Sodium and Arterial Function: A-salting our Endothelium

Sodium and Arterial Function: A-salting our Endothelium

September 16, 2019 87 By Ewald Bahringer


“Sodium and Arterial Function:
A-salting our Endothelium” If you put people
on a low salt diet, meaning only getting twice as
much sodium as they need, as opposed to a
usual salt diet where they’re getting
five times more, you get a significant
improvement in artery function. Lower salt,
better arterial function; suggesting heart
protective effects beyond just blood
pressure reduction. Now this was after dropping
people’s salt intake by about a teaspoon
a day for two weeks. What if you only
dropped salt intake by like a half
teaspoon a day? You still get a significant improvement
in artery function, and it happens within
just two days of reducing one’s
salt intake. Or even after
a single meal. A high salt meal,
which is to say just a typical amount
of salt consumed in a commonly
eaten meal, can significantly suppress
artery function within 30 minutes. Here’s what happens 30, 60, 90, 120 minutes
after a meal with just a pinch
of salt in it. Here’s what happens
after the same meal, but with a quarter
teaspoon of salt in it. A significant suppression
of arterial function. Now is this in addition
to the spike in blood pressure
from salt or because of the spike
in blood pressure? If you take people with
normal blood pressure and give them a
bowl of soup containing how much salt
a regular meal might contain, their blood pressure
goes up over the next
three hours compared to the
same soup with no added salt. Now this doesn’t happen
to everyone; this is just the
average response. Some people are resistant
to the effects of salt on their
blood pressure. So, what if
you repeated the artery function
experiment on them? Unfortunately the title ruins
the suspense and gives it away. As you can see,
even in people whose blood pressure is
unresponsive to salt intake, they still suffer
significant suppression of their artery
function. So even independent of
any effects on blood pressure, salt hurts our arteries and that harm begins
within minutes of it going into
our mouth for our major
arteries and even our itty
bitty blood vessels. Using something called
laser Doppler flowmetry, you can measure
blood flow in the tiny vessels
in our skin. Here’s blood flow
at baseline. Now to get the blood
vessels to open up they warmed
up the skin. The reason we
may turn pink when we get into
a hot bath is that the blood vessels in
our skin are opening up. And that’s
what happens. Big increase in blood flow
with the warming. But that’s on the
low salt diet. A high salt diet, starts out the same
at the beginning, but after the
same heating, there’s significantly
less blood flow. The arteries just don’t
seem to open up as well on a high salt diet,
unless… you inject vitamin C
into their skin. That seems to reverse
the salt-induced suppression of blood
vessel function. So if an antioxidant
reverses the salt effect, then the way salt may be
damaging our artery function is through
oxidative stress, the formation of free radicals
in our blood stream. But how? There’s an enzyme
in our body that can detoxify a million
free radicals per second, 24 hours a day,
7 days a week. But compared to
a low salt diet, if we consume a
normal salt diet, we suppress the
activity of this detoxifying powerhouse
of an enzyme. That may be
help explain why “this is your
artery function; this, is your artery
function on salt.” With our antioxidant enzymes
crippled by the salt all the excess
free radicals may be crippling
our arteries. But mop up those extra
free radicals up by infusing vitamin C
into the bloodstream, and artery function
returns to normal. Whereas on a
low salt diet, if you drip vitamin C
into people’s veins, nothing happens, because our antioxidant
enzymes are already taking care
of business and haven’t been shackled
by the sodium of a normal-salt diet. Whereas potassium, concentrated in fruits
and vegetables, soften the cells
that line our arteries and increase the
release of nitric oxide that allows our
arteries to relax, sodium in our blood
stiffens the cells lining our arteries
within minutes, and reduces nitric
oxide release. The more salt, the less
nitric oxide is produced. One salty meal, and not only
does our blood pressure go up but our arteries
literally stiffen. That’s why we
could figure out that too much salt
was bad for us 4,000 years ago. We don’t need a
double blind trial, maybe we don’t need to follow
people out for a decade. You may just have
to feed someone a bag of potato chips
and take their pulse.