(P26-075-25) De Novo Aldehyde Formation, Increased Protein Carbonylation, and Altered Microbial Metabolism in the Hindgut of Pigs Fed Oxidized Soybean Oil Revealed by Metabolomics

Objectives: The consumption of thermally oxidized dietary oils has been associated with adverse health events. Previous investigations on the metabolic stress from consuming oxidized oils mainly focused on the changes in the post-absorption system, while limited research has been conducted to examine the metabolic fate of oxidized oils inside the gastrointestinal tract (GIT) as well as their influence on luminal metabolome. This study aims to characterize these events in pigs through metabolomic profiling and biochemical analysis.

Methods: Control soybean oil (CSO) was heated at 187 ℃ for 42 h with constant airflow at 30 L/min to produce oxidized soybean oil (OSO). Two groups of nursery pigs (n=30/group) were fed the diets containing 10% CSO or OSO, respectively, for 28 days ad libitum to monitor their weight and feed intake. On day 28, piglets and feed were weighed to evaluate growth performance. The liver and the digesta samples from stomach, duodenum, jejunum, ileum, cecum, and colon were collected on day 28 for metabolomics-based biochemical characterization.

Results: Heating caused dramatic elevation of oxidized triacylglycerols and aldehydes, including decadienal and 4-hydroxynonenal in OSO, leading to increased protein carbonyl (PC) in feed. OSO feeding decreased weight gain, feed intake, and gain:feed ratio, but enlarged liver, compared to the CSO feeding. Different from oils, the aldehydes in gastrointestinal digesta mainly comprised of hexanal, nonanal, and pentanal. The digesta aldehydes were more abundant in duodenum, jejunum, cecum, and colon of the OSO pigs than the CSO pigs, but comparable in ileum between two groups of pigs. This aldehyde profile along the GIT indicated de novo formation of aldehydes in the large intestine, which was consistent with the increases of PCs in cecum and colon. In addition, OSO feeding affected microbial metabolism in the large intestine, as evidenced by reduced levels of propionic acid and butyric acid.

Conclusions: The consumption of oxidized oil increased aldehydes in the large intestine through de novo formation, accompanied by increased protein oxidation and decreased volatile fatty acids. These observations warrant further investigations into their pathophysiological significance.

Funding Sources: Agricultural Experiment Station project MIN-18-125 (C. C.) from the United States Department of Agriculture (USDA).