Do Overripe Bananas Still Have Nutritional Value?

All fruits start to lose their nutritional value as soon as you pick them, according to registered dietitian Sandra Bastin, Ph.D., of the University of Kentucky Cooperative Extension Service. While overripe bananas certainly have nutritional value, they lose some benefits and gain others if you eat them at this stage. Processors pick bananas when they're still hard and unripe so they survive the trip to the store without splitting.

Calories

Bananas have a higher calorie count than many other fruits due to their high sugar levels. As a banana ripens, its nutritional content may change, but the calorie count remains the same, about 105 calories for a medium-sized banana 7 to 8 inches long. The carbohydrate makeup changes as the banana ripens, but since all carbohydrates contain 4 calories per g, the total calorie count remains the same.

Sugars

An unripe banana contains mostly starch, a complex carbohydrate. As the banana ripens, the starches change to simple sugars. Simple sugars are easier to digest and may raise your blood glucose levels more quickly, which could be a factor if you have diabetes. A ripe banana tastes sweeter because of the change in carbohydrate composition. Around 40 percent of the carbohydrate in a yellow-green banana consists of starch, compared with only 8 percent in a ripe banana, whose carbohydrate content consists of 91 percent simple sugars, author Carol Ann Rinzler explains in "The New Complete Book of Food: A Nutritional, Medical, and Culinary Guide." Because unripe bananas contain an enzyme that inhibits starch breakdown, ripe bananas are easier to digest.

Micronutrients

Micronutrients, which include vitamins and minerals, may decrease as bananas ripen. Vitamin C content in particular as well as water-soluble vitamins folic acid and thiamin tend to decline as fruits age, especially if you cook them. Once bananas ripen fully, store them in the refrigerator to minimize further vitamin loss.

Antioxidants

Bananas, like most fruits and vegetables, contain antioxidants, plant substances that help keep cell DNA healthy by destroying free radicals, molecules that damage cell DNA and can cause heart disease and cancer. As a banana ripens, the antioxidant content increases, David L. Katz, M.D., explains in the June 2009 issue of "O, The Oprah Magazine." Researchers from the University of Innsbruck reported in the 2007 issue of "Angewandte Chemie" that ripe fruit contains nonfluorescing chlorophyll catabolytes, or NCCs, highly active antioxidants.