The blood glucose response to feeding whole and fiber-depleted cereals and cereal products was studied in healthy volunteers. No difference was seen between white and wholemeal bread and spaghetti or between white and brown rice. This lack of effect of cereal fiber on postprandial blood glucose levels suggests that the reported beneficial long-term effects of cereal-based, “natural,” high fiber diets on diabetic control must be due to other aspects of the diet or to a different effect of fiber.