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Banana Glycemic Index: Analyzing the Impact on Blood Sugar

Madison Holt, MS, RDN, LD

Published in Nutrition

8 min read

September 28, 2022
A bunch of fresh yellow bananas on a checked kitchen cloth against a white backdrop
A bunch of fresh yellow bananas on a checked kitchen cloth against a white backdrop

Bananas are a tropical and versatile fruit that is eaten all over the world. They can be eaten raw, but also may be fried, baked, added to desserts, or mixed in with baked goods.

This tasty fruit is thought to have been first cultivated in Southeast Asia and introduced to the Americas in the 14th century. Surprisingly, bananas only became common in the United States in the 19th century.

There are hundreds of different varieties of bananas, which each vary slightly in their nutritional profile depending on their ripeness and where they are grown. So, what are these nutritional benefits? And how might bananas affect your blood sugar? Read on to find out.

Types of Bananas

There are many varieties of bananas, but Cavendish bananas are the typical sweet, yellow banana you find in U.S. grocery stores. Other common banana varieties include red bananas, blue java bananas, and apple bananas.

Plantains are another type of banana that tend to be usually thicker and starchier than Cavendish bananas. Plantains are not usually eaten raw, but rather are cooked and often used in savory dishes. The majority of the world’s plantain production comes from Africa.

Apart from the variety of banana you’re eating, the level of ripeness can also affect nutritional content. When bananas are unripe, they contain more fiber and resistant starch than ripe, yellow bananas.

Green bananas are also firmer and can have a grassy, bitter taste to them. As they ripen, bananas turn yellow and their sugar content tends to increase. Overripe bananas, which become spotty and turn darker yellow or brown are the sweetest.

Nutritional Benefits of Bananas

As we’ve mentioned in past articles, the Dietary Guidelines for Americans recommends eating 1.5 to 2.5 cups of fruit per day. Fruits are great sources of nutrients like fiber, vitamins, potassium, and antioxidants. These nutrients can support heart health, immune system health, and digestive health.

Here’s a look at some of the nutritional benefits of medium-sized ripe bananas, overripe bananas (darker yellow or spotted brown), and plantains.

graphic with banana nutritional info

Bananas are considered a superfood because of all the nutrients packed into them. These fruits are a good source of vitamins and minerals like vitamin B6, vitamin C, potassium, and manganese.

Let’s take a look at some of the nutrients that make bananas good for you.

Vitamin B6

Bananas contain vitamin B6, a vitamin that plays a role in cognitive development, immune function, and metabolism. Some studies suggest that adequate intake of vitamin B6 may play a role in preventing some types of cancer, however more research is still needed to confirm this link.

Low levels of vitamin B6 have been associated with depression. Studies also show that low vitamin B6 levels can greatly increase the risk of cardiovascular disease.


Bananas are a good source of fiber, a carbohydrate found mainly in plant foods. Eating plenty of fiber can have a positive effect on your health with benefits such as supporting bowel health and reducing your risk of colorectal cancer.

A diet high in fiber can also reduce the risk of heart disease and support healthy blood sugar levels. Researchers have found that only five percent of Americans currently get enough fiber in their diet.


a girl holding some bananas

Bananas are a good source of potassium, a mineral that your body relies on for kidney, heart, and nervous system function. Potassium may also counter the effects of sodium on your blood pressure and is associated with a lower risk of stroke and all-cause mortality.

If you take an ACE-inhibitor to treat high blood pressure, the extra potassium in bananas may lead to a dangerously high potassium level in the body. Talk to your doctor to see if bananas and other potassium-containing foods are safe to eat.

Vitamin C

Vitamin C supports immune system function and is required for the production of collagen, which is a crucial component of the connective tissue that is important for wound healing. A ripe banana contains 12.5 milligrams of vitamin C.

Vitamin C is also an antioxidant, which means it helps to fight off free radicals in your body. Free radicals, which are molecules that can damage your cells and DNA, may increase the risk of cancer, heart disease, and other diseases.

Vitamin C may also play a role in regulating blood sugar. A 2019 study found that vitamin C may significantly decrease post-meal blood glucose levels.


someone slicing a banana

Bananas are also a source of manganese, a trace mineral that is involved in bone formation, reproduction, immune system response, and blood clotting. Manganese also has antioxidant action.

Deficiency in this mineral may increase the risk of type 2 diabetes and bone problems. The recommended daily intake of manganese is 1.8 milligrams for women and 2.3 milligrams for men. One banana contains 0.26 milligrams of this mineral.

Resistant Starch

Unripe bananas and plantains contain resistant starch, which is a type of starch that isn’t digested by the body. This compound works similarly to fiber and may lead to improved bowel health, improved glycemic and insulin response.

It may also have health benefits including helping to lower cholesterol and increasing fullness after meals (which has been observed in overweight men).

