The real facts about the vitamin E death warning...
Do you ever feel fed up with all the conflicting health information
in newspapers and magazines?
This week, you'll see a story about the benefits of taking a certain
supplement. A week later, you'll read or hear a report about the
dangers of the very same substance, with warnings by an expert to
stay away from it.
A good example comes from the latest
"death warning" about vitamin E. According to recent
headlines, people could be "risking their lives" if they
take even moderately high doses of vitamin E [1].
To add to the confusion, researchers from Israel now tell us that
some patients with diabetes can reduce their risk of dying
from heart disease by taking — you guessed it — high doses
of vitamin E [2].
Don't throw your vitamin E supplements in the bin just yet. There
are several important aspects of the Johns Hopkins study that didn't
get much coverage in the news.
Here's a closer look at what they actually did.
The researchers looked at a number of studies carried out between
1993 and 2004. All compared vitamin use against a dummy supplement
(placebo).
They found that the risk of death did not differ significantly
between people given vitamin E and those assigned to placebo.
However, the effect of vitamin E differed according to how much
was used. In the low-dose studies, vitamin E was linked with a small
reduction in the death rate.
In the high-dose studies, those who took vitamin E had a 4% increase
in the risk of death. Though this increase was small, it was statistically
significant.
It was this discovery that generated the headlines.
One problem is that the review included studies where vitamin E
was taken with other vitamins and minerals. The increased risk of
death found in some of the studies could have been linked with these
other nutrients. It may have had nothing to do with vitamin E.
What's more, many of the study groups were people with pre-existing
chronic diseases such as cancer, heart disease, Alzheimer's, Parkinson's
and kidney failure.
Even the editors of the Annals of Internal Medicine (the
journal where the study was published) write that the findings may
not apply to healthy adults.
Dr. Alan Gaby, an expert in nutritional therapies, also points
out that some of the results were complicated by the fact that the
vitamin E and placebo groups were not comparable.
"In one high-dose vitamin E study (Cambridge Heart Antioxidant
Study), the vitamin E group had higher cholesterol levels and significantly
greater percentages of participants with high blood pressure, diabetes,
cigarette smoking, and severe coronary artery disease, compared
with the placebo group," says Dr. Gaby.
"Thus, the people taking vitamin E were sicker than those
taking the placebo, a fact that could account for the slight increase
in mortality seen in the vitamin E group."
There are also several
different forms of vitamin E. Read the label on a vitamin E
supplement, and it will probably say alpha-tocopherol (pronounced
al-fa tocko-ferol).
Most of the studies reviewed in the Johns Hopkins research were
done using the synthetic (dl-alpha-tocopherol) rather than the natural
(d-alpha-tocopherol) form of alpha-tocopherol.
Natural vitamin E has roughly twice the availability of synthetic
vitamin E. Because of this, you have to take about twice as much
of it to get the same effect [4].
If there is a small negative effect of high-dose vitamin E, it
might be due in part to the use of dl-alpha-tocopherol.
Vitamin E is actually a collective term for eight naturally occurring
compounds, four tocopherols (alpha-, beta-, gamma- and delta-) and
four tocotrienols (alpha-, beta-, gamma- and delta-).
Concentrations of alpha-tocopherol are higher in wheat germ oil,
almond and sunflower oil; gamma-tocopherol is the major form of
vitamin E in corn oil and soybean oil; levels of tocotrienols are
high in rice bran, barley, oats and palm oil.
Although most research has focused on the potential health effects
of alpha-tocopherol, the three other tocopherols and four tocotrienols
are also important.
In fact, supplementing with alpha-tocopherol has been shown to
reduce blood levels of gamma- and delta-tocopherol [3].
Although they're usually more expensive than alpha-tocopherol,
mixed tocopherols are the preferable form of vitamin E, in terms
of both safety and effectiveness.
If you do use a high-dose vitamin E supplement, look for one that
contains mixed tocopherols. Some manufacturers use this term to
mean the synthetic dl-alpha-tocopherol, so you need to read the
label closely.
Of course, the fact that some forms of vitamin E are natural doesn't
mean it can be consumed safely in unlimited amounts. Many supplements,
including vitamin
C, iron, CLA and CoQ10 —
under certain conditions — can have negative side effects. Even plain
water has the potential to be harmful [6].
Based on its blood-thinning effects, there are concerns
that vitamin E could cause problems if combined with medications
that also thin the blood, such as aspirin. In theory, the blood
could thin too much, causing bleeding problems.
Vitamin E may also enhance the body's sensitivity to its own insulin
in people with type II diabetes [5]. This could lead to a risk of
blood sugar levels falling too low. If you're taking medication, it would be a good idea to talk with
your physician before using a high-dose vitamin E supplement.
Related Articles
References
1. Miller, E.R. 3rd, Pastor-Barriuso, R., Dalal, D., Riemersma,
R.A., Appel, L.J., & Guallar, E. (2004). Meta-Analysis: High-Dosage
Vitamin E Supplementation May Increase All-Cause Mortality. Annals
of Internal Medicine, 142
2. Levy, A.P., Gerstein, H.C., Miller-Lotan, R., Ratner, R., McQueen,
M., Lonn, E., & Pogue, J. (2004). The effect of vitamin E supplementation
on cardiovascular risk in diabetic individuals with different haptoglobin
phenotypes. Diabetes
Care, 27, 2767
3. Huang, H.Y., & Appel, LJ. (2003). Supplementation of diets
with alpha-tocopherol reduces serum concentrations of gamma- and
delta-tocopherol in humans. Journal
of Nutrition, 133, 3137-3140
4. Burton, G.W., Traber, M.G., Acuff, R.V., Walters, D.N., Kayden,
H., Hughes, L.,& Ingold, K.U. (1998). Human plasma and tissue
alpha-tocopherol concentrations in response to supplementation with
deuterated natural and synthetic vitamin E. American
Journal of Clinical Nutrition, 67, 669-684
5. Manning, P.J., Sutherland, W.H., Walker, R.J., Williams, S.M.,
De Jong, S.A., Ryalls, A.R., & Berry, E.A. (2004). Effect of
high-dose vitamin E on insulin resistance and associated parameters
in overweight subjects. Diabetes
Care, 27, 2166-2171
6. Noakes, T.D. (2003). Overconsumption of fluids by athletes. British
Medical Journal, 327, 113-114
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