Similar metabolic responses in pigs and humans to breads with different contents and compositions of dietary fibers: a metabolomics study1-3

Background: In nutritional studies, pigs are often used as models for humans because of nutritional and physiologic similarities. However, evidence supporting similar metabolic responses to nutritional interventions is lacking. Objective: The objective was to establish whether pigs and humans respond similarly to a nutritional intervention. Using metabolomics, we compared the acute metabolic response to 4 test breads between conventional pigs (growing) and adult human subjects (with the metabolic syndrome). Design: Six catheterized pigs and 15 human subjects were tested in a randomized crossover design with 4 breads: white-wheat bread low in dietary fiber, rye bread with whole-rye kernels, and 2 white-wheat breads supplemented with either wheat arabinoxylan or oat beta-glucan. Blood samples drawn -15, 30, and 120 min postprandially were analyzed by untargeted liquid chromatography-mass spectrometry metabolomics. Results: We found that the postprandial responses, as reflected in blood metabolomes, are similar in pigs and humans. Twenty-one of 26 identified metabolites that were found to be different between the species were qualitatively similar in response to the test breads, despite different basal metabolome concentrations in the plasma of pigs and humans. Humans had higher contents of phosphatidylcholines, oleic acid, and carnitine in plasma, possibly reflecting a higher intake of meats and fats. In pigs, betaine, choline, creatinine, tryptophan, and phenylalanine were higher, probably because of the higher doses of bread provided to the pigs (per kg body weight) and/ or because of their growing status. Acute metabolic differences in these metabolites induced by the breads were, however, comparable between the 2 species. Conclusion: Our results indicate that pigs are a suitable model for human metabolic studies in food research. The human trial was registered at clinicaltrials. gov as NCT01316354. The animal experiment was conducted according to a license obtained by the Danish Animal Experiments Inspectorate, Ministry of Food, Agriculture and Fisheries, Danish Veterinary and Food Administration.