The effect of a three week high fat diet on the mouth to caecum transit time of a high fat meal in humans

Abstract

Adaptation to a high fat diet is an important early stage in the pathogenesis of obesity [I]. It has been suggested previously [2,3] that subjects provided with artificial diets of varying fat content have shorter mouth to caecum transit times (MCTT) with increased dietary fat.The aim of this study was to examine whether there are changes in MCTT of a high fat meal during a period of consuming a diet containing an increased amount of fat. To reduce variability within the study, habitual food intake was manipulated to produce a high fat diet rather than the normal procedure of providing comparison between two artificial diets.With the approval of the local ethics committee (South Sheffield Ethics Committee, Royal Hallamshire Hospital, Sheffield), six healthy males volunteered for this study. Their physical characteristics (median (range)) were: age 27 (21-34), height 179 cm (170-189) and weight 69 kg (58.5-78.9) at the start of the test period. Subjects were chosen who were in general good health with no known history of gastro-intestinal pathology and who were not on any medication. Subjects were excluded if their Body Mass Index did not lie within a range of 19-25 kg/m'. Subjects were excluded if they consumed more than 35% of their total energy as fat above which subjects would be pre-adapted to a high fat diet as defined by Committee on Medical Aspects of Food Policy, 1994.Subjects recorded all food and drink consumed over a seven day period before MCTT of a high fat test meal (2840 kJ, 85 % fat by energy) was recorded. The test meal contained sufficient fibre (12 g) to allow for recording of MCTT by breath hydrogen analysis [4]. End expiratory breath samples were before and at 10 minute intervals after ingestion of the test meal. MCTT of the head of the test meal was taken as the time after ingestion at which there was a rise of 3 ppm above basal values which was maintained or increased over the next three consecutive 10 minute readings [5].For the subsequent three weeks, volunteers repeated the food diary. They also consumed high fat food sources to increase the content of fat in the diet. Subjects were provided with 125 ml of double cream and 50 g of roasted peanuts each day which increased the mean daily energy intake of 11 125 kJ (sem 457) (30 % fat (sem 1.4)) to a mean of 14960 kJ (46 % fat). The refined diet led to a mean increase of 1.1 kg (sem 0.1) in subjects' weights (p = 0.0085).During this period, MCTI' of the same test meal was measured at seven, fourteen and twenty-one days after the start of their high fat diet. Transit times measured at these weekly intervals and before the new diet were compared using repeated measures ANOVA. Significance was taken at 5%.There were significant differences between MCTT at the different stages of early adaptation to a high fat diet (p = 0.006) with MCTT significantly longer after three weeks of the new diet when compared with both before the start of the new diet (p = 0.027) and after just one week of the new regimen (p = 0.045) as shown in figure 1. There was ...