Low-dose acarbose does not delay digestion of starch but reduces its bioavailability.
OBJECTIVE
Slowly digestible starch is associated with beneficial health effects. The glucose-lowering drug acarbose has the potential to retard starch digestion since it inhibits alpha-amylase and alpha-glucosidases. We tested the hypothesis that a low dose of acarbose delays the rate of digestion of rapidly digestible starch without reducing its bioavailability and thereby increasing resistant starch flux into the colon.


METHODS
In a crossover study, seven healthy males ingested corn pasta (50.3 g dry weight), naturally enriched with (13)C, with and without 12.5 mg acarbose. Plasma glucose and insulin concentrations, and (13)CO(2) and hydrogen excretion in breath were monitored for 6 h after ingestion of the test meals. Using a primed continuous infusion of D-[6,6-(2)H(2)] glucose, the rate of appearance of starch-derived glucose was estimated, reflecting intestinal glucose absorption.


RESULTS
Areas under the 2-h postprandial curves of plasma glucose and insulin concentrations were significantly decreased by acarbose (-58.1 +/- 8.2% and -72.7 +/- 7.4%, respectively). Acarbose reduced the overall 6-h appearance of exogenous glucose (bioavailability) by 22 +/- 7% (mean +/-se) and the 6-h cumulative (13)CO(2) excretion by 30 +/- 6%.


CONCLUSIONS
These data show that in healthy volunteers a low dose of 12.5 mg acarbose decreases the appearance of starch-derived glucose substantially. Reduced bioavailability seems to contribute to this decrease to a greater extent than delay of digestion. This implies that the treatment effect of acarbose could in part be ascribed to the metabolic effects of colonic starch fermentation.
Wachters-Hagedoorn
R E
RE
Department of Paediatrics and Department of Medical Biomics, University of Groningen Medical Centre, Groningen, The Netherlands.
Priebe
M G
MG
Heimweg
J A J
JA
Heiner
A M
AM
Elzinga
H
H
Stellaard
F
F
Vonk
R J
RJ
D020909:Acarbose / Q000493:pharmacokinetics*; D000328:Adult; D001682:Biological Availability; D001786:Blood Glucose / Q000032:analysis*; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D018592:Cross-Over Studies; D004063:Digestion / Q000187:drug effects; D006801:Humans; D006859:Hydrogen / Q000032:analysis; D007004:Hypoglycemic Agents / Q000493:pharmacokinetics*; D007328:Insulin / Q000097:blood*; D008297:Male; D019518:Postprandial Period; D013213:Starch / Q000378:metabolism*
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D002245:Carbon Dioxide; D006859:Hydrogen; D013213:Starch; D020909:Acarbose