This is why you shouldn't use zinc picolinate
as your zinc supplement.
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
zinc picolinate. I get a lot of
questions about why I don't recommend
zinc picolinate because other people do
recommend zinc picolinate. And so today
I want to show you why.
Shown on the screen is a study
where 15 students were given
four different zinc supplements in a
double-blind crossover trial. Each zinc
supplement contained 50 milligrams of
elemental zinc. And you can see at the
top that the zinc picolinate
is in the green diamonds, the zinc
citrate is in the yellow circles, the
placebo is in the blue stars, and the
zinc gluconate is in the pink triangles.
And you can see in these graphs that in the
upper left, we have the zinc that wound
up in the hair. In the upper right, we
have the urine. In the lower left,
we have red blood cells, and in the
lower right, we have serum. Now, notice
that two episodes ago, I said that to
measure zinc status, you want the plasma
zinc. The reason you want the plasma zinc
is because in plasma is where we have
what we call the exchangeable zinc pool,
which is the small portion of zinc that
is fully liberated that is moving
in between the different tissues and is
moving back and forth between the
tissues and the diet. In other words, in
order to become usable,
zinc that you supplement with or that you eat in your
diet must enter the plasma zinc pool.
And we do not have the plasma zinc pool
measured here at all, so we don't
actually know which of these best
improved the one metric that we care
most about for zinc status. But one thing
that we can see if we just look at the
green lines is that zinc picolinate did
look best in hair. Zinc picolinate did
look, I wouldn't say best, but it did
cause the most zinc to wind up in the
urine. It did cause the most zinc to wind
up in the red blood cells, but none of
these improved serum zinc. And one of the
things that we want to see if we know
that there was a change is we want to
see these lines move from close together
to farther apart. Now, an optimistic
interpretation of this is to say, "Look,
although none of these things made a
difference in the serum zinc, and
although we don't have plasma zinc, the
measurement that we would want, the zinc
picolinate did increase red blood cell zinc more than
the others." And that's a
good thing. And maybe it's a good thing
that it increased hair zinc more than
the others. But it also increased urine
zinc more than the others, which means
that you're peeing out the zinc
picolinate. One pessimistic way of
looking at this data is to say maybe the
reason that more wound up in the urine
is because picolinate binds so tightly
to zinc that the zinc never gets
liberated to enter the plasma zinc pool
and instead just accumulates as zinc
picolinate in all these tissues. So you
have zinc as zinc picolinate just being
stuffed into the hair, the zinc gets into
the red blood cells, but it's as zinc
picolinate, and it just accumulates there
without being able to fulfill any of the
functions of zinc because it never gets
released from the picolinate, and then a
lot just winds up in the urine again as
zinc picolinate. So to look at this a
little further, we're going look at one
more study. In this case, we're looking at
a study where rats were given diets with
or without picolinic acid, and the
researchers looked at what happened to
the zinc in their diet. So in this case,
we're not looking at zinc picolinate
supplementation. We're just
saying what happens to zinc
when you add the picolinate
to the diet of the animal. As you go
across the graphs on the screen, you see
fecal zinc, urinary zinc, total zinc excretion,
net zinc absorption, and zinc retention.
You can see that fecal zinc
was decreased a little bit by the picolinic acid,
but it wasn't statistically significant.
You can also see that net
zinc absorption was increased a little
bit by the picolinic acid, but again, it
wasn't statistically significant. On the
other hand, let's look at the loss of
zinc through the urine and how it
impacted the net retention of zinc.
Adding picolinic acid to the diets of
the animals increased the urinary zinc
by about eightfold. So just adding the
picolinic acid to the diet of the
animals with everything else being the
same causes them to spill eight times as
much zinc into their urine.
As a consequence of this, the total zinc excretion
was increased, and the net zinc
retention was negative both
with and without the picolinic acid.
But it was fairly close to
zero without the picolinic acid, which
means that the incoming zinc and
outgoing zinc is in balance, and it was
significantly negative when the picolinic
acid was added. So when we look at
the rat study, it looks like just adding
picolinic acid to the animal makes the
picolinic acid bind to the zinc and
carry it into the urine. When we take
that information and we look at the
human study, the human study where zinc
picolinate caused a better
increase in red blood cell zinc, hair
zinc, and urine zinc, then it looks like
the zinc picolinate, when you feed it to
the human as zinc picolinate,
carries the picolinate, carries the zinc into
various tissues, where it probably never
gets freed to act as zinc, and it carries
zinc right into the urine.
So with these and with the absence of
tests showing even equivalence let alone
superiority at increasing plasma zinc,
and with the known track record of the
forms that I recommended in the last
episode, in on the ground curing zinc
deficiency, something that's extremely
well-studied because the
World Health Organization lists
zinc deficiency as something that
impacts half the world's population,
so this is something very well studied,
with a known track record of
cheap forms of zinc, like zinc sulfate,
curing zinc deficiency, I cannot
recommend zinc picolinate.
The available data indicate that the forms
that I've recommended in the last
episode are adequate and the adequacy of
zinc picolinate is at best questionable.
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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.
