This was gotten from Harvard Health
Easy does it with
vitamin E
Published: March, 2014
Swallowing
an amber-colored vitamin E capsule has long been a daily ritual for millions of
American women. It may be time to stop.
Today
vitamin E is one of the most widely used supplements, taken regularly by nearly
a quarter of adults ages 55 and over. Its popularity derives from studies over
the years suggesting that vitamin E's antioxidant properties could help stave
off common age-related ills, such as heart disease, cancer, and cataracts. Many
health care professionals were personally on board, taking the supplement as
well as recommending it. Although there was no proof of its effectiveness, the
consensus was, "It might help, and it couldn't hurt."
But analysis
suggests that vitamin E supplementation might not be as harmless as everyone
was assuming. Researchers pooled and examined the results of 19 clinical trials
published between 1966 and 2004 involving nearly 136,000 people who took
vitamin E for one reason or another. They found that the overall risk of dying
was greater for people who took 400 IU (the amount found in a typical vitamin E
capsule) or more daily, compared to those who took lower doses (Annals of
Internal Medicine, Jan. 4, 2005). And the risk of dying rose with
increasing doses above 150 IU per day.
This study
does have some drawbacks. In the 19 trials it analyzed, people using doses of
400 IU or more were largely older adults with chronic diseases. So the findings
don't necessarily apply to younger, healthy adults. Also, in 10 of the 19
trials, people took other nutritional supplements as well, making it hard to
single out vitamin E as the sole culprit. Finally, the amount of increased risk
was very small. And in those taking doses of 150 IU per day or less, the risk
of death from all causes was actually lower. Thus, some experts
aren't convinced there's any increased risk, despite what was found in this
study.
Nevertheless,
the research confirmed a trend in expert opinion. This once-lauded vitamin has
been losing its luster among nutrition experts for some time. Until 2003, for
example, students who took the "Preventive Medicine and Nutrition"
course at Harvard Medical School were assigned to argue the wisdom of
recommending vitamin E to patients. "But we dropped vitamin E as a debate
topic," says HWHW advisory board member Dr. Helen
Delichatsios, because recent data overwhelmingly show that vitamin E is not
useful. What happened, and what does it mean for you? First, some background.
The many faces of vitamin E
Vitamin E
occurs in eight different forms. Those most commonly found in foods and
supplements are d-alpha-tocopherol — the synthetic form is d,l-alpha-tocopherol
— and gamma-tocopherol. Synthetic alpha-tocopherol is only half as active in
the body as the natural form. Certain supplements, labeled "mixed
tocopherols," contain various other natural forms, including beta- and
delta-tocopherol. Some research suggests that gamma-tocopherol may have unique
anticancer effects, but the evidence is far from conclusive.
For women,
the recommended dietary intake of vitamin E is 15 milligrams (mg) per day.
That's the equivalent of 22.5 international units (IU), the designation used on
many supplement labels. Most multivitamins contain 22–30 IU of vitamin E,
whereas vitamin E–only capsules may contain anywhere from 100 to 800 IU (or
higher).
Who needs a
vitamin E supplement? According to one recent large survey, the average woman
falls a little short, consuming only about 8.4 mg (12.6 IU) per day in food.
But that may not be accurate. An Institute of Medicine study indicates that
many people underreport the amount of fat and calories they actually consume,
including fats and oils used in cooking — a significant source of vitamin E.
Deficiencies of vitamin E are uncommon, except in people with unusual health
problems, such as difficulties with fat absorption or rare genetic disorders.
It's also possible that a person on a very low–fat diet might be deficient.
