Does Drinking Water Reduce Blood Pressure? What About Dehydration & BP?
By Dr Joe
One of the queries I get often on this blog is: does drinking water reduce blood pressure? If we flip that question on its head, the question can be framed differently.
What will that be? It will be: does dehydration affect blood pressure?
I shall answer both questions for you on this page and you shall know the truth regarding water and blood pressure reduction.
Plus, you also get to know briefly the importance of water to our bodies, why we need water, how much water to drink and the effect of over-consumption of water on blood pressure too.
And you get my recommendation on the best drink for high blood pressure.
The way I am going to approach the subject is this. I will discuss the effect of dehydration on blood pressure first, then talk about how drinking water (rehydration) affects your blood pressure afterwards.
Kinda make sense to do it that way.
But if you’re in a hurry and only want to know if drinking water reduces blood pressure, then you can scroll towards the later part of this article for an answer straightaway.
Using water as a blood pressure remedy can seem a little far fetched but there’s some truth in it, within reason.
I know that some people do take it a little too far. I have read some people claim that drinking just water only without any medications whatsoever lowered their blood pressure and now they live life happily ever after.
We live in a world where anyone can make any claim regarding anything. This is worse online. After all, people make all sorts of claims about diabetes and cancer online. These claims range from the sublime to the ridiculous.
So, it’s not surprising we have people making ridiculous claims about blood pressure treatment at home…and even low blood pressure.
Before I delve into the possibility of dehydration causing high blood pressure and the fact that drinking water is one way you can lower your blood pressure naturally, let’s talk about the importance of water to our bodies briefly first.
How important is water to our bodies?
Well, make no mistake about it. Water is very important to our very survival. Without water we won’t be here on this planet.
This is exemplified in the fact that the average adult body is made up of 55 – 60% water. Babies have even more water content in their bodies. Babies are made up of 75% water until they are 1 year old when their water content drops to 65%.
Water plays a huge role in our bodies. From joint lubrication to keeping our brain well hydrated. Your brain is 75% water, believe it or not. Our brains have the same amount of water as you’ll find in ripe bananas. Our lungs are to a large extent a wet organ too.
Let’s not forget body temperature regulation. Water plays a major role in heat generation for our bodies.
In fact, without water, there will be metabolic mayhem in our bodies. Undoubtedly so.
Why do we need to drink water daily?
We need to drink water daily because some of our body functions mean we lose water every day. We lose water through urine. We lose water through bowel movement. We lose water through sweat. We lose water through our breathe.
All of that water loss needs to be replaced.
If we fail to replace the water lost through those bodily functions, dehydration will result.
But there has to be a fine balance between how much we are losing and how much we replace.
This fine balance prevents dehydration and over-hydration. Both over-hydration and dehydration are bad for our health.
Indeed, too much water in the body from over-hydration is just as bad for our blood pressure as dehydration is.
So, does dehydration affect blood pressure?
Yes, it does. And dehydration does affect blood pressure through 3 different mechanisms.
Dehydration is a potent trigger for a whole host of metabolic events.
Let’s just talk about hormonal events that occur when you are dehydrated. Because this is how dehydration can affect your blood pressure.
The 1st Dehydration-BP Elevation Mechanism
Dehydration leads to renin secretion. Renin is an enzyme produced in the kidneys in response to low blood volume or low salt levels in the blood.
When renin is released, it triggers the conversion of another pro-enzyme called angiotensinogen to angiotensin 1.
A chain of events follows. I don’t want to bore you with the details. All you need to know is that; the end result of that chain of events is the production of another hormone called aldosterone.
The job of aldosterone is to conserve the mineral called sodium. Of course, wherever there’s sodium, water follows. Aldosterone raises blood pressure as a result.
Aldosterone raises blood pressure by preventing the kidneys from losing sodium in urine. Conserve as much sodium as possible.
And because water follows the sodium saved by the aldosterone (don’t forget that sodium is salt), our blood pressure gets elevated when we are dehydrated.
Blood pressure rises when salt and water are retained in the body.
This chain of events caused by dehydration is initiated by renin. In fact, this research tells us a 24-hour episode of dehydration induced a 3-fold increase in renin activity in the body.
That’s the power of water deprivation with a ripple effect on our blood pressure.
That’s one mechanism.
The 2nd Dehydration-BP Elevation Mechanism
A second mechanism of how dehydration can affect our blood pressure is via another hormone called Anti Diuretic Hormone (ADH).
ADH is released from the hypothalamus in our brain when dehydration signals are received by the brain.
Anti Diuretic hormone as the name implies stops you losing water in urine. Meaning ADH will concentrate your urine to conserve water in the body.
