Effects of polar compounds in fried palm oil on liver lipid metabolism in C57 mice.

Polar components (PCs) are produced during the frying of oil, affecting the quality of edible oil and posing a hazard to human health. In this study, C57 mice were fed a high-fat (HF) diet containing purified PCs for nine weeks. Their effects on lipid metabolism and liver function in animals were analyzed. Our results indicated that the contents of total PCs and saturated fatty acid increased from 6.07 ± 0.6% and 58.27 ± 0.35% to 19.17 ± 1.8% and 69.91 ± 0.51%, respectively (P < 0.01). PC intake resulted an 18.56% higher liver index in mice than that in the HF group. The PC group had the highest malondialdehyde (MDA) content (1.94 ± 0.11 nmol/mg protein) and the liver nonalcoholic fatty liver disease (NAFLD) activity score (NAS) was 4, which already showed NAFLD characteristics. In addition, the expression levels of lipid metabolism-related genes, including sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthetase (FAS), peroxisome proliferator-activated receptor-alpha, and peroxisome acyl-CoA oxidase 1, indicated that PC increased hepatic lipid accumulation by upregulating the transcriptional level of fat synthesis genes and further leads to liver damage by affecting mitochondrial function. Our results provided important information about the effects of PCs produced in the frying process of PO on animal health, which is critical for assessing the biosafety of fried products. PRACTICAL APPLICATION: The research will help promote the industrial upgrading of fried foods and help consumers build healthy lifestyles.