The
information in this column is intended for informational
purposes only, and does not constitute medical advice or
recommendations by the author. Please consult with your
physician before making any lifestyle or medication changes, or if you
have any other concerns regarding your health.
VITAMIN
E & VITAMIN C: NO IMPACT ON CARDIOVASCULAR
DISEASE RISK
Vitamin
E and
Vitamin C are essential vitamins with powerful antioxidant properties. These vitamins are able to
neutralize toxic “free
radicals,” which are normal byproducts of metabolism in our bodies. In theory, antioxidants
should be able to prevent
these dangerous free radicals from damaging the cells in our body,
including
the endothelial cells that form the interior lining of our arteries. While previous laboratory
studies, typically using
human cells growing in a culture dish or laboratory animals, have shown
that antioxidant
vitamins do indeed soak up free radicals, clinical studies of these
vitamins in
humans have been far less encouraging (as is often the case in medical
research, unfortunately).
Now,
a new
long-term prospective clinical trial, involving nearly 15,000 male
physicians
aged 50 and above, is casting further doubt that Vitamin E and Vitamin
C supplements
are capable of reducing the risk of cardiovascular disease. In this 10-year study,
which was conducted at
Harvard University, volunteers were randomized to receive a daily
Vitamin E
pill (400 IU) or an identical sugar pill (placebo), as well as a daily
Vitamin
C pill (500 mg) or a similarly identical placebo.
Unlike many previous cardiovascular disease
prevention studies that have evaluated these two vitamins, the vast
majority of
the Physicians’ Health Study II volunteers were healthy, and had no
clinical
evidence of heart disease, peripheral vascular disease, or stroke upon
entry
into the study (only 5 percent of these volunteers had any evidence of
any cardiovascular
diseases at the time they joined this research study).
This study appears in the current issue of
the Journal of the American Medical
Association.
I
won’t belabor
the results of this very large high quality clinical study, because the
findings
were very straightforward… and disappointing.
There was no significant difference in the incidence of
heart disease,
heart attacks or strokes between the various randomized groups of male
volunteers in this antioxidant vitamin study.
Neither Vitamin E nor Vitamin C supplementation appeared
to have any favorable
impact on the incidence of cardiovascular disease in these otherwise
healthy
middle-aged male physicians. On
the
other hand, there was a 74 percent relative increase in the risk of
stroke
among the men who were randomized to receive Vitamin E.
The type of stroke most often observed in the
men taking Vitamin E was hemorrhagic (bleeding) stroke, which is not
entirely
surprising, as Vitamin E can cause thinning of the blood, particularly
at
higher doses.
In
summary, this
is yet another disappointing clinical research trial looking for
potential
health benefits associated with Vitamin E and Vitamin C supplementation. In this particular study,
there appeared to
be no benefit associated with
Vitamin
E or Vitamin C in reducing the incidence of heart disease, heart attack
or
stroke in healthy middle-aged men who took these vitamin supplements
for an
average of 8 years. Unfortunately,
the
results of this study mirror the similarly disappointing results of
recent
prospective Vitamin E and Vitamin C cancer prevention studies which
have,
likewise, not shown any apparent
benefit in reducing the incidence of cancers.
Moreover, taking regular supplements of Vitamin E, beyond
the current
minimum daily recommended requirement, may also increase your risk of
hemorrhagic stroke.
This
study joins
an ever greater collection of clinical research studies that have shown
no significant
health benefits associated with Vitamin E and Vitamin C
supplementation. For
folks like me, who have long hoped for
different research outcomes related to these two antioxidant vitamins,
it may
be time to have another look at my vitamin and supplements drawer, and
to
update my inventory based upon the results of this study.
DOES
LACK OF SLEEP
INCREASE STROKE & HEART ATTACK RISK IN HYPERTENSIVE PATIENTS?
As I sit at my
computer this evening, composing this week’s column, I am struggling to
stay
awake after a very long week with little sleep.
My head is pounding in time with my fingers as they tap on
my laptop’s
keys. My eyes don’t
seem to want to stay
in focus, either. Annoying
aches in the
back of my head and neck nicely round out all of my other symptoms of
sleep
deprivation.
It’s
no secret
that Americans are sleeping less and less these days.
We spend more time at work, and less time in
bed, than most other people around the world (we also take fewer
vacations than
most of the rest of the world).
Bleary-eyed, chronically irritable, and perpetually dazed,
we trudge
through each passing day wishing we could get just an hour or two of
additional
sleep before being awakened by our alarms each morning.
