Attenuation of postprandial glycemia is hypothesized to reduce the risk of progression from impaired glucose tolerance to diabetes. It is also thought to reduce the number of complications associated with diabetes. S. oblonga extract has been shown to reduce postprandial glycemia when it is fed in addition to a liquid nutritional supplement containing mainly maltodextrin. No studies have been done, however, using S. oblonga extract on a solid meal. The purpose of this study was to measure the effects of S. oblonga extract on the postprandial glycemic and lactate responses along with the perceived gastrointestinal, satiety, and flatulence symptoms severity following a solid, high starch meal. Fourteen subjects (8 males, 6 females) ate two test meals after an overnight fast following a standardized dinner.
The meals consisted of 112 g durum spaghetti noodles, one cup (8 oz.) of Meijer meatless spaghetti sauce, and one cup (8 oz.) of unsweetened, caffeine-free tea. In the treatment meal, the tea also contained 480 mg of S. oblonga extract. The subjects had their glycemic responses to the meals measured through two hours postprandial. The subjects then ate a standardized lunch and reported perceived satiety, gastrointestinal distress, and frequency of flatulence while fasting for an additional five hours. The serum glucose positive incremental area under the curve (AUC) response was reduced by 25% (P = 0.022) and the serum lactate AUC response was reduced by 29% (P = 0.033) in the treatment meal compared with the control meal. The serum glucose baseline-adjusted peak was reduced by 27% (P < 0.001) and the serum glucose excursion was reduced by 23% (P = 0.002) in the treatment meal compared with the control meal. Also, the total number of gas passages for hours 0-8 increased from 7.29 ± 1.76 in the control to 26.4 ± 4.59 in the treatment (P = 0.001) indicating the alpha-glucosidase inhibitory effects of S. oblonga. In summary, S. oblonga extract effectively lowered the postprandial glucose response to a high starch meal, consistent with previous studies on this herb.
The extract may have value in the management of blood glucose for persons with diabetes. The development of mild to moderate flatulence is a limitation for the use of this herbal extract. More studies are needed to develop ways to improve gastrointestinal tolerance.