High-fat diet from perilla oil induces insulin resistance despite lower serum lipids and increases hepatic fatty acid oxidation in rats.
Level 5 - mechanism / opinion, no new human data
Animal research (rodent study)
PubMed 24422660 · doi:10.1186/1476-511X-13-15
What was done
Male Sprague-Dawley rats were fed either a control diet or a high-fat diet rich in perilla oil for 16 weeks. Researchers measured serum lipids (triglycerides, total cholesterol, HDL-c, LDL-c, free fatty acids), body weight, and intrahepatic lipid deposition. They quantified hepatic mRNA and protein expression of fatty acid oxidation markers (PPAR-alpha, CPT1A) and synthesis markers (SREBP-1, FASN, ACC), and evaluated insulin sensitivity using a euglycemic-hyperinsulinemic clamp.
What was found
Compared with the control group, rats on the high perilla oil diet had significantly decreased serum triglyceride, total cholesterol, and HDL-cholesterol levels. LDL-cholesterol, free fatty acids, intrahepatic lipids, and body weight did not change. In the liver, mRNA expression of PPAR-alpha, CPT1A, SREBP-1, FASN, and ACC increased; CPT1A protein levels increased, whereas FASN and ACC protein levels decreased. The glucose infusion rate during clamp was reported as significantly increased in the perilla oil group compared to controls. No absolute numerical values were reported in the abstract.
Why it matters
This study shows that excessive perilla oil intake in rodents promotes hepatic fatty acid oxidation pathways and lowers circulating lipids, but alters systemic glucose metabolism.
Limits
Findings are restricted to male rats and cannot establish effects in humans. The abstract omits sample sizes (n), specific dietary fat compositions, and all exact numerical values and effect sizes for the measured endpoints.
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