Effects of a medical food containing an herbal alpha-glucosidase inhibitor on postprandial glycemia and insulinemia in healthy adults

J Am Diet Assoc. 2005 Jan;105(1):65-71. doi: 10.1016/j.jada.2004.11.001.


Objective: To determine the effect of different doses of Salacia oblonga extract, an herbal alpha-glucosidase inhibitor, on postprandial glycemic, insulinemic, and breath hydrogen responses in healthy adults.

Design: Double-masked, randomized crossover design.

Intervention: Subjects, after fasting for 12 hours, consumed four test meals consisting of 480 mL of study beverage (14 g fat, 82 g carbohydrate, and 20 g protein) with 0, 500, 700, or 1,000 mg of S oblonga extract on four separate occasions. Capillary finger-prick plasma glucose and venous serum insulin concentrations were measured at baseline and for 2 hours postprandially. Breath hydrogen excretion was measured at baseline and hourly for 8 hours postprandially.

Subjects/setting: Thirty-nine healthy, nondiabetic adults (body mass index=23.7+/-0.4, age=25.7+/-0.9 years.

Statistical analyses performed: Repeated-measures analysis of variance was applied to the raw data or data that had been transformed (log, rank) when necessary due to nonnormality. The Tukey-Kramer post hoc test was used for pairwise comparisons.

Results: Compared with the control, the 1,000-mg S oblonga extract dose reduced the plasma glucose and serum insulin incremental areas under the curve (0 to 120 minutes postprandial) by 23% ( P =.32) and 29% ( P =.01), respectively. The other doses of S oblonga extract did not impact glycemia or insulinemia. Breath hydrogen excretion increased linearly as the dose of S oblonga extract was advanced.

Conclusions: The presence of S oblonga extract tended to lower postprandial glycemia and significantly reduced the postprandial insulin response. The increase in breath hydrogen excretion suggests a mechanism similar to prescription alpha-glucosidase inhibitors. Future studies of S oblonga extract in patients with diabetes are needed.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Area Under Curve
  • Beverages
  • Blood Glucose / metabolism*
  • Breath Tests
  • Celastraceae / chemistry*
  • Cross-Over Studies
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Enzyme Inhibitors / metabolism*
  • Female
  • Glucose Tolerance Test
  • Glycemic Index
  • Glycoside Hydrolase Inhibitors*
  • Humans
  • Hypoglycemic Agents / therapeutic use*
  • Insulin / blood*
  • Male
  • Plant Extracts / therapeutic use*
  • Postprandial Period
  • alpha-Glucosidases / metabolism


  • Blood Glucose
  • Enzyme Inhibitors
  • Glycoside Hydrolase Inhibitors
  • Hypoglycemic Agents
  • Insulin
  • Plant Extracts
  • alpha-Glucosidases