Hi. I'm Dr. Chris Masterjohn of
ChrisMasterjohnPhD.Com and you're
watching Masterclass With Masterjohn.
This is the fourth in a series of videos
on the antioxidant defense system and
today we are for the first time looking
at a specific component of that system in
detail and we're starting with vitamin E.
You can see the structure of vitamin E
on the screen and what's shown is alpha-tocopherol.
Vitamin E actually comes
in eight forms and it can be split between
tocopherols and tocotrienols. Within
each of those we have four subforms:
alpha, beta, gamma, and delta. If you see
that there's a ring structure on the
left and a tail structure on the right
the tail structure of all the tocopherols
is the same and it differs from the
tail structure of tocotrienols in
that tocopherols have a saturated tail
and tocotrienols have double bonds in
this tail that makes it unsaturated. The
difference between alpha, beta, gamma, and delta
is in the ring structure.
Alpha-tocopherol has three methyl groups in the
ring structure. All of the other tocopherols
have fewer than that, and they
differ based on the number and position
of those methyl groups. If you were to
compare alpha-tocopherol to gamma-tocopherol
that difference in
methyl groups would be what you
see different between them. But if you
compare alpha-tocopherol to
alpha-tocotrienol, the ring structure will be
exactly the same and it will be the tail
structure that differs. The name "tocopherol"
comes from the Greek "tokos"
meeting "birthgiving ," "fero" "to carry,"
and the suffix "-ol," which means it's an
alcohol. In chemistry, anything that has a
hydroxyl group, OH, is an alcohol and
so the name tocopherol means an
alcohol that helps a mother carry a
pregnancy to term and give birth. And
that's because when we first discovered
vitamin E deficiency it was associated with
infertility. now tocotrienol is a
later name where "triene" means three
double bonds and that refers to the
number of double bonds that are in the
tail and that's where that name comes from.
Although vitamin E was originally
known as the fertility vitamin, we now
know from its chemistry that its
function is to convert lipid peroxyl
radicals to lipid peroxides and thereby
avert lipid peroxidation chain
reactions in cellular membranes.
This is the only well-established role
as a direct antioxidant in this context.
There are a lot of other things that we
believe vitamin E does, like
regulate gene expression, but it's not
clear if it does them independently from
this process because oxidation and lipid
peroxidation affects many other cellular
processes. So to date there's no real
clear evidence that vitamin E does
anything that can't be traced directly
to its role as an antioxidant in this
context. And so we can look at the
infertility that originally came with
vitamin E deficiency and we can say that
was due to lipid peroxidation. Similarly, we
could say lipid peroxidation is believed
to play a role in many other chronic
degenerative diseases that are more
common today and so wherever you see
oxidative stress and lipid peroxidation
there's good reason to think vitamin E
may be protective. Because vitamin E's
role is to protect PUFAs, then you
can see in the food supply foods that have
more PUFA in them will tend to have
more vitamin E. But it doesn't all come
in the same ratio, and the ratio of
vitamin E to PUFA in the diet may be more
important than the amount of vitamin E
itself. If you look at the RDA for vitamin E,
for most adults, it's 15 milligrams per
day, but that can vary with lactation and
pregnancy and it can vary with age. We
see that the RDA takes into contextual
factors sex, age, pregnancy, and lactation
but not PUFA intake. That can be misleading
because if you look at the actual DRI
report you can see that they clearly
believed
that vitamin E requirements depend
on PUFA intake. This is a direct quote from
the report that underlies the current
RDA for vitamin E. "Vitamin E requirements
"have been reported to increase when
"intakes of polyunsaturated fatty acids (PUFAs)
"are increased. Based on these data it
"was suggested that a ratio of at least
"0.4 milligrams alpha-tocopherol
"per gram of PUFA should be consumed. However, the
"method of determining the vitamin E
"requirement generated by PUFA intake is
"not universally accepted because the
"amount of vitamin E required to
"stabilize PUFAs in tissues is
"influenced to a greater extent by their
"degree of unsaturation than by their mass."
What that means is that you can consume
linoleic acid from vegetable oil that has
two double bonds, but you can also
consume EPA from fish oil that has
five double bonds or DHA from fish oil
that has six double bonds. EPA and DHA are
more vulnerable to peroxidation than
linoleic acid because they have more
double bonds.
"Moreover PUFAs are not deposited in
"the tissues in the same proportions that
"they occur in the diet." In other words
you eat a given amount of PUFA but
it's not the amount you eat, it's the
amount that winds up in membranes that
actually makes you need more vitamin E.
