Men who regularly take vitamin E
supplements eventually have a higher
risk of developing prostate cancer,
compared to other men of the same
age and overall health who don't,
researchers from the Cleveland Clinic
reported in JAMA (Journal of the
American Medical Association). The
authors say their findings clash with
what most people would have
expected.
As background information, the
researchers wrote:
"Lifetime risk of prostate cancer in the
United States is currently estimated to
be 16 percent. Although most cases
are found at an early, curable stage,
treatment is costly and urinary, sexual,
and bowel-related adverse effects are
common."
Epidemiological and preclinical
evidence had so far pointed towards
prostate cancer preventive benefits
associated with vitamin E and
selenium supplements.
The authors added:
"The initial report (December 2008) of
the Selenium and Vitamin E Cancer
Prevention Trial (SELECT) found no
reduction in risk of prostate cancer
with either selenium or vitamin E
supplements but a statistically
nonsignificant increase in prostate
cancer risk with vitamin E. Longer
follow-up and more prostate cancer
events provide further insight into the
relationship of vitamin E and prostate
cancer."
Eric A. Klein, M.D. and team set out to
determine what the long-term effects
of vitamin E and selenium might be
on prostate cancer risk among men of
relatively good health. They gathered
data on 35,533 males from 427 study
centers in Puerto Rico, Canada and
the USA, who were randomized
between August 2001 and June 2004.
They only selected males with a PSA
measure below a certain level, a
digital rectal examination that did not
point towards a suspicion of prostate
cancer, aged 50 years or more for
African-Americans and 55 for other
males.
In the primary analysis, 34,887 men
were randomly selected into one of
the four following groups:
Selenium group - 8,752 men received
200 micrograms of selenium per day
Vitamin E group - 8,737 men received
400 IU per day
Double group - 8,702 men received
both selenium and vitamin E
Placebo group - 8,696 men received
supplement-looking dummy tablets
There was a 7-year minimum and 12-
year maximum planned follow-up .
Data was gathered and analyzed up to
July 2011.
A total of 521 additional prostate
cancers have been reported since the
initial report - in the following groups:
Placebo group - 113 cases
Vitamin E group - 147 cases
Selenium group - 143 cases
Combination group - 118 cases
In all three treatment groups there
was a higher rate of prostate cancer
compared to the placebo group. The
vitamin E group had a 17% higher risk
of developing prostate cancer
compared to those in the placebo
group.
When looking at the total prostate
cancer rate, not just the increase since
the initial report, the numbers were
as follows:
Placebo group - 529
Vitamin E group - 620
Selenium group - 575
Combined group - 555
It became apparent during the
participants' third year in the trial that
those in the vitamin E group had a
higher risk compared to those in the
placebo group. The researchers said
that "The elevated risk estimate for
vitamin E was consistent across both
low- and high-grade disease."
The authors wrote:
"In this article, we report an
observation of important public health
concern that has emerged with
continued follow-up of SELECT
participants. Given that more than 50
percent of individuals 60 years or
older are taking supplements
containing vitamin E and that 23
percent of them are taking at least 400
IU/d despite a recommended daily
dietary allowance of only 22.4 IU for
adult men, the implications of our
observations are substantial. "
The greater prostate cancer risk
among those in the vitamin E group
was only detectable after extended
follow-up. This means that the effects
of vitamin E can linger, even after the
individual stops taking the
supplement. For any study to be
meaningful and relevant, the authors
say the follow-up period needs to be
long.
The researchers also added that when
assessing the benefits and drawbacks
of micronutrients as dietary
supplements, studies need to be
large-scale , population- based, and
randomized.
They wrote:
"The observed 17 percent increase in
prostate cancer incidence
demonstrates the potential for
seemingly innocuous yet biologically
active substances such as vitamins to
cause harm. The lack of benefit from
dietary supplementation with vitamin
E or other agents with respect to
preventing common health conditions
and cancers or improving overall
survival, and their potential harm,
underscore the need for consumers
to be skeptical of health claims for
unregulated over-the -counter
products in the absence of strong
evidence of benefit demonstrated in
clinical trials."
Vitamin E
Vitamin E belongs to a group of fat-
soluble compounds, including
tocopherols and tocotrienols. Y-
tocopherol is the most common type
of vitamin E in the American diet, and
can be found in margarine, soybean
oil, corn oil and dressings. α-
Tocopherol is the second most
common form of vitamin E in the
North American diet, it is also the
biologically most active, and can be
found in sunflower oil, safflower oil,
and wheat germ oil.
Vitamin E is a fat-soluble antioxidant
that halts the production of reactive
oxygen species that are formed when
fat is oxidized.
α-tocopherol form of vitamin E
Reports have indicated that vitamin E
may have benefits for:
A vitamin E pre- cursor may protect
against a kind of breast cancer
Aging
Arthritis
Better diabetes control
Certain skin conditions
Improving the immune system in
elderly people
Lowering chronic obstructive
pulmonary disease (COPD) in about
10% of both non-smokers and
smokers
Male fertility
Parkinson's disease
PMS (premenstrual syndrome)
Protecting from Alzheimer's disease
The prevention of heart disease
supplements eventually have a higher
risk of developing prostate cancer,
compared to other men of the same
age and overall health who don't,
researchers from the Cleveland Clinic
reported in JAMA (Journal of the
American Medical Association). The
authors say their findings clash with
what most people would have
expected.
