Bioactive lipids in metabolic syndrome.

The metabolic syndrome is a cluster of metabolic disorders, such as abdominal obesity, dyslipidemia, hypertension and impaired fasting glucose that contribute to increased cardiovascular morbidity and mortality. Although the pathogenesis of metabolic syndrome is complicated and the precise mechanisms have not been elucidated, dietary lipids have been recognized as contributory factors in the development and the prevention of cardiovascular risk clustering. This review explores the physiological functions and molecular actions of bioactive lipids, such as n-3 polyunsaturated fatty acids, conjugated fatty acids, sterols, medium-chain fatty acids, diacylglycerols and phospholipids, in the development of metabolic syndrome. Dietary bioactive lipids suppress the accumulation of abdominal adipose tissue and lipids in the liver and serum, and alleviate hypertension and type 2 diabetes through the transcriptional regulation of lipid and glucose metabolism. Peroxisome proliferator-activated receptors (PPARs), sterol regulatory element binding proteins, liver X receptor alpha, retinoid X receptor alpha, farnesoid X receptor alpha, hepatic nuclear factor 4alpha and nuclear factor kappaB contribute to these nuclear actions of bioactive lipids with complex interactions. Recent studies have demonstrated the striking ability of bioactive lipids to regulate the production of physiologically active adipocytokines through PPARgamma activation. In particular, the function of bioactive lipids as dietary adiponectin inducers (dietary insulin sensitizers) deserves attention with respect to alleviation of metabolic syndrome by dietary manipulation.