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One Major Side Effect of Eating Too Many Bananas, Says Science

If you're a banana lover, there's something you need to know.
FACT CHECKED BY Kiersten Hickman

As they constitute one of the main food groups, of course, it's healthy to regularly eat fruit, and with an easily-removed peel and no excess juices to make your hands sticky, bananas are one of the simplest fruits to consume. While they're great for digestive health and contain many much-needed vitamins, it's important to not eat an excessive amount of bananas, according to dietitians. (Related: The 7 Healthiest Foods to Eat Right Now)

Bananas are a great source of potassium, but too much potassium in our bloodstream can result in a condition called hyperkalemia, which is the medical term for when the potassium level in a person's blood is higher than normal. When left untreated, hyperkalemia can sometimes result in serious heart problems. It can also result in other scary side effects, like muscle weakness and temporary paralysis.

While hyperkalemia is most commonly caused by acute kidney failure and chronic kidney disease, a study by the National Institute of Mental Health linked a patient's case to excessive banana consumption, as the patient would consume upwards of 20 bananas a day.

"A dosage that is higher than 18 grams of potassium can increase the risk of hyperkalemia in adults," says Amber O'Brien, RD from the Mango Clinic.

A single banana typically contains approximately 420 milligrams of potassium, so it would take a lot of bananas to hit that point, but if you're a banana lover and are also eating a lot of other foods that contain high potassium, like avocados and spinach, it might be best to back off a bit.

There are also certain groups of people that are at higher risk for hyperkalemia, including those with "congestive heart failure, chronic kidney disease, diabetes or those taking certain blood pressure medications which impact potassium levels," says Diana Gariglio-Clelland, a registered dietitian who works at

If you fall into one of those groups, Gariglio-Clelland recommends speaking with a doctor about consuming bananas or other foods that are high in potassium.

If you want to keep bananas in your diet, in moderation, of course, here are some ways that the fruit can help you lose weight.

Erin Yarnall
Erin Yarnall is a freelance reporter from the Chicago area. Read more about Erin
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