Sugar in bananas, as with all fruits and vegetables, is a product of photosynthesis, or the conversion of light energy, water and carbon dioxide by a plant into an energy source that it can use. Plants release oxygen and use the sugars they create to fuel flower formation, growth and fruit development.
Fructose, glucose and sucrose are the most common types of sugar found in bananas. Even fully ripe, the sugar in bananas still has a fairly low glycemic index, which denotes how quickly a carbohydrate from a food enters the bloodstream. Bananas' high fiber and high content of resistant starch naturally mitigate spikes in blood sugar.
Bananas may merely taste sweeter than other fruits owing to relative amounts of simple sugars, fructose being roughly twice as sweet as glucose. However, the only difference between each type of simple sugar after it enters the human body concerns how the body processes it. The liver breaks down fructose, whereas glucose breaks down in the stomach.
The nutritional profile of bananas is exceptionally consistent because most bananas as something akin to natural clones. Growers simply replant root offshoots called "suckers," typically collected from the mother pseudostem. The result is little to no genetic variation between plantings.
"Banana" is a broad term encompassing some 50 species that thrive all over the world. Consumption stretches back thousands of years, and an early seedless mutation is the ancestor of the modern domesticated yellow banana. Bananas are non-seasonal, which means they grow year round; new generations peak in ripeness continuously.