Low blood pressure & Water

Submitted by Thiruvelan on Thu, 10/30/2014
Hypotension & Water

Maintaining an adequate plasma volume is crucial. Everyone should drink 42 to 85 ounce (1.25 to 2.5 liters) of water or other fluid per day. Many elderly people do not drink this much.

Dehydration is a factor responsible for low blood pressure and thus experts suggest drinking more water to improve blood pressure.

Drinking water prevents dehydration; additionally, it also increases the blood volume, which subsequently increases the blood pressure.

Does drinking water raise blood pressure?

Researchers at Vanderbilt University Medical Center have observed that

Ordinary water (without any additives) does more than just quench thirst. It increases the activity of the sympathetic fight or flight response in the nervous system, which raises alertness, blood pressure and energy expenditure.

Some years ago a team of doctors first observed water's curious ability to increase blood pressure, in patients who had lost their baroreflexes (the system controls blood pressure within a normal range).

The investigators found water increases sympathetic nervous system activity and constrict blood vessels, which prevent pooling of blood in the lower extremities in people with postural hypotension.

However, water does not significantly raise blood pressure in healthy young subjects with intact baroreflexes.

Does water reduce dizziness & fainting?

The American Red Cross conducted a study of water drinking as a method for reducing fainting.

The study found that drinking 16 ounces of water before blood donation reduced the fainting response by 20 %. This is not only applicable for blood donation also people with low blood pressure, because blood volume problem is common among them.

Thus, drinking water reduces dizziness and other low bp symptoms.

Can I drink water with a pinch of salt to raise BP?

Water raises blood pressure; however, a similar volume of saline (salt-containing solution) does not raise blood pressure. It suggests that plain water (without salt) might be important.

The water dilutes the plasma that reduces salt concentration (hypo-osmolality), which is responsible for blood pressure raising effect of water. Still the normal role for this physiological system is not clear.

How much BP rise can expect from drinking water?

Drinking 16-oz (500-mL) of water helps to expand plasma volume. Subsequently, within a few minutes, it increases the standing systolic blood pressure by more than 20 mm Hg.

This blood pressure raise extend for about 2 hours and improves the low-pressure symptoms. Additionally, water does promote weight loss because it raises sympathetic nervous system activity and consequently energy expenditure.