Effects of chronic intake of starch-, glucose- and fructose-containing diets on eating behaviour in adult minipigs

- Glucose-containing diet is preferred to fructose- and starch-containing diets in naïve adult minipigs.
- Adult minipigs displayed a higher motivation to obtain glucose than fructose rewards.
- Minipigs chronically fed a fructose diet developed a strong preference for fructose.
- Minipigs fed a glucose diet did not develop a higher preference for glucose.
- Future studies should focus on the mechanisms of fructose-induced fructose preference.

IntroductionThe aim of this study was to assess whether chronic intake of isocaloric high-fat diets differing partly in the source of carbohydrates (starch, glucose or fructose) and fed at the same level of intake impacts eating behaviour in the adult Yucatan minipig.MethodsAdult minipigs were offered for 8 weeks either of three high-fat diets in which 20% of dry matter weight (36.3% of metabolizable energy) was provided as pure maize starch (SD), glucose (GD) or fructose (FD) (n = 5 per diet). Three eating behaviour tests, including a three-feed choice test, an eating microstructure test and operant conditioning with progressive ratio test were performed before and after dietary treatment in order to evaluate the impact of these carbohydrates on feed preferences and animal's motivation.ResultsAfter 8-week treatment, all groups had similar increases in body weight (from 36.2 ± 1.2 to 57.5 ± 0.1 kg, P < 0.0001). Animals showed initial preference and higher motivation for the GD over the SD, FD being intermediate. Importantly, only pigs chronically fed the FD developed a large preference for this diet: increase in FD intake (from 15 ± 3 to 35 ± 6 g/kg0.75, P < 0.05). After 8 weeks of experimental diets, intake speed of FD (19 ± 6 g/min) was higher compared to GD and SD (P = 0.001).ConclusionOur data indicate that chronic intake of diets differing in a part of the carbohydrate source induced substantial weight gain, regardless of the carbohydrate source. Pigs' initial preference and higher motivation was for the GD, compared to SD and FD. Intake of the fructose-containing diet for 8 weeks induced a stronger preference for this diet. Our data may have important implications in terms of impact of prolonged fructose consumption on eating behaviour in humans.