A convenient and nutritious snack, bananas supply potassium, magnesium and B vitamins. Although the banana's sweetness may lead you to assume this fruit raises blood glucose quickly, in reality its effect on blood glucose doesn't differ much from other fruits. The banana's relatively high fiber content is one reason for its moderate effect on blood sugar. Fiber slows carbohydrate breakdown, resulting in a slower increase in blood glucose.
Glycemic Index
The glycemic index, or GI, rates how quickly a food raises your blood glucose, or blood sugar, level. With a GI of around 51 to 54, bananas are a low- to medium-GI food. Ripe bananas have a higher GI than unripe ones. This means bananas do raise your blood glucose levels, but not very quickly. Because of this moderate rise in blood sugar, bananas aren't likely to cause an insulin spike that could result in hypoglycemia, or low blood sugar, shortly after eating.
Diabetes Fruit Exchanges
Because bananas are rich in carbohydrates, which raise blood sugar more quickly than protein or fat, just on 3-inch piece of banana counts as a fruit exchange in the Diabetes Exchange System. Like all fruit exchanges, this amount of banana contains around 15g of carbohydrates. All fruit exchanges have a similar effect on your blood sugar. A 1-cup serving of raspberries or cubed cantaloupe, which both count as fruit exchanges, affects your blood sugar as much as a 3-inch piece of banana.
Treating Hypoglycemia
The banana's ability to raise blood glucose moderately is helpful if you have diabetes and experience hypoglycemia. If your blood sugar falls below 70mg/dl, you'll need a source of quickly absorbed glucose, such as 1/2 cup orange juice or two to four pieces of hard candy, explain experts from the University of Illinois. Once your blood sugar is within a normal range, however, you'll still need to eat a balanced meal or snack if your next scheduled meal is more than an hour away. A small banana and 1 oz. low-fat cheese is one snack option.
Keeping Your Blood Sugar Stable
Even if you don't have diabetes, keeping your blood sugar stable helps you maintain your energy levels. Although eating a banana won't cause a dramatic rise in blood sugar, this fruit alone doesn't provide long-lasting energy. Combining bananas with a low-fat protein source and a high-fiber food allows for a more gradual fall in blood sugar after eating, which keeps your energy up longer. For an energy-sustaining snack or small meal, try a banana along with nuts or poultry for lean protein and whole grain bread or oatmeal for fiber.
References
- Harvard Medical School: Harvard Health Publications: Glycemic Index and Glycemic Load For 100+ Foods
- University of California Davis Health System: Chronic Disease Management: Diabetes Nutrition: Exchanges
- University of Illinois at Urbana-Champaign: McKinley Health Center: Diabetes and Low Blood Glucose
- Rutgers University; Monthly Health Message: Small Steps to Improve Blood Sugar; Karen Ensle; February 2007
- New York University Langone Medical Center; What Is the Glycemic Index?; Sarah J. Kerr; May 2011
- USDA Nutrient Database: Bananas, Raw
