ABSTRACTS: Oral Presentation Abstracts
Introduction: Dietary carbohydrates are digested and absorbed at different rates and amounts depending on the food sources and their origins. Rapidly and highly elevated blood glucose levels postprandially may be detrimental to health (type 2 diabetes, obesity). Diets rich in slowly digested carbohydrates may protect against chronic diseases. Altering the quality of carbohydrates in diets of young children may exert important health implications. This study determines the quantity of glucose released from carbohydrate mixtures, expressed as the available glucose portion (AG). Distinction is made between rapidly (RAG) and slowly available glucose portions (SAG).
Methods: The in-vitro dynamic-digestive-dialysis-model (1) was adapted to measure glucose availability from cereals. 9.5 g of carbohydrate mixture was added to 100 ml milk. Sample A contains rice flour (31.7%), tapioca (31.1%), sucrose and maize starch (13.5%). Sample B is composed of rice flour (37.5%), maltodextrose, tapioca (28.8%) and maize starch, no sucrose is added. Sample C is made of wheat flour (95.2 %), rice flour (1.1 %), rye flour, maize starch (1.1%) and sucrose. Samples were treated to determine free soluble glucose (FSG = free Glc + Glc from sucrose) and total glucose (TG). Glucose concentrations were analysed spectrophotometrically. Total starch (TS) was calculated by multiplying TG by factor 0.9.
Results: The method yields CVs of 0.73 % intra-assay and 16.5 % inter-assay for measurement of the AG. Sample A contains high FSG (148 ±3 mg/g), which corresponds to the high RAG fraction (34.8 ±7.5 mg/g). SAG and total AG are 94.9 mg/g (±15.3) and 130 mg/g (±17). TG and TS are 0.86 g/g (±0.06) and 0.64 g/g (±0.0). Sample B contains low FSG (4.9 ±1.2 mg/g) and low RAG (15.9 ± 4.8mg/g) due to the lack of added sugars. SAG is relatively high (80.6 ±16.3 mg/g) compared to the total amount of AG (96.5 ±19.6 mg/g). TG and TS are 1.00 g/g (±0.03) and 0.9 g/g (±0.00). FSG of sample C is 65.8 mg/g (± 0.3) with relatively low RAG (15.6 ± 3.7 mg/g). SAG is also low (45.7 ± 12.6 mg/g) due to the relatively low total AG of the high cereal mixture (61.2 ± 13.0 mg/g). TG and TS are 0.81 g/g (±0.07) and 0.67 g/g (± 0.00).
Conclusion: Carbohydrate mixtures of different composition (quality and quantity) exert different effects on the amount of available glucose thereby influencing the portions of rapid or slowly available glucose. Added sugars increase the rapid available glucose portion, whereas dietary fibres may decrease overall glucose availability with special attention to the lowering effects on the rapid available glucose fraction.
D Bosscher, M Van Caillie-Bertrand, K Van Dyck, H Robberecht, R Van Cauwenbergh, H Deelstra. 2000. J Pediatr Gastroenterol Nutr. 30:373–8.