Synthetic vs.
Natural Vitamin E
(An interview with Robert V. Acuff,
Ph.D. by Nature's Impact magazine)
NI: Can you explain
more about the chemical difference
between natural and synthetic vitamin
E?
RA: For consumers, it
can be a little tricky to find authentic
natural vitamin E in a supplement.
People have to find "d-alpha tocopherol" in
the list of ingredients on bottles
of vitamin E. Some brands confuse consumers
by suggesting that they're buying natural
vitamin E when they're actually buying
the synthetic form.
Let's start with some
basics. There are eight naturally occurring
compounds with vitamin E activity.
These are closely related molecules.
Four are tocopherols and four are tocotrienols.
The form with the greatest biological
activity in people is unquestionably
the alpha tocopherol form. The others
play minor roles in human health.
When you buy a natural
vitamin E supplement, the d-alpha form,
you are getting a single chemical structure. Synthetic
vitamin E has a different chemical
structure and, in fact, actually
consists of eight different stereoisomers
of alpha tocopherol. The problem is
that only 12.5 percent of synthetic
vitamin E is the same as natural vitamin
E; the other seven stereoisomers have
lower activities in the body. Isomers
are molecules with the same atoms,
but in a different arrangement. The
arrangement of atoms influences the
properties and the biological activity
of a substance.
Nl: Can you explain
the difference in how natural and
synthetic vitamin E are absorbed
and retained in the body?
RA: It's a very important
difference, and there's some interesting
history leading up to my research and
that of my colleagues. Historically,
researchers have believed that natural
vitamin E in the acetate form, milligram
for milligram, is 1.36 times (or 36%)
more biologically active than the synthetic
form.
However, you may know
that virtually all the vitamin E supplements
sold on the market are measured in
international units (IU), not milligrams
(mg). The IU standard was developed
as a way of leveling the playing field
between synthetic and natural vitamin
E. So while natural vitamin E per milligram
is more potent, the theory was that
natural and synthetic vitamin E in
IU should be equal.
Nl: Why do you believe
natural vitamin E is absorbed better
than synthetic?
RA: There has been some
excellent research in this area by
Maret Traber, Ph.D., of Oregon State
University, and Angelo Azzi, Ph.D.,
of the University of Bern, Switzerland.
Vitamin E doesn't just float through
the blood by itself. The transport
of vitamin E through the body depends
on a protein called tocopherol-binding
protein, which is produced in the liver.
After you consume vitamin E, it moves
from the digestive tract to the liver,
which is the body's chemical processing
plant. It's in the liver that tocopherol-binding
protein hooks up specifically with
the natural d-alpha tocopherol form
of vitamin E instead of other natural
forms and synthetic vitamin E. The
fact that tocopherol-binding protein
prefers the natural d-alpha tocopherol
indicates that this is the form of
the vitamin the body principally uses.
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