The objective of the present explorative study was to determine the absorption dynamics when feeding diets varying in types and levels of dietary fibre in a catheterised animal model. A total of six sows were fed a diet low in fibre (LF), a diet high in soluble fibre and a diet high in insoluble fibre in a repeated 3 × 3 cross-over design. Plasma samples were collected from the mesenteric artery and the portal vein to determine different absorption phases by 1H NMR spectroscopy-based metabonomics. Time profiles were determined for plasma levels of specific metabolites and for the absorption of these metabolites from the small intestine. The LF diet resulted in a higher betaine concentration in the blood than the two high-fibre diets (P = 0·008). This leads to higher plasma concentrations of methionine (P = 0·0028) and creatine (P = 0·020) of endogenous origin. In conclusion, the use of NMR spectroscopy for measuring nutrient uptake in the present study elucidated the relationship between betaine uptake and elevated creatine plasma concentrations.