By reducing the amount of urine excreted by the kidneys, blood volume increases and blood pressure rises as a conseqence. This is a protective mechanism to prevent the fatal consequences of dehydration on your body.
This action in turn will elevate your blood pressure too.
The 3rd Dehydration-BP Elevation Mechanism
There’s a 3rd mechanism through which dehydration elevates your blood pressure. It involves a direct effect on the tiny vessels we call capillaries.
Dehydration causes these capillaries to “narrow up”. When these tiny vessels become narrow, the pressure inside them rises causing a blood pressure elevation.
So, whereas initially dehydration leads to a lower blood pressure, compensatory mechanisms move things in the opposite direction leading to high blood pressure.
That’s how our body protects itself from harm caused by dehydration.
So, does drinking water reduce high blood pressure?
Yes, drinking water does reduce high blood pressure but with a caveat. You only need to drink what your body requires for the effect of water on blood pressure to be within the safe margins.
You just need to stay well hydrated. Nothing more.
The reason water does cause a reduction in blood pressure is the reverse of the events I discussed above.
Staying well hydrated by drinking plain water, mineral water or decaffeinated tea means you suppress renin release. Inhibiting the release of renin means you avoid elevated aldosterone levels.
Remember I said, aldosterone causes blood pressure elevation, so we don’t want to trigger its release.
We also want to suppress Anti Diuretic Hormone release by drinking enough.
Drinking enough water staves off those hormonal events that lead to blood pressure rise. Meaning drinking adequate water helps us lower high blood pressure naturally.
The effect of drinking water to lower or reduce blood pressure may not be as dramatic as eating foods that lower blood pressure quickly, but it helps a great deal.
What about over-hydration…
Does drinking too much water cause high blood pressure?
If you remember, I did say, to use water as a natural blood pressure remedy, you only need to drink enough to stay well hydrated.
This means you don’t need to go over-board because drinking too much water can actually cause high blood pressure.
It’s got to be finely balanced.
What’s the fine balance?
How much water should I drink a day?
Well, conventional teaching has always been that we should aim to drink 8 glasses of 8-oz glass per day.
But that advice is changing.
The amount of water we need to drink a day largely depends on our weight and our environment.
The recommended daily water intake does vary but it ranges from 2.5 liters – 3.7 liters for men and between 2 liters – 2.8 liters for women.
Obviously, that recommended daily water intake is not set in stone. Our daily water intake can be dialled up or down depending on how healthy we are, how old we are, how active we are and how hot the environment we are located is.
So, drink enough water or decaffeinated beverage like tea or mineral water or even coconut water to stay hydrated but don’t overdo it.
Because when you drink too much water especially within a short time interval, you can cause salt dilution in the body.
This is called hyponatremia.
This happens accidentally with athletes as they are physically active and feel they need to drink more and more.
How Water Intoxication comes about and the effect on your Blood Pressure
Whereas the dehydrated brain compensates by releasing that pesky Anti Diuretic Hormone (ADH), over-consumption of water is also sensed by the brain. Over-consumption inhibits the release of the ADH.
The inhibition of Anti Diuretic Hormone causes dilution of sodium and water retention occurs. Because the kidneys can’t keep up with the resulting amounts of dilute urine.
The net result is water intoxication and a direct effect of this water retention is high blood pressure.
So, please do not drink water in excess in the hope that that would lower your high blood pressure instantly and naturally. It won’t.
What’s the best drink for high blood pressure?
Whatever you do when considering the best drink for high blood pressure, do not think for one second that alcohol will help you lower your blood pressure. It won’t.
I have written extensively about alcohol and blood pressure here.
Next drink you really do not want to be hydrating yourself with is coffee. Quite apart from the fact that coffee does make the body acidic, the caffeine in coffee does cause a rise in blood pressure.
So, coffee is not the best drink for high blood pressure.
In its place, you can consider drinking herbal teas for high blood pressure. The herbal teas have phytochemicals in them that will help you lower your blood pressure naturally.
Herbal teas do not have caffeine in them; hence they are ideal for BP control. Visit this page for a complete list of herbal teas that reduce high blood pressure.
A very good drink to consider is cacao drink but make sure you make the drink from original cacao powder. Make your cacao drink from unprocessed cacao not the processed sugar-loaded variety.
When also thinking about the best drink for high blood pressure, coconut water is an excellent drink to consider. You can consume coconut water for high blood pressure because it is mineral-rich.
Coconut water contains lots of potassium just like bananas. Foods and drinks high in the mineral potassium are one of the best things to consume to control high blood pressure.
Let me know what you think about what you have read here. Leave your comments below anything relating to water and indeed high blood pressure.
Suggested further reading:
Drink THIS 2 Hours Before Bedtime to Sleep Better