“The Effect of Drinking Water
on Adrenal Hormones” Drink a few cups of water,
and within three minutes the level of the adrenal gland
hormone, noradrenaline, in your bloodstream
can shoot up 60%. Have people drink two cups of
water with electrodes stuck in their legs, and within 20 minutes you
can document about a 40% increase in bursts of fight-or-flight nerve activity.
Chug two or three cups of water and blood flow squeezes down
in your calves and arms, clamping down nearly in half,
as arteries to your limbs and skin constrict to divert blood to your core.
That’s why, for example, drinking water can be such a safe, simple, effective
way to prevent yourself from fainting— known medically as syncope.
Fainting is the sudden, brief loss of consciousness caused by
diminished blood flow to your brain. About 1 in 5 people experience this
at least once, and about 1 in 10 may have repeated episodes, causing
millions of emergency room visits and hospitalizations every year. Though fainting can be caused by heart
problems, it is most often triggered by prolonged standing—because
blood pools in your legs— or strong emotions, which can cause
your blood pressure to bottom out. About 1 in 25 people have what’s
called blood-injury-injection phobia, where getting a needle stick, for
example, can cause you to faint. More than 150,000 people experience
fainting or near-fainting spells each year when they donate blood. All you have to do to help prevent
yourself from getting woozy though is just chug two cups of water
5 minutes before getting stuck. The secret isn’t bolstering your
overall blood volume. I mean, drinking 2 cups of water—even a whole quart—
and your blood volume doesn’t change more than like 1 or 2%. It’s due rather
to the shift in the distribution of blood toward your center, caused by the noradrenaline-induced
peripheral artery constriction. Water drinking stimulates as
much noradrenaline release as drinking a couple of cups
of coffee or smoking a couple unfiltered cigarettes. If the
simple act of drinking water causes such a profound
fight-or-flight reaction, why doesn’t it cause our heart to
pound and shoot our blood pressure through the roof? It’s like the diving
reflex I talked about in the last video. When we drink water, our body
simultaneously sends signals to our heart to slow it down,
to still your beating heart. You can try it at home. Measure your heart rate before
and after drinking two cups of water. Within 10 minutes your heart rate should
slow by about four beats per minute, and by 15 minutes you should
be down six or seven beats. One of the ways scientists
figured this out is by studying heart transplant patients. When you move a heart from one
person to another, you have to sever all the attached nerves. Amazingly,
some of the nerves grow back. But still, give healed heart transplant
patients two glasses of water and their blood pressure goes
up as much as 29 points. The body is unable to
sufficiently quell the effect of that burst of noradrenaline. Some people have a condition
known as autonomic failure, in which blood pressure regulation
nerves don’t work properly, and their pressures can dangerously
skyrocket over 100 points after chugging two cups of water.
That’s how powerful an effect the simple act of drinking
a glass of water can be. And the only reason it doesn’t
happen to all of us is that we have an even more powerful counter-
response to keep our heart in check. It reminds me of the poor woman
who had a stroke after taking the ice bucket challenge due
to an insufficient diving reflex to tamp down all that extra
noradrenaline release. The remarkable water effect can
be useful for people suffering from milder forms of autonomic failure
such as orthostatic hypotension, which is when people get
dizzy standing up suddenly. Drinking some water before getting out
of bed in the morning can be a big help. But what about that metabolic boost?
With so much more noradrenaline being released, with your adrenal gland
hormones in overdrive, might drinking a few glasses of water cause
you to burn more body fat? Could tap water be like
a safe form of ephedra: all the weight loss with a nice
slowing of your heart rate instead? Researchers decided to put it
to the test, which we’ll explore next. Video source: https://www.youtube.com/watch?v=GramY3jaEk0
