Dietitian, Donna Van Zyl, explains the considerations for diabetes patients when eating fruit.

There is often concern as to eating ‘sweet fruit’ if you have diabetes. However, this does not mean that you should avoid eating fruit completely.

Fruit can be classified under the macronutrient, known as carbohydrates. Carbohydrates, or fruit, are digested and converted by the body into glucose and therefore should be counted as part of a carb-counting regimen.

What needs to be considered when eating fruit is: the type of fruit and the quantity consumed as both these influence blood glucose control.

If we look at the type, fruits are classified according to their glycaemic index, which will further have an impact on the spike of the blood glucose level.

Type of fruit: The glycaemic index

What is the glycaemic index (GI)?

It is a numerical measure of the rate i.e. how fast and to what extent the intake of carbohydrate rich foods may affect your blood glucose levels. An item of food with a high GI raises blood glucose levels more than an item of food with a medium or low GI.

Glucose has been given a numerical value of 100, because it is absorbed immediately into the bloodstream. All carbohydrate-containing food, such as fruit, are compared to the reference of glucose.

The low-GI index food items fall below the reference range of 40 (<40) and are given the green to go. Whereas intermediate-GI food items falls within the reference range of 56 – 69; the orange for slow down and proceed with caution. The high-GI food items, with a reference range of above 70 (70+), gets the red for halt.

Though, high-GI fruits can be consumed with exercise, depending on blood glucose levels, and in combination with other foods products, especially protein or fat, or even to correct a hypoglycaemic event.

The GI Foundation uses the following icons to indicate the GI of foods:

Absorption and digestion factors

Factors affecting the absorption and digestion of fruit, which in turn may influence the GI of foods include:

• The amount of cooking (cooked apple versus raw apple).
• Processing (fruit versus fruit juice).
• Ripeness and storage time: the riper a fruit, the higher the GI.
• The type of fibre (soluble – citrus fruits).
• The more acidic a food is, the lower the GI value. e.g. lemon juice lowers the GI of the food or meal.
• The presence of fat, protein or low-GI foods consumed with the GI carbohydrate.

When eating a higher GI fruit, you can combine it with other low GI foods, or protein and fat to balance out the effect on blood glucose levels. For example, eating a fruit salad and yoghurt (plain).

The GI of fruit commonly eaten

When looking at the GI of specific fruits above, a variety of low GI fruit should form part of a balanced dietary intake. Fruits are not only delicious, but a good source of fibre which helps aid in regulating blood glucose levels. Fruits are also a good source vitamins, minerals or phytochemicals which aid bodily functions and help fight against disease.

Give preference to apples, berries, peaches or citrus throughout the day and consume with meals to ensure that the rise in blood glucose is covered by the insulin injected i.e. part of carb-counting.

Whereas your high-GI fruit, such as watermelon or grapes, can be used to prevent hypoglycaemia, especially after exercise, or to correct a hypoglycaemic event.

Quantity

Be mindful of your portions too. You will see the above-mentioned GI of fruit is indicated per quantity. Remember, the more fruit you eat at once, the more fruit sugar is also consumed which will affect blood glucose control.

One small apple provides approximately 15g of glycaemic carbohydrates. So, eating two apples in one go will naturally provide you with up to 30g of glycaemic carbohydrates, which will lead to a spike in blood glucose levels due to quantity consumed.

Take home message

Fruits form part of a healthy balanced intake. A variety of low-GI fruit should ideally be consumed and distributed throughout the day. Be cautious with high-GI fruits, however. they can be useful especially in picking up blood glucose levels.

MEET OUR EXPERT

Donna van Zyl is a private practicing dietitian for Nutritional Solutions, Bloemfontein. She is growing in the field of paediatrics and plays a key role in individualising nutritional therapy for Type 1 diabetics. Her special interest is in optimising health, managing chronic lifestyle related diseases, and sports nutrition. She lectures part-time at the University of the Free State, which she enjoys thoroughly.