of vitamin E deficiency often take years to develop in
adults; the results are seen much sooner in children.
Almost all healthy people living in the developed
world get enough vitamin E through diet to prevent
symptoms of vitamin E deficiency from developing.
There is some debate, however, about the frequency
with which deficiencies exist that do not produce
obvious symptoms (subclinical deficiencies). Those at
greatest risk for vitamin E deficiency include:
severely premature infants who weigh less that 3 lb
4 oz (1,500 g) at birth
people with gastrointestinal diseases such as Crohn’s
disease, cystic fibrosis, or inflammatory bowel dis-
ease that interfere with the absorption of fat from the
intestine
people who have had part of their stomach or intes-
tine surgically removed for weight loss or other
reasons
people eating very low fat diets for an extended time
people with anorexia nervosa (self-starvation)
people with the rare inherited disorders abetalipo-
proteinemia and ataxia and vitamin E deficiency
(AVED), both of which prevent normal use of vita-
min E
Controversy about vitamin E centers on its use as a
dietary supplement to help prevent or treat disease.
Many health claims are based on the antioxidant prop-
erties of vitamin E. Initially, it appeared that large doses
of vitamin E could help prevent heart disease and some
cancers. Then in 2004, researchers at the Johns Hopkins
University School of Medicine re-analyzed the data (a
meta-analysis) from 19 major clinical trials that
included more than 136,000 individuals. They found
that taking 400 IU or more of vitamin E daily increased
a person’s risk of death by about 4%. However, some
experts have questioned the validity of the Johns Hop-
kins analysis. The role of vitamin E is further compli-
cated by the fact that it comes in many forms, and
researchers are not completely clear on what, if any,
roles the different forms play in maintaining human
health. Clinical trials are currently underway to deter-
mine safety and effectiveness of vitamin E in a variety of
situations. Individuals interested in participating in a
clinical trial at no charge can find a list of open trials at
http://www.clinicaltrials.gov.
CARDIOVASCULAR DISEASE.Since the 1940s,
researchers have suggested that vitamin E might pro-
tect against heart disease. This theory is based on its
activity as an antioxidant. Because vitamin E oxidizes
(neutralizes) LDL or ‘‘bad’’ cholesterol, researchers
have suggested that large doses of vitamin E may
slow or prevent the build-up of material on the walls
of arteries and thus help prevent cardiovascular
disease.
Results of studies testing this idea are mixed. Sev-
eral large studies followed healthy people who took
vitamin E and looked for a correlation between the
amount of vitamin E in their diet and whether they
were diagnosed with heart disease or died of a heart
attack. Two studies found that people who got least
7 mg of alpha-tocopherol daily from food were about
one-third less likely to die from heart disease than
those people who consumed 5 mg of less of alpha-
tocopherol. On the other hand, another large, well-
designed study (the Heart Outcomes Prevention Eval-
uation) found no cardiovascular benefit to large doses
of vitamin E. A well-controlled study (the CHAOS
study) done in Great Britain found that when people
who already had heart disease were given large doses
(400 IU or 800 IU) of Vitamin E, the rate of non-fatal
heart attacks dropped dramatically, but that the over-
all death rate from heart disease did not change.
The official position of the American Heart Asso-
ciation published in its ‘‘Diet and Lifestyle Recom-
mendations Revision 2006’’ is that ‘‘Antioxidant
supplements have not been shown to be helpful in
preventing heart disease and are not recommended in
these guidelines.’’ The recommendations specifically
mention the possibility of ‘‘an increased risk of heart
failure and the possibility of increased total mortality
(death) from high dose vitamin E supplements.’’ More
research needs to be done in this area.
CANCER.The antioxidant activities of vitamin E
are also thought to help protect against the develop-
ment of cancer by removing free radicals that damage
cell membranes and DNA. Vitamin E is also believed
to neutralize nitrosamines. Nitrosamines are known
carcinogens found in tobacco and smoked meats.
Much of the evidence for the action of vitamin E on
cancer comes from animal studies. The results of
human studies are inconclusive and often confusing.
According to the American Cancer Society, there is
some evidence that vitamin E may have a protective
effect against coon, rectal, bladder, andprostatecan-
cer, but not other cancers. There is no evidence that
vitamin E slows the growth of cancer once it has
already developed, and some conflicting evidence
about whether it interferes with the effectiveness of
chemotherapy and radiation therapy. Research on
the relationship of vitamin E and cancer continues.
CATARACTS.Cataracts form on the lens of the eye,
making it cloudy and reducing vision. They are
thought to form because proteins in the lens are oxi-
dized. Ten studies have been done to see if theVitamin E