As background information, the
researchers wrote:
"Lifetime risk of prostate cancer in the
United States is currently estimated to
be 16 percent. Although most cases
are found at an early, curable stage,
treatment is costly and urinary, sexual,
and bowel-related adverse effects are
common."
Epidemiological and preclinical
evidence had so far pointed towards
prostate cancer preventive benefits
associated with vitamin E and
selenium supplements.
The authors added:
"The initial report (December 2008) of
the Selenium and Vitamin E Cancer
Prevention Trial (SELECT) found no
reduction in risk of prostate cancer
with either selenium or vitamin E
supplements but a statistically
nonsignificant increase in prostate
cancer risk with vitamin E. Longer
follow-up and more prostate cancer
events provide further insight into the
relationship of vitamin E and prostate
cancer."
Eric A. Klein, M.D. and team set out to
determine what the long-term effects
of vitamin E and selenium might be
on prostate cancer risk among men of
relatively good health. They gathered
data on 35,533 males from 427 study
centers in Puerto Rico, Canada and
the USA, who were randomized
between August 2001 and June 2004.
They only selected males with a PSA
measure below a certain level, a
digital rectal examination that did not
point towards a suspicion of prostate
cancer, aged 50 years or more for
African-Americans and 55 for other
males.
In the primary analysis, 34,887 men
were randomly selected into one of
the four following groups:
Selenium group - 8,752 men received
200 micrograms of selenium per day
Vitamin E group - 8,737 men received
400 IU per day
Double group - 8,702 men received
both selenium and vitamin E
Placebo group - 8,696 men received
supplement-looking dummy tablets
There was a 7-year minimum and 12-
year maximum planned follow-up .
Data was gathered and analyzed up to
July 2011.
A total of 521 additional prostate
cancers have been reported since the
initial report - in the following groups:
Placebo group - 113 cases
Vitamin E group - 147 cases
Selenium group - 143 cases
Combination group - 118 cases
In all three treatment groups there
was a higher rate of prostate cancer
compared to the placebo group. The
vitamin E group had a 17% higher risk
of developing prostate cancer
compared to those in the placebo
group.
When looking at the total prostate
cancer rate, not just the increase since
the initial report, the numbers were
as follows:
Placebo group - 529
Vitamin E group - 620
Selenium group - 575
Combined group - 555
It became apparent during the
participants' third year in the trial that
those in the vitamin E group had a
higher risk compared to those in the
placebo group. The researchers said
that "The elevated risk estimate for
vitamin E was consistent across both
low- and high-grade disease."
The authors wrote:
"In this article, we report an
observation of important public health
concern that has emerged with
continued follow-up of SELECT
participants. Given that more than 50
percent of individuals 60 years or
older are taking supplements
containing vitamin E and that 23
percent of them are taking at least 400
IU/d despite a recommended daily
dietary allowance of only 22.4 IU for
adult men, the implications of our
observations are substantial. "
The greater prostate cancer risk
among those in the vitamin E group
was only detectable after extended
follow-up. This means that the effects
of vitamin E can linger, even after the
individual stops taking the
supplement. For any study to be
meaningful and relevant, the authors
say the follow-up period needs to be
long.
The researchers also added that when
assessing the benefits and drawbacks
of micronutrients as dietary
supplements, studies need to be
large-scale , population- based, and
randomized.
They wrote:
"The observed 17 percent increase in
prostate cancer incidence
demonstrates the potential for
seemingly innocuous yet biologically
active substances such as vitamins to
cause harm. The lack of benefit from
dietary supplementation with vitamin
E or other agents with respect to
preventing common health conditions
and cancers or improving overall
survival, and their potential harm,
underscore the need for consumers
to be skeptical of health claims for
unregulated over-the -counter
products in the absence of strong
evidence of benefit demonstrated in
clinical trials."
Vitamin E
Vitamin E belongs to a group of fat-
soluble compounds, including
tocopherols and tocotrienols. Y-
tocopherol is the most common type
of vitamin E in the American diet, and
can be found in margarine, soybean
oil, corn oil and dressings. α-
Tocopherol is the second most
common form of vitamin E in the
North American diet, it is also the
biologically most active, and can be
found in sunflower oil, safflower oil,
and wheat germ oil.
Vitamin E is a fat-soluble antioxidant
that halts the production of reactive
oxygen species that are formed when
fat is oxidized.
α-tocopherol form of vitamin E
Reports have indicated that vitamin E
may have benefits for:
A vitamin E pre- cursor may protect
against a kind of breast cancer
Aging
Arthritis
Better diabetes control
Certain skin conditions
Improving the immune system in
elderly people
Lowering chronic obstructive
pulmonary disease (COPD) in about
10% of both non-smokers and
smokers
Male fertility
Parkinson's disease
PMS (premenstrual syndrome)
Protecting from Alzheimer's disease
The prevention of heart disease
Tidak ada komentar:
Posting Komentar