But beyond merely feeling miserable much of
the time (or, on a more serious note, risking an automobile accident
while
driving), there may actually be significant health risks associated
with
chronic sleep deprivation. Indeed,
recent
clinical studies have suggested that, for most people, an average of 7
hours of
sleep per night may be optimal for good health.
Slumbering away for significantly fewer (or more) hours
may, in fact,
increase a person’s risk of serious illness, or even death.
Now,
a new study
from Japan, where people also tend to get by on much less sleep than
the rest
of the world does, suggests that chronic sleep deprivation may
substantially
increase your risk of stroke, heart attack and death due to cardiac
events,
especially if your blood pressure tends to increase at night while you
sleep. This
prospective clinical research study,
just published in the Archives of
Internal Medicine, evaluated 1,255 healthy older adults with
uncomplicated high
blood pressure. The
average age of the
volunteers in this study was 70 years (range: 33 to 97 years), and the
average
duration of patient follow-up was 4 years. Continuous
blood pressure readings were
performed on these patient volunteers for 24-hour periods at home, on a
weekly
basis, and all patients were closely followed for signs of heart attack
(fatal
or non-fatal) and stroke over the duration of the research study. All patient volunteers
also maintained a “sleep
diary” on the evenings when their blood pressure was being monitored.
In
this study of
hypertensive patients, a nightly sleep duration of less than 7.5 hours
was
associated with nearly twice the risk of experiencing a cardiovascular
event (i.e.,
stroke, non-fatal heart attack, or fatal heart attack) when compared to
hypertensive patients who reported more than 7.5 hours of sleep per
night.
Other
studies,
looking primarily at younger and healthier patients, have also noted an
increased risk of death (from any cause) when the average nightly
duration of
sleep drops below 7 hours. This
particular study is unique in that the patient volunteers all had high
blood
pressure, and all of them underwent 24-hour continuous monitoring of
their
blood pressure. This
latter feature is
important because nocturnal rises in blood pressure have previously
been linked
with an increased risk of cardiovascular events, but blood pressure
increases
at night have not previously been studied in combination with duration
of sleep.
When
the
researchers in this study looked specifically at those patients who
experienced
a rise in their blood pressure at night, the risk of cardiovascular
events
associated with sleeping less than 7.5 hours per night increased
dramatically. When
this group of patient volunteers was compared
to patients who slept more than 7.5 hours per night and
who had the normal pattern of stable or decreased blood
pressure at night, the risk of serious cardiovascular events was more
than 4
times as common in the patients with rising blood pressure and sleep durations of less than 7.5
hours. Thus, among
older patients with hypertension,
increased nocturnal blood pressure
and decreased duration of sleep,
when
combined, were associated with a very high risk of heart attack, death
from
heart attack, and stroke.
There
are some important
limitations in this study that should be considered. First
of all, none of the patient volunteers in
this study were observed in sleep lab, and so the sleep durations
reported by
the patients are subject to a great deal of inaccuracy. (The most accurate method of
determining if patients
are asleep or awake is to perform a formal sleep lab study, including
the use
of continuous EEG recordings of brainwave activity).
Secondly, because the study volunteers were
not observed by the researchers at night, it is not possible for this
research study
to determine if the rise in nocturnal blood pressure was, in some way,
directly
and solely responsible for the increase in cardiovascular events
observed in the
“blood pressure risers” who slept less than 7.5 hours per night. In fact, multiple
health-related factors are
known to cause elevated blood pressure at night, including sleep apnea,
some medications,
alcohol, obesity, diabetes, and nightmares, among others, and some of
these same
factors are, themselves, directly associated with an increased risk of
cardiovascular
events. For
example, there is a well-known
pattern of nocturnal heart attacks, and many experts believe that sleep
apnea
is the likely culprit in many such cases. According
to this theory, the periods of
decreased oxygen flow to the heart that occur when patients with sleep
apnea
momentarily stop breathing may give rise to heart attacks when
coexisting coronary
artery disease is also present. (Patients
with sleep apnea typically have multiple and asymptomatic “apneic”
episodes throughout
the night, and oxygen levels within the blood and vital organs can drop
precipitously during these brief spells when breathing stops.)
Therefore, in
order to validate the conclusions of this study, the study would have
to be
repeated under conditions requiring that all patient volunteers undergo
formal
sleep lab testing in addition to continuous blood pressure monitoring. Nonetheless, there is ample
previous research
data suggesting that chronic sleep deprivation is associated with a
higher risk
of serious illness, and with an increased risk of death. So, on that note, I’m
calling it a night, and
I’m off to bed now to try and catch some much-needed sleep.
Disclaimer:
As always, my advice to readers is to seek the advice of your physician
before making any significant changes in
medications, diet, or level of physical activity.