One is influenced by the other but it's not
the same as the other. They go on, "Finally,
"dietary PUFAs are modified by elongation
and desaturation . . . " That means you can eat
linoleic acid but then you can make
it longer and introduce more double
bonds and turn it into something like
arachidonic acid, which is more
vulnerable to peroxidation, or you can
consume something like alpha-linolenic acid
and convert it, from flax oil, and
convert it to EPA or DHA, which is longer
and has more double bonds and it's more
vulnerable to peroxidation. They go on, ". . . and
"are catabolized to various degrees
depending on energy status." That means if
you're in a caloric deficit you're going
to burn PUFAs for energy and so they're
not going to influence your
vitamin E requirement but if you're in a
caloric excess you're going to store them
in your membranes more often or in your
adipose tissue and that is going to
influence your vitamin E requirement.
They conclude, "Although it is clear that
"the relationship between dietary vitamin E
"need is not simple, high PUFA intakes
"should certainly be accompanied by
increased vitamin E intakes." How often
do you see scientists say "certainly"? Not very
often. So this is really important
because if you just look at the RDA
itself PUFA is nowhere to be seen, but if
you read the report they state clearly
that the reason they didn't express the
RDA per gram PUFA is because there's no
straightforward mathematical calculation
to express it in that way, but the
principle that the more PUFA you eat
the more vitamin E you need is solid, so
solid they call it "certain." Now that's
really important because if you look at
how vitamin E is distributed in foods
you get a very different picture if you
express it per gram PUFA than if you
express it
total amount in the food. The data that's
on the screen, I used alpha and
gamma tocopherol because these are the
major forms of vitamin E that are
important, but you'd get similar results if
you just looked at alpha tocopherol or
if you took total vitamin E.
What you see is that when you only look
at the amount of vitamin E in the food
wheat germ oil looks way better than
everything else. Corn oil is pretty hot
itself, palm oil is pretty good, but not
as good as corn oil, butter's terrible, olive
oil's kind of "eh." But if you express that per gram PUFA
what you see is that all the sudden
palm oil is the best, butter is still not as
good as olive oil but the difference is
isn't as big, and wheat germ oil no longer takes
the lead.
Well, when we're looking at something
like butter
we also have to take into account what
was the cow eating? And when cows eat grass,
which is high in photosynthetic activity,
they wind up with more vitamin E in their
meat and their butter when when they eat grain.
So let's take a look at what's happening
in photosynthesis to
see why that's the case. In
photosynthesis, we take energy from
sunlight and we combine hydrogen from
water with carbon and oxygen from carbon
dioxide and that makes sugar. There's
some oxygen left over and that gets
released into the atmosphere but oxygen
in high concentrations, especially in the
presence of ultraviolet light from the
sunlight, can be converted into reactive
oxygen species like superoxide and
hydrogen peroxide. The plant requires
vitamin E to protect its PUFAs from the
reactive oxygen species just like we do.
So a plant that has high photosynthetic
activity needs a lot of vitamin E to
protect against that oxidative liability
from oxygen and the ultraviolet light. So
if we add corn as representative of
grains and lettuce as representative of
greens to our chart, we see that they're
meaningless if you look at total vitamin E.
But if you look at vitamin E per
gram PUFA, lettuce as a leafy green
comes out way ahead of most other things
on this list, even ahead of palm oil. Now for
humans,
we're not going to eat lettuce as most of
our calories so that's not that
important for directly eating it, but when we
think about the animal products we use, a
cow can eat most of its calories as grass
and so if the cow is eating grass instead
of eating grain, the cow's going to get a
lot more vitamin E in its diet, and
that's because this grass is heavily
photosynthesizing so its PUFAs are very
vulnerable,
whereas the grain not only is it not
photosynthesizing but it's metabolically
dormant so there's very little risk of
PUFAs getting harmed by reactive
oxygen species. If you look across
studies at the vitamin E contents of
grass-fed and grain-fed beef, you see
grass-fed always comes out on top.
Whether it's four versus less than 1, 3
versus 1.5, 2 versus less than 1, and so on
grass-fed beef is generally 1.3-5.4-fold
higher in vitamin E than grain-fed beef.
Similar results you'd get from butter, and that
reflects the fact that cows that eat grass are
eating photosynthetic tissues that need a
lot of vitamin E and therefore contain
a lot of vitamin E and provide a lot
of vitamin E to the cow. If we add into our
list of fats and oils grass-fed butter
then it comes out a little bit better
than olive oil, way better than butter
from cows fed hay, or average
butter that you find in the supermarket
and although it's not as good as palm
oil it's better than corn oil. and it's
pretty competitive with wheat germ oil.
So the vitamin E to PUFA ratio matters a lot
and the method of production matters.
