A Trans Fatty Acid Substitute Aggravates Nonalcoholic Steatohepatitis Induced in Mice by Feeding a Choline-Deficient, Methionine-Lowered, L-Amino Acid-Defined, High-Fat Diet

Abstract Background: Nonalcoholic steatohepatitis (NASH) is a form of liver disease characterized by steatosis, necroinflammation, and fibrosis, resulting in cirrhosis and cancer. Trans fatty acid (TFA) is hazardous for human health and a risk factor of NASH; thus, efforts have focused on reducing its intake. However, the health benefits of reducing dietary TFA are not fully elucidated. We investigated effects of TFA and its substitute on NASH induced in mice by feeding a choline-deficient, methionine-lowered, L-amino acid-defined, high-fat diet (CDAA-HF). Methods: Mice were fed CDAA-HF containing shortening with TFA (CDAA-HF-T(+)), CDAA-HF containing shortening with a TFA substitute (CDAA-HF-T(−)), or a control chow for 13/26 weeks. Results: CDAA-HF-T(+) contained TFA, whereas CDAA-HF-T(−) contained no TFA and much saturated fatty acids. CDAA-HF-T(+) and CDAA-HF-T(−) induced NASH in mice, evidenced by elevated serum transaminase activity and liver changes, including steatosis, inflammation, and fibrosis. CDAA-HF-T(−) induced more hepatocellular apoptosis and proliferative (preneoplastic and non-neoplastic) nodular lesions than CDAA-HF-T(+). Conclusions: Thus, replacement of dietary TFA with its substitute does not prevent but aggravates nutritionally induced NASH in mice, at least under the present conditions. Attention should be paid regarding future TFA substitute use in humans, and a fatty acid balance is likely more important than the particular types of fatty acids.