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Surprising Side Effects of Eating Bananas, According to Science

From digestion to hydration, this portable fruit packs a powerful punch.
FACT CHECKED BY Kiersten Hickman

Whether you like to cook with bananas or you simply love enjoying a banana with a scoop of peanut butter, bananas can provide your body with a myriad of health benefits that leave your body feeling incredible. But it's important to know all of the side effects that happen when you eat bananas, particularly when it comes to the color of the banana when you peel it. Read on to discover the surprising side effects of eating bananas on the regula.

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You'll get a good amount of potassium.

banana slices

The star nutrient in bananas! One small 7-inch banana can provide your body with around 422 milligrams of potassium, which is about 9% of your recommended intake. If you need even more of a potassium boost for the day, bananas are also closely tied with many other fresh produce options. Potatoes, sweet potatoes, spinach, and lentils all have as much or significantly more potassium than bananas. Especially white potatoes, which have double the amount of potassium as bananas!

Here are 21 High Potassium Foods That Keep Your Muscles Healthy and Strong.


Bananas can uniquely transform from starch to sugar.

Peeling a banana from the bottom

As bananas turn from green to spotted, they become sweeter. Spotted bananas have a greater impact on blood sugar, and digest more quickly. In fact, as bananas ripen, the glycemic index doubles! Eating bananas while they are still slightly green ensures you get the best blood sugar-stabilizing effect.

For people with diabetes, Toby Smithson, MS RDN, from Diabetes Everyday, says "…bananas are a source of carbohydrate so they are not an all you can eat food. An extra small banana is considered one serving of carbohydrate, or 15 grams [of] carbs!"

Here's One Surprising Side Effect of Eating Bananas you need to know more about.


You may experience constipation.

Peanut butter banana toast

An unripe banana could be worsening your constipation issues. Due to the slow digestion of a green banana's unique molecules—pectin fiber and resistant starch—individuals who already have slow digestion should take caution. To be on the safe side, drink plenty of water when eating "green-er" bananas.

Conversely, those who struggle with diarrhea or loose stools may actually benefit from adding this fibrous fruit to their diet to slow things down. Kids are particularly sensitive to the digestive effects of the fiber in bananas.

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You'll get a boost of electrolytes.

Man peeling banana to eat

Bananas are naturally packed with almost 10% of your daily requirement for potassium and magnesium, also known as the essential minerals that make up electrolytes. That's a combo that's hard to find in nature. Electrolytes move our water and energy into the muscles instead of the bloodstream. This means that your muscles get the fuel they need to recover from exercise so that you can get back to the gym with less fatigue! Eat a banana post-workout, drink plenty of fluids, and your muscles will thank you.


Eating bananas hydrates your body.

sliced bananas with nut butter on white plate

Bananas are organically hydrating due to their electrolyte content. In fact, combining electrolytes with your water intake has shown to be more hydrating than water alone! Especially before and after exercise, hydrating with electrolytes is important.

"Potassium is lost in your sweat when you exercise, which often causes muscle cramps. Potassium and sodium levels must be replenished along with water if you have exercised over an hour," says Lacy Ngo, MS, RDN, author of The Nourishing Meal Builder.


Bananas can balance your blood pressure.

banana cut up
Eiliv-Sonas Aceron / Unsplash

Sodium intake among Americans has significantly increased over time, while potassium intake has decreased over time. This phenomenon has created the perfect storm for high blood pressure from the standard American diet.

The potassium content of bananas, and many other fruit and vegetables, balances sodium in the body, directly impacting blood pressure. Because sodium and potassium work together in the body, adding bananas to a high sodium diet may positively impact blood pressure.


The fiber will keep you full for hours.

Woman peeling banana

Bananas—specifically green bananas—are high in two types of fiber: pectin and resistant starch. A medium-sized banana is a good source of fiber as it contains three grams of total fiber. These fibers slow down digestion and keep you full longer. Keep in mind: the more spotted the banana appears, the less fiber it has, and the faster you'll digest it!

Here's why fiber i100 Unhealthiest Foods on the Planet The #1 Thing To Eat Every Day To Lose Weight For Good.

Caroline Thomason, RDN
Caroline is a women's health Registered Dietitian and diabetes educator based in Northern Virginia. Read more about Caroline
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