Expert: Sue Kayton Date: 2/6/2008 Subject: Biology
Question QUESTION: Hello :)
Why are bananas good for my heart?
My grandad has bad kidneys and needs to eat bananas.
thankyou
ANSWER: Good question. The answer is a bit complicated.
When people have a bad heart or bad kidneys, the doctor often gives them medication to make the heart and kidney's jobs easier.
The heart pumps blood, so if there's a little less blood, the heart doesn't have to pump so hard. The main part of the blood is the red blood cells, and the rest of the blood is mostly water.
The kidneys filter the bad stuff out of the blood, so if there is less blood, then the kidneys also don't have to work so hard.
So the pills the doctor gives (they are called diuretics) make the blood have less water in it. This helps the heart and helps the kidneys.
Where does the water go? The kidneys take it out of the blood and turn it into urine (pee). But the kidneys aren't perfect. When they take water out of the blood, they also take out potassium. Your body needs potassium for the heart to beat right.
So people who take diuretic pills need extra potassium in their diets. Bananas and oranges have lots of potassium. People who don't like bananas or oranges can take potassium pills.
People (like you and me) who don't take diuretic pills get enough potassium in our normal diets that we don't need potassium pills. But we still enjoy bananas and oranges!
I hope this answered your question, and hope that your grandfather's kidneys heal and improve.
-Sue Kayton
San Francisco, California, USA
---------- FOLLOW-UP ----------
QUESTION: thankyou sue! but what does potassium do exactly? i have seen on tv that it burns in water, how can we have it in our blood if it sets on fire?
Answer People's blood, like the blood of all animals, is basically salt water with other stuff (like red blood cells) in it. The two most common salts are sodium chloride (table salt) and potassium chloride. Canned food, frozen food, and fast food always has huge amounts of sodium chloride salt added to it for flavor, and most Americans sprinkle sodium chloride salt on their food, so they never run short of sodium, even if they are taking diuretics. But they can run low on potassium.
Potassium is key to making the electrical system of the heart beat properly. If there is too little potassium, the heart will beat irregularly, too slowly, or have other heart problems.