If we look at how vitamin E is digested
absorbed and transported, it has some
implications for our diet.
Let's take absorption first. If this
cylinder is the small intestine, we eat
vitamin E and it's incorporated with bile
acids and pancreatic enzymes into what
we call the mixed micelle. That then is
absorbed into the intestinal cell and
repackaged. Now what is stimulating the
production of the mixed micelle and the
bile acids and the pancreatic enzymes is
primarily the fat in our diet. If you
think about the amount of fat we eat in a meal,
it's measured in grams. You think about
the amount of vitamin E we eat in a meal,
it's measured in milligrams. So there's way more stimulus
from the fat to stimulate the
fat-digestion machinery than there is from the
vitamin E, and so that fat says to our
bodies, "make more bile acids, make more
"pancreatic fat-digesting enzymes, create
"more machinery to make the mixed micelle."
That helps us absorb vitamin E. What you see
on the screen is data from a study where
subjects were given either a fat-free
meal, a low-fat meal, or a full-fat meal.
and they tested how much vitamin E did
they absorb. The fat-free meal was just an
apple with a vitamin E supplement, the low-fat
meal was the same thing plus
a bagel with low-fat cream cheese
and the full-fat meal was the same thing
only the cream cheese was full-fat instead
of low-fat. The high-fat meal wasn't
really that high in fat, it was 21% of
calories,
but it was a lot higher than the low-fat
meal, which was six percent of calories.
On the left you can see that they absorbed
10% of vitamin E when it was in a fat-free
meal, twenty percent with the low-fat
meal, and 33 percent with the high-fat
meal, so by bringing fat from 0 to 6 to 21
percent of calories you get this
graded increase and you triple your
absorption of vitamin E by including the
full-fat cream cheese. Now maybe if they
had eaten thirty or forty percent of
their calories they would have absorbed
even more but the principle here is the
more fat you eat the greater proportion of
vitamin E you're going to absorb from the
diet. If you're just eating natural foods I
would say that means eat some fat, you
don't have to eat a really high-fat diet but
you should have some fat in your diet
to make sure you're absorbing your
vitamin E. If you're going to take a vitamin
E supplement, you should take it with
the largest meal of the day, and if your
fat varies a lot between different meals
you should take it with the meal that has the
greatest amount of total fat to maximize
its absorption. Now if we come back to
this slide we see that after vitamin E
is absorbed it gets repackaged in
intestinal cells into chylomicrons. Those
go into the lymph and then into the
blood and when they go into the blood
they can be taken up by peripheral
tissues, meaning tissues other than the
liver in this case, where the vitamin E
can be exchanged with other lipoproteins
like LDL and HDL, but most of it is
going to get taken up by the liver. Now
the liver has a protein called alpha-tocopherol transfer protein
or alpha-TTP that
recirculates the vitamin E into VLDL
particles that go back into the blood.
That VLDL can deliver alpha-tocopherol
or other forms of vitamin E to the
peripheral tissues again and eventually
it's digested into LDL. And this first uptake
by peripheral tissues from the chylomicrons
is relatively minor compared to the
amount of vitamin E that's taken up
by VLDL and LDL in the time after the
vitamin E has gone through the liver and
recirculated with alpha-TTP. Now this is
important because there's a rare genetic
defect in alpha-TTP that makes it really
hard to get enough vitamin E from a natural
diet pretty much impossible so you have to
supplement really high doses of vitamin E to
overcome it and it also makes it really
hard to get that vitamin E into the brain
because alpha-TTP also plays a role in
getting vitamin E into the brain.
But for people who don't have any
genetic defects alpha-TTP also makes it, has
some important implications for how we
think about what we want to eat.
for vitamin E. The data on the screen
shows the affinity of alpha-TTP for the
different forms of vitamin E. Alpha-tocopherol
is arbitrarily set at a hundred
percent and everything else is expressed
as a percent affinity compared to alpha-tocopherol.
As you go from alpha to beta to
gamma tocopherol, you go from a hundred to
38% to 9%. So alpha-tocopherol
has ten
times more affinity for alpha-TTP than gamma-tocopherol.
If you go from tocopherol to
tocotrienol, again alpha-tocopherol
has ten times more affinity than alpha-tocotrienol
so alpha-tocopherol
is overwhelming recirculated in
preference to all the other forms. If we
look at standard diets,
most people are consuming more gamma
tocopherol than alpha-tocopherol, but once
it goes to their liver alpha-TTP
recirculates a lot more alpha-tocopherol
than gamma-tocopherol, and so in the blood
of people eating a standard diet
there's a lot more alpha-tocopherol
than gamma-tocopherol. The alternative to
recirculation by alpha-TTP is enzymatic
degradation to metabolites that are
excreted in the urine. So if you look at
people on a standard diet they have far more
gamma-tocopherol metabolites in their urine
than they do alpha-tocopherol
metabolites.
