over the past 15 years or so there's
been much interest in vitamin D and
increasing use of vitamin D
supplementation by the population and so
we were interested in studying more
about whether this increased supplement
use has led to increasing vitamin D
levels in the population as well as
perhaps increased toxicity from vitamin
D as well acute toxicity from vitamin D
results from very high levels of vitamin
D in the blood and that leads to what we
call hypercalcemia or high blood calcium
that we determine by measuring the
calcium level in the blood and that can
have serious consequences in terms of uh
even be life-threatening with the
Rochester epidemiology project is a
large data medical database related to
the residents of Olstead County
Minnesota primarily and that follows
those residents of Olstead County over
more than 40 years in terms of having
their medical records that are all
linked and subjects who are part of the
omstead residents in hestad County
who've given consent to use their
medical records data for the purposes of
research are included in this study and
it includes over
95% of the population so the unique
features of about that are that it
provides an opportunity to study the
rates of occurrence of various diseases
over time in a particular population we
identified residents of hestad County
over a 10-year period between 2002 and
2011 and who had measurements of their
vitamin D levels and we found over
20,000 subjects who had their vitamin D
levels measured
and identified those who had high
vitamin D levels which we defined as
more than 50 and the units for that
measurement are nanograms per milliliter
and I mentioned that because there are
other units for measuring vitamin D so
it's important when you're comparing
numbers to compare apples with apples we
found that 8% of the people who had
their vitamin D levels measured had
levels more than 50
and about less than 1% had levels over
100 yet we found that even those with
high levels of vitamin D over 50 there
was not an increased risk of
hypercalcemia or elevated serum calcium
with increasing levels of vitamin D we
found as well that women and those over
AG 65 were at the highest risk of having
vitamin Vin D levels over 50 and that's
a group that often
takes uh vitamin D supplementation as
well so that's not an unexpected finding
and the actual occurrence of levels over
50 increased over that 10-year period
from nine up to
233 per 100,000 people we were surprised
by that degree of dramatic increase in
uh vitamin D
and we also noted that only one case
among over those 10 years uh that we
were able to identify had true acute
vitamin D
toxicity with a level of
364 for their vitamin D and that person
had been taking Vitamin D supplements of
50,000 units every day for more than 3
months along with uh calcium supplement
mation as well which would make that
hyper calcemia or elevated blood calcium
even worse I think several things would
be important to take home from this one
is that acute toxicity from vitamin D
supplementation is very rare and it is
fairly safe to take in the short term
however there is not enough information
about the long-term effects of having
vitamin D levels over 50 and The
Institute of medicine has expressed some
concern about the possibility of adverse
effects related to long-term vitamin D
uh levels over 50 including an increased
risk of Falls or fractures some cancers
cardiovascular disease and even death
however the risk of those is much
greater if your vitamin D level is too
low so there it is good to be taking a
vitamin D supplement if you need it but
more is not necessarily better the level
of vitamin D supplementation that will
generally give you a uh vitamin D level
of more than 50 is or up at about 50 is
4,000 units a day so my advice for
doctors would be if your patients are
taking more than 4,000 units a day that
it would be reasonable to check their
blood vitamin D levels to make sure that
they are not too high and it is also
important for doctors to ask their
patients about the doses of Vitamin D
supplements that they are using because
even capsules as containing as much as
50,000 units of vitamin D are available
without prescription and they if taken
on a daily basis could lead to toxicity
as we observed in that one case I think
further study needs to be done on the
long-term effects of vitamin D levels
over 50 even though they've found some
associations with Adverse Events it may
be that people who are sicker tend to
take more Vitamin D supplements and that
may be why that association between
higher vitamin D levels and certain uh
illnesses exist so association between
two things doesn't mean that one caused
the other