Degree of habitual mastication seems to contribute to interindividual variations in the glycemic response to rice but not to spaghetti.

Previous work by our group showed that the degree of particle breakdown of rice during mastication affects in vitro glycemic potency. The objective of this study was to confirm these in vitro findings in an in vivo model. We hypothesized that the degree of habitual mastication will influence individuals' in vivo blood glucose response (glycemic response, or GR) to carbohydrate foods. Eleven participants came in on six nonconsecutive days to the laboratory and evaluated 2 test foods (rice and spaghetti). Their GR was measured for the subsequent 120 minutes. Mastication parameters were determined using surface electrode electromyography. The particle size distribution of individuals' masticated food was also determined. The intraindividual number of chews per mouthful did not significantly differ for rice and spaghetti (29.9 and 33, respectively), although masticated particle size distribution did (P < .001). Significant correlations between the degree of breakdown during mastication and the GR were observed for rice, but none for spaghetti. Individuals' peak GR (at 45 minutes) correlated significantly with the particles size distribution of their masticated rice (P = .002), and also with the total incremental area under the curve for the GR (r = -0.72; P = .012) and the incremental area under the curve for the first 45 (r = -0.74; P = .010) and 60 minutes (r = 0.73; P = .010) postconsumption. The results suggest that individual differences in mastication may be one of the causes for interindividual differences in the GR to rice but not spaghetti. Copyright 2010 Elsevier Inc. All rights reserved.