the equator
and if you're older we know that older
people aren't able to produce vitamin d
from sunlight
as well as younger people so getting it
from sunlight isn't easy what about from
food
well that's an even worse story
unfortunately there are very few good
sources of vitamin d in our diet
it's found in meat eggs or dairy but not
in high amounts to give you an idea of
how much is in meat depending on the cut
and the animal's feed
beef steak has around 5 micrograms of
vitamin d per kilo
which means you'd need to eat two
kilograms of steak just to get your
daily amount of vitamin d dairy products
often have
less and that's why they are often
fortified with vitamin d
to prevent deficiency egg yolks are a
little better but you'd still need
around 250 grams of pure egg yolk
just to meet your daily dose now animal
liver can be a good source of vitamin d
as can some oily fish and fish liver but
not many people are willing to eat fish
liver to get enough vitamin d as for
non-animal sources
you can get mushrooms that are grown
under special uv lamps that increases
their vitamin d content
but that's about it in fact the form of
vitamin d produced in mushrooms and used
in some supplements
is called ergocalciferol or vitamin d2
and while it still is a form of vitamin
d
it's not as efficiently converted to the
active form as vitamin d3 and this is
why vitamin d deficiency is so
common insufficient vitamin d is
considered to be serum levels below
50 nanomoles per liter so if you have
above that you're considered to be
vitamin d sufficient the problem is
more than 40 of europeans have levels
below that
and actually 13 have levels below
30 nanomoles per liter vitamin d
deficiency is actually considered to be
a global health
problem so we don't get enough why does
that even matter well like i said
vitamin d is a very special vitamin and
one of the reasons for that is something
called the vitamin d
receptor the vitamin d receptor is a
nuclear receptor which means that
vitamin d
binds with it and then regulates the
expression of specific genes
that's important because the vitamin d
receptor is found in virtually every
tissue in the body which means that
vitamin d has a big
role to play in our health one of
vitamin d's most famous roles is in
bone health and this is because of its
regulation of our blood calcium levels
vitamin d helps to increase the
absorption of calcium from our gut
when blood calcium levels drop it helps
to absorb more calcium from our kidneys
before we pee it out and can even take
calcium from our bones if we need it
this is because
the level of calcium in our blood needs
to be maintained at a specific level
and it's essential to many processes in
our body
like nerve transmission and muscle
contraction because of its role
in calcium metabolism vitamin d is
essential for building a strong skeleton
and lower vitamin d levels are
associated with lower bone mineral
density
and a greater risk of fractures in both
younger and older people but vitamin d
is
so much more than bone health it's so
important that low levels of vitamin d
are associated with higher rates of
cardiovascular disease high blood
pressure diabetes
and other cardiometabolic conditions
this is because vitamin d has an
important role to play in both
insulin sensitivity how we process
glucose and the health of our body's
fat stores on top of that vitamin d has
a massive role to play in our body's
immune system
helping us to fight off disease and low
vitamin d levels are even associated
with greater risk of autoimmune disease
you've all probably heard of vitamin d
being really good for upper respiratory
tract infections this
is true as supplementing is associated
with lower rates of infection but many
of these studies aren't based around
covet infection just respiratory tract
infections in general here's an
important aspect of nutrition science
we can say very little for definite when
we talk about the effect of a specific
nutrient on a specific disease
we can only talk about risk so for
example we can't say that
having sufficient vitamin d levels would
prevent someone from getting a disease
but we can say that it reduces their
chances of getting
it reduces the potential risk but it's
not a guaranteed protection that's
something people get wrong with
nutrition science
all the time vitamin d also has a major
role to play in
muscle growth and higher levels of
vitamin d are associated with higher
levels of testosterone
greater muscle mass strength and
physical function because of all this
higher levels of vitamin d are also
associated with a lower risk of death as
we age
so it sounds like vitamin d is pretty
important right and seeing as we don't
get much from our diet or sunlight
especially in ireland and the uk
supplementing is probably a good idea
here's the thing
a lot of vitamin d supplement trials
don't show any benefits and that's
probably because they don't supplement
enough to raise serum levels remember
vitamin d insufficiency is when serum
levels are below 50 nanomoles per liter
so getting your levels above that is
important if your vitamin d levels are
quite low
that might take some time that's why
many people like to get their vitamin d
levels tested so they know what their
current levels are
and then they can retest after a year to
see if their supplementation has worked
that's also a really good way to make
sure you don't get too
much vitamin d which can be really bad
for your health
from a dosage perspective the current uk
recommendation of 400
international units is probably not
going to increase your serum levels much
at all
to be honest most multivitamins contain
this amount and hoping that this will
raise serum vitamin d levels is like
hoping to put out a forest fire by
peeing on it
you can try but you won't get very far
that's why higher doses of vitamin d3
may be better up as far as the upper
recommended dosage of 4
000 international units in fact if you
get a blood test and your serum vitamin
d levels are very low
your doctor may even prescribe you an
even higher dose vitamin d supplement
until your serum levels increase like i
said the best way to know your vitamin d
level is to get tested
in the meantime supplementing with a
daily dose as much as the upper uk limit
of 4 000 international units of d3
may be enough to help prevent
insufficiency so what do you think
did that clear things up for you about
vitamin d as always if you have any
questions let me know in the comments
below and remember to like and subscribe
to my protein youtube channel
for more great evidence-based
information
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