Glycaemic Indices of the Traditional Sago-Based Snack and Staple Food in Sarawak, Malaysia

Abstract

Sago (Metroxylon sagu) starch was the staple carbohydrate source in Sarawak, Malaysia. Saguk and Linut are two well-known traditional Sago foods. Like many traditional Sago foods, their glycaemic index (GI) has yet to be established. This study aimed to determine the GI for Saguk and Linut. Isoglucidic servings containing 50g available carbohydrate for both foods and glucose drink as reference, were consumed by 12 healthy subjects. Blood was drawn at predefined intervals for 2 hours to measure postprandial glycaemia and subsequently to determine the GIs. Linut and Saguk demonstrated “moderate to high GI” and “moderate to low GI” values of 69.8 ± 5.5 and 46.9 ± 5.1. In addition, glycaemic load (GL) at various serving sizes was also evaluated. Serving sizes illustrated as one quarter, half and three quarters of a regular rice bowl, yielded “low to high” GLs values from 10.0 to 27.4 for Linut, while “low to moderate” GLs values from 5.9 to 17.6 for Saguk. Albeit its high GI, the GL for Linut at a serving size of up to half the volume of a regular rice bowl was moderate, thus suggesting a healthier serving Linut indulgence. This visualization is thought to be useful as portion control for Linut. This low GI characteristic of Sago is believed to be attributed to its resistant starch (RS) content. The marked GI difference between Saguk and Linut was the result of "wet" and "dry" heat treatments, which has profoundly affected the starch structure resulting in loss of RS, thus increasing starch digestibility. It is therefore noteworthy to exercise caution and refrain from any generalisation that meals composed predominantly from high RS sources such as Sago starch would elicit low glycaemic response. This can lead to erroneous deduction if factors such as food processing and glycaemic burden per serving are not judiciously considered.