Bananas and Blood Glucose

a girl holding a banana

One ripe, medium-sized banana contains about 18 grams of sugar and 26 grams of carbs. While it’s possible for this amount of sugar to have a significant impact on your blood sugar, the exact effect may vary depending on your individual body and your overall diet.

According to biomedical researcher Dr. Steve Gendron, "the fiber in bananas can slow down the sugar rush to your blood. If you're watching your blood sugar levels, green bananas are best because they're lower in sugar and high in resistant starch." This can help to keep your glucose steady.

Another important factor to consider is the glycemic index, or GI scale, which is a tool that can sometimes help determine how quickly sugar from a food will enter your bloodstream and lead to blood sugar spikes. In general, bananas are considered to have a low GI, or low glycemic index. The GI of bananas can range from 30-75, depending on the type, with most varieties falling below 50.

If eaten in small quantities, bananas also have a low to moderate glycemic load, which is a measurement that takes the quality of your carbohydrate content and portion size into account. This means that bananas may have a smaller impact on blood sugar levels for some people, especially if eaten with other sources of fiber or protein.

Remember that the GI and GL systems are just one tool to help you know what may affect your blood sugar levels. It’s important to take into account your individual diet as a whole and what other foods you are eating alongside a banana.

If you're following a low-carb diet, have diabetes, or need to limit your carb intake for some other reason, consult with a dietitian or nutritionist or doctor to determine whether bananas are safe for you.

5 New Ways to Try Bananas

If you are wondering how to add bananas to your diet while reducing the risk of sharp glucose spikes, here are 5 great ways to do so.

1) Flourless Banana Bread Bars from The Big Man’s World

flourless banana bread bars

This flourless, gluten-free recipe is made from oats. Oats are high in fiber and have also been shown to reduce blood sugar levels and improve insulin sensitivity. This tasty bread also contains peanut butter, which may benefit heart health and add extra protein and fats to this dessert.


  • 4 cups rolled oats
  • 6-7 bananas (approximately 2 cups)
  • 1 cup peanut butter
  • Optional: ¼ cup chocolate chips

2) Spinach and Banana Smoothie From Hurry the Food Up

This simple and refreshing smoothie contains spinach, which is high in vitamins, minerals, and fiber. Spinach is also a great source of antioxidants, and has even been shown to lower blood pressure.

The peanut butter rounds this smoothie out with healthy fats, and using soy milk to blend it all together can add a dash of extra protein.


  • 1 medium banana
  • 1 handful spinach
  • 1 tablespoon peanut butter
  • 1¼ cup unsweetened plant-based milk (like soy, oat, almond, or coconut) or water

3) Baked Plantain Chips from Downshiftology

a plate and tray of plantain chips

Plantain chips are a popular snack in many parts of the world, and this version is baked instead of fried. You may want to opt for using a green plantain for lower sugar content.


  • 1 green plantain
  • ½ tablespoon avocado oil
  • sea salt, to taste

4) Sweet Potato Banana Muffins from Eat This, Not That

a plate with sweet potato banana muffins

These muffins are gluten free, dairy free, and contain no added sugars. The sweet potatoes add some extra vitamin A and fiber and are also high in antioxidants that may help prevent certain cancers and cardiovascular disease.


  • 2 ripe bananas, mashed
  • 3 eggs
  • ½ cup mashed sweet potato
  • ¼ cup canned unsweetened coconut cream
  • 1¾ cup almond flour
  • ¼ cup tapioca flour
  • 1 teaspoon baking powder
  • 1 teaspoon baking soda
  • 1 teaspoon ground cinnamon
  • 1 teaspoon ground ginger
  • ½ teaspoon salt

5) Black Bean Plantain Chili from Connoisseurus Veg

a plate with black bean plantain chili

This vegan chili is a great combination of sweet and spicy. The black beans are high in fiber and phytonutrients, while the tomatoes provide lycopene, an antioxidant that may help lower cholesterol and prevent cardiovascular disease.


  • 1 tablespoon vegetable oil
  • 1 medium onion, diced
  • 1 red bell pepper, diced
  • 3 garlic cloves, minced
  • 2 cans black beans
  • 1 can crushed tomatoes
  • 1 can diced tomatoes
  • 1 tablespoon chili powder
  • 1½ teaspoon ground cumin
  • 1 teaspoon smoked paprika
  • ½ teaspoon ancho chili powder
  • 2 ripe plantains
  • Salt and pepper
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Heather Davis, MS, RDN, LDN

Reviewed by: Heather Davis, MS, RDN, LDN

Heather is a Registered and Licensed Dietitian Nutritionist (RDN, LDN), subject matter expert, and technical writer, with a master's degree in nutrition science from Bastyr University. She has a specialty in neuroendocrinology and has been working in the field of nutrition—including nutrition research, education, medical writing, and clinical integrative and functional nutrition—for over 15 years.