Vitamin D
could cut the risk of flu infection in
children by half, the report claims
The risk of
children suffering from flu can be halved if
they take vitamin D, doctors in Japan have
found. The finding has implications for flu
epidemics since vitamin D, which is
naturally produced by the human body when
exposed to direct sunlight, has no
significant side effects, costs little and
can be several times more effective than
anti-viral drugs or vaccine.
Only one in
ten children, aged six to 15 years, taking
the sunshine vitamin in a clinical trial
came down with flu compared with one in five
given a dummy tablet. Mitsuyoshi Urashima,
the Japanese doctor who led the trial, told
The Times that vitamin D was more effective
than vaccines in preventing flu.
Vitamin D was
found to be even more effective when the
comparison left out children who were
already given extra vitamin D by their
parents, outside the trial. Taking the
sunshine vitamin was then shown to reduce
the risk of flu to a third of what it would
otherwise be.
Altogether
354 children took part in the trial, which
took place during the winter of 2008-09,
before the swine flu epidemic. Vitamin D was
found to protect against influenza A, which
caused last year’s epidemic, but not against
the less common influenza B.
The trial,
which was double blind, randomised, and
fully controlled scientifically, was
conducted by doctors and scientists from
Jikei University School of Medicine in
Tokyo, Japan.
The children
were given a daily dose of 1200 IUs
(international units) of vitamin D over a
period of three months. In the first month
children in the group taking the vitamin
became ill just as often as those taking the
dummy tablet. But by the second month, when
the vitamin level in the children’s blood
was higher, the advantage of the vitamin was
clear.
The Japanese
scientists, writing in the American Journal
of Clinical Nutrition, say that the
anti-viral drugs zanamivir and oseltamivir
reduce risk of flu infection by 8 per cent
in children who have been exposed to
infection, compared with a 50 per cent or
greater reduction with vitamin D.
Anti-virals
are also too expensive, and possibly too
toxic, to be given to the population as a
whole whereas vitamin D has additional
benefits. The sunshine vitamin not only
prevents bone fractures but is also believed
to reduce risks of cancer, heart disease,
diabetes and other illness, including
various bacterial as well as viral
infections.
The Japanese
finding supports a theory that low blood
levels of the sunshine vitamin occurring in
winter explain why flu epidemics generally
peak between December and March.
Vitamin D
activates the innate immune system, enabling
the body to produce several proteins such as
defensin and cathelicidin which trigger cell
activity and disable viruses.
Dr Urashima
said: “Vitamin D and vaccine work by quite
different mechanisms. Vitamin D enhances
innate immunity while vaccine enhances
acquired immunity. So we do not have to
select only one way of prevention, rather we
should do both ways, I think.”
Dr John
Oxford, professor of virology at Queen Mary
School of Medicine, London, said: “This is a
timely study. It will be noticed by
scientists. It fits in with the seasonal
pattern of flu. There is an increasing
background of solid science that makes the
vitamin D story credible. But this study
needs to be replicated. If it is confirmed
we might think of giving vitamin D at the
same time as we vaccinate.”
From The
Times March 15, 2010
(Richard
Cannon/The Times)
Oliver Gillie
Death, CVD
Risk Declines in People Who "Normalize"
Vitamin-D Levels—
March 18,
2010 (Atlanta, Georgia) -- Adding heft to
the hypothesis that
vitamin-D
deficiency is linked to cardiovascular
disease, a new study
has found
that people with low vitamin-D levels who
managed to normalize
their levels
were significantly less likely to develop
cardiovascular
events over
up to six years of follow-up.
The study was
presented as a poster by Dr Tami L Bair
(Intermountain
Medical
Center Heart Institute, Murray, UT) earlier
this week at the
American
College of Cardiology (ACC) 2010 Scientific
Sessions.
According to
coauthor Dr Joseph B Muhlestein
(Intermountain Medical
Center Heart
Institute), the study looked at baseline and
subsequent
vitamin-D
levels in 9491 subjects with known vitamin-D
deficiency,
rechecked
their vitamin D, then compared subsequent
rates of death,
coronary
artery disease, MI, heart failure, stroke,
and renal failure
among those
who managed to bring up their vitamin-D
levels with those
who remained
vitamin-D deficient. A cut point of <30 ng/mL
was used to
define
vitamin-D deficiency.
