When you think about blood pressure, your kidneys may not come to mind.
But when these bean-shaped organs sustain damage or are thrown off balance — perhaps by heavy salt intake — both your blood pressure and your heart may feel the repercussions.
Your kidneys filter more than 120 quarts of blood each day. They pull toxins and unwanted fluid from cells throughout the body, then send them to the bladder.
Eating too much salt can make it harder for your kidneys to remove fluid, which builds up in your system and increases your blood pressure.
Over time, excessive salt intake can lead to high blood pressure (hypertension), which stiffens and narrows the blood vessels. Blood and oxygen flow to key organs decreases. So the heart tries harder to pump blood throughout the body, which further increases blood pressure.
“Elevated blood pressure, particularly over a long period of time, puts an incredible strain on the heart,” says Benico Barzilai, MD, Head of Clinical Cardiology. It can enlarge the heart’s left pumping chamber and weaken the heart muscle (heart failure).
Unchecked hypertension can also damage the artery walls, which begin to collect fat, leading to heart disease and potentially heart attack or stroke.
“The best way to prevent a heart attack is to stop the arteries from becoming damaged,” says Dr. Barzilai.
You can see this chicken-or-egg effect with high blood pressure and kidney disease as well. Hypertension puts extra pressure on the kidneys’ filtering units, which can lead to scarring. This impairs the kidneys’ ability to regulate fluid, which increases blood pressure.
“If this cycle is not stopped, it can lead to kidney disease and kidney failure,” says hypertension specialist George Thomas, MD. “High blood pressure and uncontrolled diabetes are the most common causes of kidney disease.”
Unfortunately, the vast majority of people with kidney disease don’t realize they have it. The signs and symptoms may be attributed to other conditions, and usually appear when the kidneys have already begun to fail. Here are symptoms to watch for, according to the National Kidney Foundation:
If you are experiencing any of these symptoms — particularly if you are at risk of kidney disease because you’re over age 60, have high blood pressure, have diabetes or have a family history of kidney failure — talk to your doctor about your salt intake.
Salt affects people differently. “Some people can consume sodium with no effect on their blood pressure. But for others, even a slight increase in sodium intake wreaks havoc on the kidneys’ ability to regulate fluid, and increases blood pressure,” says Dr. Thomas.
Salt sensitivity is most prevalent among the middle-aged and elderly, the overweight and obese, and African-Americans.
One of the first things your doctor will recommend is modifying your lifestyle by:
Yet “many people do not respond to salt restriction and lifestyle changes alone,” notes Dr. Barzilai. They may also need medication to lower your blood pressure, such as:
Besides encouraging you to keep hypertension and diabetes under control, your doctor may test you annually for kidney disease.
Working with your doctor to ensure that salt intake is not raising your blood pressure and impacting your heart and kidneys can have a dramatic impact on your health and longevity.