Bananas in a store

Bananas are the most popular fruit in the US. On average Americans consume more than 25 pounds a year per capita. That’s about 100 bananas per person and the trend is on the rise. Bananas are full of nutrition but still, there is a rumor that bananas should be avoided because they are fattening and full of sugar. Let’s look at what happens to your body when you eat a banana to find out if there is any reason this conveniently packaged energy fruit should be avoided.

What are bananas?

Bananas are the fruit of the banana plant. They grow in large hanging clusters, which are made out of tiers, each containing up to 20 bananas. These tiers (or hands) are the bunch of bananas you can buy in the supermarket. Although most of the bananas in shops come from plantations in Latin America, bananas are a fruit produced widely all over the world with India and China being the top producers. Bananas are a non seasonal crop and are available all year round.

Bananas on a tree

Most of the bananas consumed are sweet yellow dessert bananas that are eaten raw. Nevertheless they can also be pink, black and even striped. Plantains are a variety of bananas that need to be cooked before eaten because of their higher starch content.

In stores you can choose between unripe and ripe bananas. Unripe bananas are green and firmer, while ripe bananas are bright yellow with brown spots. Ripe bananas are more sweet because enzymes in bananas convert the starch content into sugar.

differently ripened bananas

Bananas are sweet and incredibly nutritious

Bananas contain a bunch of vitamins, minerals and fiber prepackaged conveniently in single serving sizes. One medium banana (126 g) has about 110 calories, 27 grams of carbohydrate and 1 gram of protein. It is fat-, cholesterol and sodium-free. Additionally bananas are:

  • Very high in vitamin B6 – 0.4 mg (22% of DRI)
  • High in dietary fiber – 3 gr in one medium banana ( DRI for women is 21-29 g women and 30-38 g for men)
  • High in manganese – 0.3 mg (16% of DRI)
  • High in potassium – 422 mg (12% of DRI)
  • High in vitamin C – 10.3 mg (17% of DRI)

They have a low glycemic index ranging from 42 in slightly unripe to GI 48 in over-ripe bananas. They also contain fructooligosaccharides, small amounts of the amino acid tryptophan and protease inhibitors.

What happens in your body after eating a banana?

The stomach


After eating a banana it travels from your mouth, through the esophagus to the stomach. With help of hydrochloric acid, enzymes and mucus the banana is converted into a thick soup (chyme) that can enter the small intestine. Although banana is a light food and isn’t digested by the stomach for too long it has beneficial effects for the health of your stomach:

  • Strengthens the stomach lining
    Research shows that banana thickens the mucus on the stomach walls and even promotes healing of ulcer lesions.
  • Protects stomach against ulcers
    Banana contains protease inhibitors which protect the stomach against ulcers.

The small intestine

Small intestines

Most of the magic of extracting all the health benefits from a banana happens in the small intestine. All nutrients are pulled out here and sent to the rest of the body with the help of specialized cells in the intestinal walls. While digested in the intestines, your body gets loads of benefits from this tasty fruit:

  • Protects your heart and blood vessels
    Bananas are high in potassium which benefits your heart health. Raising potassium intake and lowering sodium intake at the same time is crucial for your heart health and can protect against cardiovascular disease like stroke and heart attack. A study concluded that people who consumed 4,069 mg of potassium per day had a 37%  lower risk of death from cardiovascular disease than those on a low potassium diet. One medium banana has about 400 mg of potassium- so just keep on snacking on your bananas.
  • Strengthens the gut and immune system
    Bananas are a rich source of fructooligosaccharides. Fructooliogosaccharides are prebiotics that feed beneficial gut bacteria promoting a healthy gut flora. Gut bacteria are a vital part of our immune system and by giving them the right energy we enable our body to fight disease and maintain healthy intestines.
  • Effective antidepressant
    Feeling good after eating a banana is not only because of the sugar but because bananas contain tryptophan. Tryptophan is an amino-acid that is known as a mood-booster. In a study published in the Journal of Psychiatry and Neuroscience, tryptophan was found to significantly decreased quarrelsome behavior. Another way bananas keep you happy is with the help of vitamin B6. Bananas are rich in vitamin B6 which is used to help increase levels of serotonin in the brain.
  • Long term energy source
    Compared to grains and starches carbohydrates in bananas are easily broken down and used by the body for energy. Since the carbs in banana come with a bunch of fiber there is no immediate bloodsugar spike but the energy is slowly released over time which makes bananas a great food for athletes and before work out.
  • Rich source of vitamin B6
    One medium banana contains about 22% of the DRI of vitamin B6. This vitamin from the vitamin B complex family is vital in many process. It protects brain health, builds neurotransmitters, prevents anemia and coronary artery disease and can regulate blood glucose levels. Vitamin B6 is a water soluble vitamin, which means humans can’t store it. We have to take it in through food and bananas are an excellent source.
  • Eases digestion
    Banana is one of the most easily digested foods. It doesn’t put any strain on the digestive system – that way your body doesn’t have to allocate additional energy just for digestion. The energy a banana gives can be used by the body without great effort for healing and building processes.

The colon


After all the nutrients are pulled out of the banana the non digested parts enter the colon. Most of the matter that can’t be digested are fibers. Even these undigested parts of the banana have it’s benefits:

  • Insoluble fiber
    Most of the fiber in bananas is insoluble fiber that adds bulk to food making you feel full and helps passing of the stool. This fiber helps prevent constipation and is important for regular bowel movements.
  • Soluble fiber
    About 30% of the fibers in bananas are soluble. These fibers take in water and get a gel like consistency. They are important because they slow down the digestion preventing  spikes in blood sugar levels.

 Are bananas healthy or should you avoid them?

It is true that most of the calories in banana come from fructose, but the sugar in bananas is combined with a lot of fiber that prevents high blood sugar peeks like chocolate or other sweets cause. These fibers slow down the digestion releasing energy slowly over a longer period of time. That’s why you feel energized and full after eating a banana. Bananas are easily digested, rich in vitamins, minerals, antioxidants, fiber, flavonoids, fructooligosacharides and tryptophan. That’s why this sweet fruit is a perfect snack. It won’t bust your diet and you can enjoy it without guilt.

Photo credit: By Blausen Medical Communications, Inc. (Donated via OTRS)