Do Different Fractions of Digestible Carbohydrates in Foods Influence the Glycaemic Responses?

The Glycaemic Index (GI) concept ranks foods according to the postprandial glycaemic responses. The in vivo procedure used to determine GI values of food is very laborious and time consuming. Thus, the aim of this study was to analyze the in vitro rate of release of glucose from foods of Sri Lankan origin with the intention of identifying the relationships of the in vitro data with the published in vivo glycaemic responses. The fractions of glucose released and starch hydrolyzed in the in vitro method were classified as rapidly available glucose (RAG), slowly available glucose (SAG), rapidly digestible starch (RDS) and slowly digestible starch (SDS) depending on the time taken for digestion and release of glucose. Basic foods (n=15) prepared with wet and dry heat process were analyzed to determine above fractions. The glucose released from basic foods were then used to calculate the RAG, RDS, SAG, and SDS fractions present in the mixed meals (n=2) containing more than one carbohydrate source. Significant positive correlations were observed with GI and RAG (r=0.513, p=0.025), RDS (r=0.597, p=0.011) and significant negative correlation with SAG/RAG (r=-0.511, p=0.036) ratio of both basic foods and mixed meals. The foods with high GI contain a higher percentage of carbohydrates in a form that can be rapidly hydrolyzed to yield glucose and correspondingly increased postprandial glucose levels.