|
Food
sources of vitamin E |
||
|
Food |
Serving
size |
Mg
(IU) vitamin E* |
|
Wheat
germ oil |
1
tbsp |
20.3
(30.5) |
|
Fortified
cold cereal (Product 19, Total) |
1
cup |
14.0
(21) |
|
Sunflower
seeds, dry roasted |
1/4
cup |
7.8
(11.7) |
|
Almonds,
dry roasted |
1
oz |
7.8
(11.7) |
|
Canola
oil ** |
1
tbsp |
6.8
(10.2) |
|
Walnuts
+ |
1
oz |
6.7
(10) |
|
Sunflower
oil (65% linoleic) |
1
tbsp |
5.6
(8.4) |
|
Safflower
oil (over 70% oleic) |
1
tbsp |
4.6
(7) |
|
Hazelnuts
or filberts |
1
oz |
4.3
(6.5) |
|
Peanut
butter, fortified |
2
tbsp |
4.2
(6.3) |
|
Spinach,
cooked |
1
cup |
3.7
(5.6) |
|
Soy
milk |
1
cup |
3.3
(5) |
|
Raw
red peppers |
1
cup |
2.4
(3.5) |
|
Broccoli,
cooked |
1
cup |
2.4
(3.5) |
|
*Rounded
to the nearest tenth of a milligram/IU. Recommended daily intake of vitamin E
is 15 mg (22.5 IU). **Contains
more than 60% gamma-tocopherol, a form of vitamin E that some researchers
believe may be more beneficial than the alpha form. +Contains
mostly gamma-tocopherol. Other nuts containing gamma-tocopherol at similar
levels include pistachios and pecans. |
||
|
Source: USDA National Nutrient Database for Standard Reference. |
||
Antioxidant power overestimated?
Vitamin E's
main claim to a high reputation is its antioxidant properties. Antioxidants are
substances that protect cells against the effects of free radicals —
by-products of energy metabolism that may damage cell membranes and DNA. By
quelling free radicals, the thinking went, vitamin E might help prevent certain
diseases. But research is finding otherwise.
Heart
disease. Two large observational
studies from Harvard Medical School found that people who took at least 100 IU
of vitamin E per day had a lower risk of heart disease. But such studies rely
largely on the participants' own reports of their past dietary habits and
supplement use. When people were split at random into groups and assigned to
take vitamin E or a placebo, these findings were not corroborated. In nearly
all of the randomized controlled trials, vitamin E neither protected against
heart disease nor prevented further deterioration in people who already had
heart disease.
Cancer. The evidence on cancer has followed a similar pattern.
Some observational studies found that people who consumed more vitamin E were
less likely to develop breast, colon, or prostate cancer. But controlled trials
found no such advantage. For example, in one study, people taking vitamin E to
help prevent colon cancer were just as likely to develop colon polyps, which
are potential precursors to colon cancer, as those who didn't take the vitamin.
Dementia
and Alzheimer's disease. The
findings on dementia are somewhat conflicting. Once again, observational
studies suggested that taking vitamin E might protect against Alzheimer's
disease and other forms of dementia. One randomized trial also found that
vitamin E might delay the progression of Alzheimer's. But some researchers pointed
to flaws in the study's design, and the dose used was 2,000 IU per day — well
above the safe upper limit.
Cataracts. Controlled trials of vitamin E supplements have not
confirmed observational findings of a lower incidence of cataracts in regular
vitamin E users.
Experts urge caution
The U.S.
Preventive Services Task Force, an independent panel that issues health
advisories, has found insufficient evidence to recommend for or against vitamin
E supplementation for preventing cardiovascular disease or cancer. The American
Heart Association goes further. Its guidelines on preventing heart disease and
stroke in women specifically advise against using antioxidant supplements such
as vitamin E. And the Alzheimer's Association recommends that patients take vitamin
E only under the care of a physician. One reason for their concern is that
high-dose vitamin E can interfere with the blood's clotting ability, raising
the risk of hemorrhagic (bleeding) strokes. People who take blood-thinning
medications such as warfarin (Coumadin) should be especially cautious.
Currently,
the official safe upper limit (UL) of intake —that is, the maximum daily amount
thought to be unlikely to cause harm in most healthy people — is 1,000 mg
(1,500 IU) per day. If you take synthetic vitamin E, the UL is 733 mg (1,100
IU), because bleeding problems can occur at lower levels of the synthetic form.
Not surprisingly, the study has prompted calls from some experts for the UL to
be revised. Another potential pitfall is that, like any supplement, vitamin E
may be used as a substitute for strategies with proven benefits, such as a
healthful diet and exercising.
What to do
Many
researchers haven't given up hope for lower doses of vitamin E, but that will
depend on the results of ongoing trials. In the meantime, try to get most of
your vitamin E from food, because there's strong evidence that diets containing
large amounts of vitamin E-rich foods are good for your health. If you're
uncertain about how much you're getting from your diet, you may want to
consider taking a supplement containing no more than 150–200 IU per day. At
that level, taking vitamin E still falls under the rubric of "shouldn't
hurt and might help."
