A Phytol-Enriched Diet Activates PPAR-α in the Liver and Brown Adipose Tissue to Ameliorate Obesity-Induced Metabolic Abnormalities.

SCOPE: Peroxisome proliferator-activated receptor alpha (PPAR-α) is a ligand-activated transcription factor that regulates lipid and carbohydrate metabolism. We investigate the effects of naturally occurring PPAR-α agonists, phytol, and its metabolite phytanic acid, on obesity-induced metabolic disorders using a mouse model. METHODS AND RESULTS: A luciferase reporter assay shows that phytanic acid potently activates PPAR-α among PPAR subtypes. In high-fat-diet-induced, severely obese mice, a phytol-enriched diet increases phytanic acid levels in the liver and adipose tissue, where PPAR-α is abundantly expressed. A phytol-enriched diet ameliorates severe obesity and the related metabolic abnormalities of white adipose tissue. Moreover, the expression of PPAR-α target genes in the liver and brown adipose tissue is enhanced by a phytol-enriched diet, suggesting that phytol and phytanic acid activate PPAR-α in these organs. We confirm that phytanic acid treatment induced PPAR-α target gene expression in both primary hepatocytes and brown adipocytes from wild-type mice, but not in these cells from PPAR-α-deficient mice. CONCLUSION: A phytol-enriched diet may increase phytanic acid levels in the liver and brown adipocytes, thereby activating PPAR-α in these organs and ameliorating obesity-induced metabolic diseases.