Little is known about the effect of dietary fiber on gastric emptying. At present, we do not know whether any therapeutic effects result from delayed gastric transit time. Functional scintigraphy was used to determine the effect of wheat bran, guar and pectin on the transit time of 200 ml fruit juice and 200 or 400 ml of a liquid test meal in normal healthy subjects. The transit time of fruit juice was significantly delayed by the addition of 4 g guar (viscosity 7079 mPA X s). Neither wheat bran, pectin nor guar resulted in a delay of the test meal transit time despite maximal increases in viscosity of up to 21,500 mPa X s. We therefore conclude that dietary fiber does not significantly delay the gastric transit time of test meals regardless of the increase in viscosity. The reduction in postprandial glucose levels after ingestion of guar or pectin is, therefore, probably not due to delayed gastric emptying.