Just last week an elderly gentleman sat across my table lamenting his high blood glucose values. “I have always been well controlled. But over the last three months, my sugars have shot up. I am very careful with my lifestyle. There is only one change I have made in my diet. I have replaced two meals with fruits. This has increased my consumption of fruit. They are the healthiest, most natural foods one can have. They can’t raise my sugar, can they?”
What is the correct answer to my patient’s question? Fruits are said to be nature’s candy, full of sweetness. Most of us love fruits because they look and taste good and we (rightly!) feel that they are good for our health. Fruits are an important part of our diet since they are packed with numerous vitamins, minerals and antioxidants like polyphenolic flavonoids, vitamin C and anthocyanins. These compounds not only protect the human body from the oxidative stress of free radicals but also boost the immunity level of the body.
Many fruits are rich in fibre, which plays an important role in managing our sugar levels. A diet high in soluble fibre slows sugar absorption. Besides, fibre makes us feel full, so we eat less. Fruits have a lot of water, which improves hydration. Both fibre and water in the fruit help in battling constipation, a common problem in people with diabetes. Diets which contain adequate amounts of vegetables and fruits reduce the risk of obesity, high blood pressure, heart attack, stroke and cancer.
So, can people with diabetes consume fruits liberally? Or, because of their inherent sweetness, are fruits a strict no-no in diabetes? The truth, as usual, lies somewhere in between. First, any fruit can be consumed by a person with diabetes. Second, not all fruits are the same, and the recommended portion sizes vary a lot based on the glycaemic index (GI). The GI is a rating of foods on a scale from 1 to 100. The higher the score, the faster the absorption and the consequent rise in blood sugar. Third, the most beneficial effects of fruits are seen only with fresh fruits and not with canned or processed fruits, many of which contain added sugar, and may be depleted of nutrients. Fourth, fruit juices are not the same as fruits. In fact, they contain just the sugary part of the fruit without the fibre, are much less nutritious and send the blood sugar spiking.
Which fruit and how much is advisable for people with diabetes? The key to fruit consumption in diabetes is incorporating them into the daily carbohydrate allowance. So if you are going to add fruits to your diet, you will have to cut back on other carbohydrates. The amount of carbohydrate present in the fruit determines the impact on blood sugar level. For people with diabetes, one serving of fruit should contain 15 grams of carbohydrates and the total daily intake should not exceed 30 gm. So one can have a 15 gm carb serving of fruit in one sitting, and a total of two fruit servings in a day. Eating fruits as a snack consumed mid-morning or mid-evening is preferable to having them as dessert after meals since they add to the carbohydrate load. Rather than consuming large portion sizes of fruits, it is best to combine them with protein-rich foods like dairy products or nuts. Since fruits lack proteins, this makes the snack more nutritious and filling.
The glycaemic index also helps us choose our fruit, because it reflects the speed of rise in blood glucose. Examples of low GI fruits (GI 20-49) include apples, avocados, cherries, guava, peaches, pears, and strawberries. Medium GI fruits (GI 50-69) include figs, grapes and oranges. Fully ripe bananas and dates are examples of high GI fruits. Portion sizes of different fruits that provide 15 gm carbs are shown in the table.