Does Fruit Make Your Blood Sugar Go Up?
Carbohydrates are your body's most important source of energy. Fruit is one of the healthiest sources of carbohydrates, providing you with many vitamins and minerals. But most fruits contain sugar that can raise your blood sugar and increase the demand for insulin from your pancreas. Choosing certain fruits over others and managing portion size can limit this effect and help keep you healthy.
Fruits can and will make your blood sugars rise, but you can manage their impact by choosing fruits with a low glycemic index or reducing portion size.
All carbohydrate-based foods contain sugar in some form, either as simple sugars such as fructose, found in fruit, or as complex molecules such as starch, which is made up of chains of sugar molecules. When your body digests carbohydrate, it converts it into glucose, a simple but important sugar that travels in your blood to reach all your cells. Your cells use glucose as an energy source, and certain types such as brain cells depend on it exclusively. But when your blood sugar increases quickly and reaches high levels, this puts a major demand on your pancreas to release insulin, the hormone that lowers blood sugar. Over time, frequent episodes of high blood sugar can raise your risk of Type 2 diabetes.
Fruit and the Glycemic Index
The glycemic index classifies foods by how quickly they raise blood sugar and to what extent. Because most fruits are sweet and contain simple sugar, or fructose, you might expect that they all raise blood sugar rapidly and dramatically, and that every type of fruit has a high glycemic index. But this is not always the case, according to the American Diabetes Association, which says that high-fiber fruit tends to have a lower glycemic index. This is because dietary fiber slows uptake of glucose produced by digestion of carbohydrate, an effect that can significantly lessen the impact of sugar in fruit on your blood glucose.
The Dietary Guidelines for Americans identify fruit as one of the foods that Americans routinely under-consume. The Guidelines recommend you consume 2 cups of fruits daily if you take in a total of about 2,000 calories every day. By paying attention to the glycemic index, you can make choices that minimize the impact of fruit on your blood sugar, aiming for those that are rich in fiber. High-fiber fruits tend to have a glycemic index under 55, a value considered to be low. Examples of fruit with a low glycemic index include apples, citrus fruits such as grapefruit or oranges, peaches and berries such as strawberries and raspberries. Fruit with a relatively high index include ripe bananas, grapes, raisins and watermelon.
Controlling Serving Size
In addition to choosing fruits with a generally low glycemic index, you can also lessen the impact of fruit on your blood sugar by controlling the size of your portions. Ideally one serving of fresh fruit should contain no more than 15 grams of carbohydrate. Following this strategy, you might choose a larger serving of a fruit that is less sweet or a smaller serving of a fruit that contains lots of sugar. Examples of fruit servings with about 15 grams of carbohydrate include 1 1/4 cup of whole strawberries, 3/4 cup cubed pineapple and 1/2 of a medium banana.
- MedlinePlus: Carbohydrates
- Harvard T.H. Chan School of Public Health: Carbohydrates and Blood Sugar
- MayoClinic.com: Diabetes Diet: Should I Avoid Sweet Fruits?
- Centers for Disease Control and Prevention: More About Carbs
- Harvard Medical School: Glycemic Index and Glycemic Load for 100+ Foods
- MayoClinic.com: Glycemic Index Diet: What's Behind the Claims
- The University of Sydney: The Glycemic Index
- Dietary Guidelines for Americans, 2015-2020: Executive Summary
Joanne Marie began writing professionally in 1981. Her work has appeared in health, medical and scientific publications such as Endocrinology and Journal of Cell Biology. She has also published in hobbyist offerings such as The Hobstarand The Bagpiper. Marie is a certified master gardener and has a Ph.D. in anatomy from Temple University School of Medicine.