A Study of Blood Glucose Response Following Temperate and Tropical Fruit Ingestion in Healthy Adults

Fruits are well known to have high nutritional values. However, the response in blood glucose level varies with different fruits. To date, data has not been compiled to rank local fruits according to their blood glucose response. Therefore, this randomised experimental study was carried out to determine the blood glucose response after consuming ten types of tropical fruits (mango, rambutan, longan, sapodilla, jackfruit, watermelon, papaya and banana of three varieties, brangan, rastali and mas) and four types of temperate fruits (red apple, orange, grape and green pear). A total of 72 healthy subjects randomly divided into groups of 12 to 20 subjects (mean age: 21.5+0.6 years, mean BMI: 21.13+1.49 kgm-2) were requested to consume test fruits or reference food (glucose) after an overnight fasting on separate occasions. Each test fruit and the glucose contained 50g of carbohydrates. Finger-prick blood samples were obtained at 0 (fasting), 15, 30 60, 90 and 120 min after consuming each fruit. The blood glucose response was obtained by calculating area under the curve (AUC). The AUC ranged between 57.59+10 mmol.min/L and 313.2 mmol.min/L, with glucose showing the highest AUC (p<0.05) compared to all fruits tested. Banana gives the highest blood glucose response while green pear showed the lowest. The fruits ranked in descending order based on the AUC values were longan, followed by rambutan, grapes, watermelon, orange, papaya, jackfruit, sapodilla, mango and red apple. Tropical fruits had significantly higher AUC than temperate fruits (p<0.05). Overall, bananas demonstrated the largest rise in postprandial blood glucose response (62%) when compared to glucose while green pear showed the lowest response (18%). This preliminary data could be used as a recommendation to diabetic patients for optimum blood glucose control. ____________________ Correspondence author: Barakatun Nisak Mohd Yusof, email: [email protected] glucose response known as glycaemic index (Jenkins et al., 1981). Foods that contain carbohydrate are digested and absorbed at a slower rate, resulting in lower blood glucose. Hence, these foods may have metabolic benefits in relation to diabetic control (Ludwig, 2000). However, little attention has been given to fruits (Guevarra & Panlasigui, 2000). Fruits consist mainly of carbohydrates and are known to have high nutritional values specifically in terms of micronutrients (Fatema et al., 2003). Nevertheless, the compositions vary greatly (Hoover-Plow, Savesky & Dailey, 1987). Studies have shown that high intake of fruits and vegetables may have a protective effect against cardiovascular disease (CVD) (Liu et al., 2000) and decrease the risk of developing diabetes (Ford & Mokdad, 2001). The type and amount of fruits to be included in daily diets of diabetics has always been a concern (Guevarra & Panlasigui, 2000). Fatema et al. (2003) has reported that it is important to know the composition of fruits and their biological responses in order to rationalise the advice of including fruits in the diet of diabetic patients. In addition, Brand-Miller, Olagiuri & Foster-Powell (1997) have documented that tropical fruits may produce higher responses of postprandial blood glucose than temperate fruits. Therefore, the objectives of this study are to determine the blood glucose response for some tropical and temperate fruits in healthy adults compared to glucose itself. This novel data could be used by dietitians and nutritionists in recommending the most suitable fruits for patients, especially individuals with diabetes.