Well why does it seem that our bodies
are trying to concentrate alpha-tocopherol?
What you see on the screen is a comparison
of the structures of alpha and gamma.
Alpha is on the top and gamma's on the bottom.
Alpha-tocopherol has three methyl groups
whereas gamma tocopherol only has two and in
place of the third it just says a
hydrogen. That makes alpha-tocopherol a
much better antioxidant because when
alpha-tocopherol donates an electron it
needs to stay stable until it can reach
vitamin C to be recycled. When it donates an
electron it is now a free radical and so
it's in great danger of pairing up that
electron before it gets to vitamin C. So
what it does is it passes the unpaired
electron from one methyl group to the
next like a hot potato and that
circulation of the unpaired electron
from one to the next to the next to the
next is something called resonance
that is a chemistry term. If you look
at gamma tocopherol it only has
two methyl groups, so it will pass back
and forth the unpaired electron like a
hot potato but it can't keep it stable
anywhere near as well as alpha-tocopherol can
because it only has this small space of the ring
that can engage in this resonance
instead of this large space fully around the ring.
So alpha-tocopherol is preferentially
recirculated, probably because it is a
much better antioxidant than the other
forms.
However, you could make a case that gamma
tocopherol may have unique roles that
alpha tocopherol doesn't have. When we
look at superoxide, one of the things
that it can do is react with nitric oxide
to form for peroxynitrite and peroxynitrite
is a very dangerous reactive
nitrogen species because gamma-tocopherol
does not have a methyl group here
it can accept nitrogen where
alpha-tocopherol can't.
and gamma-tocopherol can scavenge peroxynitrite
to form a stable product known
as nitro-gamma-tocopherol or NGT. So it may be
the case that gamma-tocopherol plays a
unique role in scavenging reactive
nitrogen species. To date, we don't really
know that gamma tocopherol is uniquely
important, but we do know that natural
diets would always lead to circulating
gamma-tocopherol in the blood and natural
diets would always contain a mix of
different tocopherols and tocotrienols.
If you consume an alpha-tocopoherol
supplement that instead of providing 10
or 15 or 20 milligrams, like you could
maybe get from food, provides 100, 200
300, or 400 milligrams, then alpha-tocopherol
goes into the liver, is ten times
more likely to be
recirculated into the blood, and if you
have ten times more alpha-tocopherol than
other forms of vitamin E, you're gonna wash
out alpha-TTP. Alpha-TTP is going to be
flooded by nothing but this
alpha-tocopherol that has such a high
affinity for it and you're going to drown
out the other forms of vitamin E like gamma-tocopherol
in the blood. And vitamin E
supplementation with alpha-tocopherol has been shown
to cut gamma tocopherol levels by
large amounts. So what that means is that
it's wise that if you're going to take a
vitamin E supplement, it should contain
some gamma-tocopherol and some of the
other forms of vitamin E. My personal
preference is to use things like
grass-fed butter and palm oil. Palm oil is
rich in the full spectrum of tocopherols
and tocotrienols, so I think it makes
more sense to use moderate doses of the
full spectrum of vitamin E forms than to
use high doses of just alpha-tocopherol
but that doesn't change
the fact that our bodies really seem
hardwired to preferentially recirculate
alpha-tocopherol
and we know from chemistry that alpha-tocopherol
is the most superior
antioxidant out of all forms of vitamin E.
So let's not megadose with alpha-tocopherol
and drown out all the other forms, but
let's also not lose sight of the fact
that alpha-tocopherol is super important
and there's more evidence behind
it's importance than there is for any of the
other forms of vitamin E. So what we
wouldn't want to do is try to develop a
supplement that just has gamma-tocopherol in it,
or that only emphasizes
these other forms of vitamin E
without including alpha-tocopherol, which
we know to be important.
All right, so to sum up, when you're
looking at foods the vitamin E to PUFA
ratio is a better index of how good a
food is as a source of vitamin E than
only looking at the amount of vitamin E
in that food. When you eat vitamin E you need to
eat it with fat to absorb it, and it's better
to get a full spectrum of natural forms
of vitamin E than to megadose with only alpha-tocopherol
because it could drown out the
other forms.
So this was vitamin E, next time is
vitamin C, and we'll continue to take
apart each part of the antioxidant
defense system as we move along.
Signing off this is Chris Masterjohn of
ChrisMasterjohnPhD.Com, and
you've been watching Masterclass With Masterjohn,
and i'll see you in the next
video.
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