Bananas are one of the most widely consumed fruits in the world, and are rich in fiber and other vital nutrients that contribute to a healthy diet.
Originating in Southeast Asia, bananas grow in warm climates and belong to a family of plants called musa. Technically a berry, these fruits can have skins of various colors, from purple and red to brown, green and yellow.
Yellow bananas are the most common variety sold commercially, and when these get very ripe, they turn brown or black.
Plantains are a type of banana considered a dessert fruit, and are usually served cooked; these are generally quite firm and contain a larger amount of starch than bananas peeled and eaten raw.
Because raw bananas are readily available, reasonably priced, and easy to take along, they are a great choice for including regularly in the diet.
Bananas come in all sizes, from miniature to large, and one medium banana averages about a hundred calories. They are low in both protein and fat content, and rich in fiber.
Bananas are a good source of potassium, which helps maintain optimal kidney function. Eating foods high in potassium has been shown to lower blood pressure, which can have a beneficial effect on cardiovascular health. (1)
A single banana delivers nearly a tenth of the RDA for potassium, 8% of the magnesium requirement, more than a quarter of the RDA for vitamin B6, as well as 10% of the vitamin C we need daily. (2)
Magnesium is necessary for a wide range of processes in the body, and many people don’t get enough of this mineral. Adequate magnesium levels are associated with protection against many chronic disorders, including heart disease, type 2 diabetes, and high blood pressure. (3, 4)
This vital mineral also plays a role in preserving bone density in the aging process. (5)
You’ll also get smaller amounts of these vitamins and minerals by including bananas in your diet: manganese, copper, folate, choline, vitamins B1, B2, B3 and B4.
The Sugar/Carbohydrate Question
The main macronutrient found in bananas is carbohydrate, just like most other fruits. The nature of the carbs changes during ripening.
Starch content of unripe bananas runs between 70 and 80%; during the ripening process, starch content decreases to less than 1% as it is transformed into sugars. The sugars in bananas are fructose, sucrose and glucose, and when the fruit is ripe, sugars can account for up to 16% of weight. (6)
The glycemic index of bananas is on the low side, ranging between 42 and 58 depending on the ripeness. (7) Foods with lower glycemic index ratings don’t cause as much of a spike to blood sugar levels, making bananas a good choice for carbohydrates, especially when compared with carbs derived from refined foods like white flour and sugar.
Bananas don’t hit the bloodstream hard because fiber content is high. The resistant starch in unripe bananas passes through the stomach, and is fermented in the large intestine by friendly bacteria.
This process results in the formation of a short-chain fatty acid called butyrate, which can improve intestinal health. (8)
Eating foods containing resistant starch is associated with numerous health benefits, including lower blood sugar levels following meals, a decrease in insulin resistance, greater feelings of satisfaction after eating, and better colon health. (9, 10, 11, 12, 13)
Like other fruits, bananas also contain pectin, another type of fiber. Some of the pectin is water-soluble, and accounts for the softening of bananas as they ripen. (14)
Both pectin and resistant starch play a role in softening the effect of the carbohydrates on blood sugar. Pectin can also work to decrease appetite by helping you feel more satiated, and may cut the risk of developing colon cancer. (15, 16)
When obese diabetic patients took 24 grams of banana starch daily for a month, average weight loss was just over two and a half pounds; insulin sensitivity also improved. (17)
Bananas are not among the fruits usually considered weight-loss friendly since a medium banana contains 27 carbs. But if your weight-loss plan doesn’t require low carbohydrate intake, other beneficial qualities of this fruit, especially the resistant starch content, may make it worth spending the carbs.
Benefits of Plant Compounds
Bioactive substances found in fruits and vegetables are extremely beneficial to health, and bananas have certain unique properties.
Several antioxidant flavonoids are present in bananas, including catechins, which have been associated with improved heart health. (18)
While bananas contain dopamine, a brain neurotransmitter, in this case the substance does not cross the blood-brain barrier. This means that it won’t affect your mood; instead, the dopamine in bananas acts as an antioxidant. (19)
Antioxidants are vital for creating and maintaining good health: they neutralize free radicals in the body and help prevent oxidative damage. Keeping free radicals and antioxidants in the proper balance is important. (20, 21)
Bananas and other fruits, along with vegetables, are the best sources of dietary antioxidants.
The Down Side
On the whole, bananas are a very nutritious food that many people find effortless to include in a healthy diet.
If you’re allergic to latex, you might find bananas don’t work for you either.
Interestingly, between 30% and 50% of people who have sensitivities to natural rubber latex also have allergies to plant foods, the most common of which are potato, bell pepper, tomato, chestnut, kiwi, avocado and banana. (22)
Diabetics should be careful with bananas despite the low glycemic index rating, although moderate amounts should not pose a problem; monitoring blood sugar levels when consuming large quantities of any food rich in sugar or carbohydrates is the best idea.
Some may have concerns about the ethylene used in ripening rooms for various types of produce, including bananas, but it is actually a natural plant hormone and is Generally Recognized As Safe (GRAS).
Fruits and vegetables produce ethylene in response to aging and injury, such as bruising or nicks to the skin, which can occur during handling.
The concentrations of ethylene found in ripening rooms (100 to 150 parts per million) have not been found to be toxic; this process is also used to trigger ripening in many other fruits and vegetables, including tomatoes, apples, peaches, avocados. (23)
Summary: Bananas are a good source of antioxidants, potassium, fiber and other nutrients that play important roles in various body functions; a banana a day may be just as good at keeping the doctor away as any other fruit.