"This wasn't
a randomized trial, but all of these
patients started with
low vitamin
D, and then the question is, if they treated
their vitamin
D, did it
have an effect? We don't know what they did
. . . the
presumption
is that they were told their vitamin D was
low, then started
supplementation or got their swimsuit out
and went into the sun a lot to
treat it."
Getting to
Normal
After a mean
of one-year of follow-up, those who had
normalized their
vitamin-D
levels were significantly less likely to
have died, developed
heart
failure, or developed coronary artery
disease. A composite end
point,
looking at all outcomes combined, showed a
highly statistically
significant
reduction among those with normalized
vitamin-D levels.
Muhlestein
drew particular attention to the 30% reduced
risk of death in
the
normalized vitamin-D group. "A 30% reduction
in risk is about the
same you
could hope to get from taking a statin or
treating your blood
pressure, so
we thought it was certainly promising. It
doesn't eliminate
the need for
a real randomized trial, although I'm trying
to figure out
a good way to
do one."
There are a
number of vitamin-D trials under way, most
notably VITAL, a
National
Institutes of Health (NIH) study, launched
in January.
But
Muhlestein is concerned that the NIH trial
may come up empty-handed
for two
reasons. For one, the trial, he says, is not
measuring baseline
levels or
checking whether patients actually reach the
optimal vitamin-D
range in the
intervention arm. "I can see why they aren't
[measuring
vitamin D at
baseline], because if they find vitamin D is
deficient is
it ethical to
say, 'I want you to stay vitamin-D
deficient'?"
Vitamin-D
deficiency is already known to increase the
risks of skeletal
disease, he
notes. But without knowing if participants
actually
normalize
their levels, it will be impossible to link
normalization with
an effect on
events.
His second
concern is with the dose chosen in VITAL:
2000 international
units (IU)
per day. "What I've found is that there are
lots of my
patients who
don't become normalized with 2000 units, so
2000 units may
not be enough
to treat the really deficient patients."
But What's
Normal?
In fact,
Muhlestein and colleagues conducted a second
study, also
presented as
a poster during the ACC meeting, trying to
identify the
optimal level
of vitamin D by categorizing over 31 000
patients into
three levels
of vitamin D. When those levels were then
linked to rates
of 10 adverse
outcomes (most of them cardiovascular), the
authors
demonstrated
decreasing risk of adverse outcomes with
increasing
vitamin-D
levels, with a vitamin D level >43 ng/mL to
be the cutoff
point for
optimal.
Currently,
they point out, a level of 30 ng/ML is
considered
"normal"--that cut point may be too low,
based on their analysis.
But also of
note, "above 43 ng/mL there was no added
benefit,"
Muhlestein
observed. "So if your level was 70 ng/mL,
you were good, but
you weren't
any better than if [your level] was 43 ng/mL."
As for
whether vitamin D can be too high,
Muhlestein noted that there
are problems
with vitamin-D toxicities typically
associated with
hypercalcemia,
but these tend to arise in people with
levels higher than
100 ng/mL,
and many people believe the level must be
well over 150
ng/mL. "The
only way I know of that people can get
vitamin D that high
is by
overdosing on prescription vitamin D, which
is supposed to be
taken once a
week. If someone were to make a mistake and
take it once
per day, they
might get vitamin-D toxicity."
The findings
from both studies have convinced Muhlestein
that vitamin-D
deficiency is
worth treating, but he urges physicians to
make sure they
check to see
what a patient's vitamin-D levels are to
begin with and to
adjust the
dose accordingly. Individualization is
essential, he noted,
which is one
reason he's worried about the blanket
2000-IU approach
being used in
VITAL.
"Effective
dose varies from patient to patient, which
is one of the
problems with
the NIH trial. No one is going to become
toxic on 2000 IU
per day, but
there will be lots who are at the highest
risk who are not
going to
become normalized."
Source:
http://www.medscape.com
O
THANKS
FOR HELPING US HELP OTHERS!
O
