Mechanisms of food reduction, transport and deglutition: How the texture of food affects feeding behavior

This review reports on the results of videofluorographic (VFG) studies focused on establishing the characteristics of the feeding sequence and the effect of food type on that behavior in normal human subjects. Lateral projection VFG records vertical and antero-postetior movement. The Postero-Anterior projection records vertical and medio-lateral movement. Both were used. Normal young adults of both sexes were fully consenting participants in these studies. They were fed 6 g of banana, chicken spread, cookie and peanuts. A second study used 1 g carrot instead of the peanuts. In a third, 6 g of meat with different textures was supplied. The methods are fully detailed in Palmer et al. (1992, 1997). Analysis of feeding sequences using the stop-frame, slow motion and variable speed controls on the VCR gave data on the timing and so duration of 'in sequence stages': i.e., start Stage I transport; start processing; start Stage II transport (i.e., start OPAT) and also the swallow and its duration. Parts of the feeding sequence show a very significant difference (P < 0.0001) between soft (banana and chicken spread) and harder foods (meat, cookie and carrot) in (1) the duration of processing and (2) OroPharyngeal Accumulation Time (OPAT). There were no such differences for Stage I transport or the actual swallow. These results show that the texture dependent parts of the feeding sequence are those associated with food breakdown (processing/chewing) and with OPAT. The results also show that there is a general pattern of response to foods of different initial consistency/texture. However, individual subjects have their own behaviors in managing these foods to terminal swallow.