Citrus flavonoids and lipid metabolism.

Citrus flavonoids are polyphenolic compounds with powerful biological properties. This review aims to summarize recent advances towards understanding the ability of citrus flavonoids to regulate lipid metabolism and other metabolic parameters relevant to the metabolic syndrome, type 2 diabetes and cardiovascular disease. Citrus flavonoids, including naringenin, hesperidin, nobiletin and tangeretin, have emerged as promising therapeutic agents for the treatment of metabolic dysregulation. Epidemiological studies report that intake of citrus flavonoid-containing foods attenuates cardiovascular diseases. Experimental and a limited number of clinical studies reveal lipid-lowering, insulin-sensitizing, antihypertensive and anti-inflammatory properties. In animal models, citrus flavonoid supplements prevent hepatic steatosis, dyslipidemia and insulin sensitivity primarily through inhibition of hepatic fatty acid synthesis and increased fatty acid oxidation. Citrus flavonoids blunt the inflammatory response in metabolically important tissues including liver, adipose tissue, kidney and the aorta. The mechanisms underlying flavonoid-induced metabolic regulation have not been completely established. In mouse models, citrus flavonoids show marked suppression of atherogenesis through improved metabolic parameters and also through direct impact on the vessel wall. These recent studies suggest an important role of citrus flavonoids in the treatment of dyslipidemia, insulin resistance, hepatic steatosis, obesity and atherosclerosis. The favorable outcomes are achieved through multiple mechanisms. Human studies focussed on dose, bioavailability, efficacy and safety are required to propel the use of these promising therapeutic agents into the clinical arena.