Vitamin A toxicity. Is it a problem?
Hi. I'm Dr. Chris Masterjohn of
chrismasterjohnphd.com. And this is
Chris Masterjohn Lite, where the name of the game is
"Details? Shmeetails. Just tell me what works!"
And today we're going to talk about vitamin A toxicity.
Vitamin A is a nutrient, and it is not a toxin.
However, like with many other things, too
much of a good thing can become a bad
thing. And vitamin A when it accumulates
in the body can cross a certain
threshold that contributes to toxicity.
So, how do you know if you have toxicity?
Well, the most common symptoms are nausea,
vomiting, and headache. As vitamin A
toxicity gets worse, it can cause
anorexia, blurred vision, scaling skin,
hair loss in the form of an autoimmune
condition known as alopecia, organ damage,
and in very rare cases death. So, it's a
serious concern, but in the vast majority
of cases, we're looking at things like
nausea, vomiting, and headache as the big
warning signs. Now, nausea, vomiting, and
headache can have many causes, so we want
to consider two other important pieces
of data. One is how much vitamin A have
you been exposed to, and the other is
some lab tests. If we limit our
discussion of vitamin A to vitamin A
found in food and to vitamin A
supplements that are either naturally
occurring in the case of liver or cod
liver oil supplements, or are normal
fat-soluble, such as retinol palmitate. And
we're not talking about retinol acetate,
and we're not talking about any forms
that have been prepared specifically to
be more water-soluble for people who
have trouble absorbing vitamin A through
the normal processes. So, if we
limit our discussion to normal fat-soluble vitamin A,
for a 150-pound adult, we
would require more
than 10,000 IU of vitamin A taken over
months to years consistently every day
as an absolute minimum for what's been
reported to cause toxicity. The average
case is over 150,000 IU taken every day
for months or years to
lead to toxicity. Now,
this is in people who are not supplementing with
other nutrients. So, vitamin D for example
is very protective against vitamin A
toxicity. And if you look at the case
reports of vitamin A toxicity, the doses
that cause toxicity when people are also
supplementing with vitamin D are far higher.
In these cases vitamin A toxicity
requires an average dose of more than
300,000 IU per day taken every day for
months or years. On the other hand,
whereas vitamin D is protective, using
water-soluble preparations of vitamin A
makes it more dangerous. There you can
see toxicity with ten times lower doses,
and you can see toxicity in a shorter
period of time ranging from weeks to
months of taking it every day instead of
from months to years. The other important
piece of data is lab tests. So, the lab
tests that are likely to be elevated in
vitamin A toxicity are as follows starting
with the ones that are most common.
Most commonly the serum vitamin A
is going to be elevated above the top
of the reference range. The next most
likely test to be elevated above the top
of the reference range is gamma-glutamyl transferase.
The next most likely is
triglycerides. The next most likely after
that is alkaline phosphatase. The next
most likely after that is the prothrombin time.
After that, cholesterol. After that,
AST, one of the liver enzymes, so called.
After that, bilirubin. And the test that
is commonly found to be elevated but is
the most least likely out of all of these
to be elevated is serum calcium.
So, together when you're looking at the
signs and symptoms, and you're looking at
the exposure to vitamin A, and you're
looking at the blood tests, you can
assess the probability that you have
been exposed to toxic amounts of
vitamin A over time. You don't need every single piece of
data to add up nice and neatly, but you
need things from each category to make
it make sense to consider vitamin A
as the thing that's probably at the root
of whatever problem you're trying to fix.
Now, there are some special additional
concerns about excess vitamin A.
Excess vitamin A even when it's not at toxic
levels can worsen osteopenia and
osteoporosis when someone is deficient
in the other nutrients needed to protect
against those diseases, particularly
calcium and vitamin D. So, this is not a
matter of vitamin A being toxic. It's a
matter of vitamin A being out of balance
with the other nutrients. If you're
running deficient in calcium and
deficient in vitamin D, and yet you're
running on the high end of normal
vitamin A, that imbalance is going to be a
problem, but what you really want to do is pull the other
nutrients up to be in balance with it.
There are concerns about too much of
vitamin A going into the first eight
weeks of pregnancy, and I have some of my
own concerns about vitamin A and fatty
liver. So, I'm going to make special
episodes about those coming up next
because I believe that those
issues deserve special episodes.
Finally, if you want all this information about
signs and symptoms, about exposure
amounts, and about different tests to run
for vitamin A toxicity, all in one place
integrated into a comprehensive guide
for managing nutritional status for
vitamin A and all the nutrients, then all
this stuff can be found in
Testing Nutritional Status: The Ultimate Cheat Sheet.
If you don't have your copy yet,
you can get your copy at
chrismasterjohnphd.com/cheatsheet.
And you can use the code: LITE5
that's L I T E and the number 5
LITE5 to get five dollars off.
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All right. I hope you found this useful.
Signing off, this is Chris Masterjohn of
chrismasterjohnphd.com. This has been
Chris Masterjohn Lite.
And I will see you in the next episode.