The
Different Forms of Vitamin E
The Different Forms of Vitamin E
By: Dr. George Obikoya
Vitamin E is a fat-soluble antioxidant vitamin
that helps to neutralize potentially damaging free radicals in our
body. It exists in eight different forms, alpha-tocopherol being
the most active form of vitamin E in humans and a powerful biological
antioxidant. The natural, and preferred form to take is d (not dl)
alpha tocopherol.
Each form has its own biological activity, the measure of potency
or functional use in the body. The tocopherol and tocotrienol subfamilies
are each composed of alpha, beta, gamma and delta vitamins having
unique biological effects.
Vitamin E is thought to help in some skin conditions, male infertility,
heart disease prevention, Alzheimer's disease, type 1 diabetes,
circulatory problems, arthritis, premenstrual symptoms, and aging.
It is also used as an antioxidant and to enhance immune system functioning
in the elderly.
The tocopherols are a closely related group of biologically active
compounds that vary only in number and position of methyl groups
in the molecule; however, these structural differences influence
the biological activity of the various molecules. (In other words,
each type of vitamin e is similar, but work in slightly different
ways).
The active tocopherols are named in order of their potency. Thus
alpha-tocopherol is the most active. Some metabolites of alpha-tocopherol,
for example, alpha-tocopherolquinone, and alphatocopheronolactone
have activity in some mammals such as rats and rabbits although
not in humans and these metabolites do not support all the functions
attributed to vitamin E. In other words, stick with the tocopherols.
The vitamin E group also is necessary for normal mammal (including
human) growth; without these tocopherols, our fertility is compromised
and we may have children that develop abnormalities of the central
nervous system, muscles, and organs, especially the liver.
Most of the stored vitamin E is found in body fat, although large
amounts also occur in the uterus of females and the testis of males.
The various forms of vitamin E are stored in tissues in different
amounts; alpha-tocopherol is stored in higher concentrations than
the other forms.
Many people don’t know that there are several different forms of
vitamin E. Why is this important to know? The different forms of
vitamin E are truly disctinct and have different levels of effectiveness.
Each form functions differently in the body and only one form truly
represents natural vitamin E - the d-alpha-tocopoheryl form.
There are several distinct forms of vitamin E in dietary supplements
vying for your attention. While tocotrienols, the form of vitamin
E that features an unsaturated side chain, is becoming more popular,
tocopherols (mainly alpha-tocopherol) still remain the most widely
used and researched form. Tocopherol supplements usually feature
either alpha-tocopherol, alpha-tocopheryl acetate or alpha-tocopheryl
succinate, the latter two thought to confer enhanced stability.
You can get Vitamin E in synthetic form as dl-alpha tocopheryl.
This is the cheapest and least effective form of vitamin E. The
chemically produced dl-alpha-tocopher(y)l acetate or succinate,
identified by the letter "l" after "d", was
originally used as the industry standard for research. This was
because it showed higher blood levels than the natural forms, alpha,
beta, gamma and delta tocopherols, spelled with an "o"
instead of a "y" to identify them as natural forms. Alpha-tocopherol
can be derived from natural sources or can be synthetically produced.
Natural-source alpha-tocopherol is a single stereoisomer and is
also designated by the prefix "RRR." The synthetic form
is a mixture of eight stereoisomers identified by the prefix "dl-"
or "all-rac."
Natural-source d-alpha-tocopherol (as opposed to dl) has been shown
to have a higher biopotency than the dl-rac form. The currently
accepted ratio is 1.36:1 (d:dl). A recent proposal has been made
to the National Academy of Sciences to change this biopotency factor
to 2:1 based on the results of more recent research studies. But
some researchers challenge this idea believing it is based on incomplete
conclusions extrapolated from the studies.1
The fact that Vitamin E works at the mitochondrial rather than cellular
level, and does not work at the blood level is proof that synthetic
Vitamin E is an ineffective form. Furthermore, diabetics usually
show high blood levels of Vitamin E because their heavily sclerosed
circulatory system does not permit synthetic Vitamin E to reach
the mitochondria level. Indeed, only natural form vitamin E has
been discovered in brain tissue. Synthetic Vitamin E also causes
side effects including heart palpitations even at relatively low
dosage.
Esterified vitamin E is d-alpha tocopheryl. Originally alpha-tocopherol
was erroneously thought to be the only active factor of the Vitamin
E group: alpha, beta, delta, and gamma. We now know better. Alpha,
beta, gamma, delta tocopherol, can all be esterified (converted)
into a single acid ester.
However, esterified vitamin E is very resistant to destruction by
oxidation even in the presence of minerals or at high temperatures
but this destroys its antioxidant properties, although not its ability
to prevent clot formation in our blood vessels. Mixed Tocopherols
or d-alpha tocopherol are recommended for both vitamin E’s antioxidant
and anti-thrombotic effects.
A good multivitamin is the foundation of health
and nutrition. Take a look at our scientific reviews of many of
the popular brands for factors such as ingredients, areas of improvement,
quality level, and overall value. If you are looking for a high
quality liquid multivitamin, we suggest that you take a look at
the Multivitamin
Product Comparisons.
References
1. Hoppe PP, Krennrich G. Bioavailability and potency of natural-source
and all-racemic a-tocopherol in the human: a dispute. Euro J of
Nutr 2000;39:183-93.
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