Olive leaf extract attenuates cardiac, hepatic, and metabolic changes in high carbohydrate-, high fat-fed rats

J Nutr. 2010 May;140(5):946-53. doi: 10.3945/jn.109.117812. Epub 2010 Mar 24.


Olive oil, an important component of the Mediterranean diet, produces cardioprotective effects, probably due to both oleic acid and the polyphenols such as oleuropein and hydroxytyrosol. Our aim in this study was to assess whether a polyphenol-enriched extract from the leaves of Olea europaea L. with oleuropein as the major component attenuated the cardiovascular, hepatic, and metabolic signs of a high-carbohydrate, high-fat (HCHF) diet (carbohydrate, 52%; fat, 24%, 25% fructose in drinking water) in rats. Male Wistar rats were fed either a cornstarch diet (CS) or a HCHF diet for a total of 16 wk. Diets of the treatment groups [CS+olive leaf extract (OLE) and HCHF+OLE] were supplemented with 3% OLE after 8 wk of being fed their respective CS or HCHF diets for a further 8 wk. After 16 wk, HCHF rats developed signs of metabolic syndrome, including elevated abdominal and hepatic fat deposition, collagen deposition in heart and liver, cardiac stiffness, and oxidative stress markers (plasma malondialdehyde and uric acid concentrations), with diminished aortic ring reactivity, abnormal plasma lipid profile, impaired glucose tolerance, and hypertension. Compared with HCHF rats, those in the HCHF+OLE group had improved or normalized cardiovascular, hepatic, and metabolic signs with the exception of elevated blood pressure. These results strongly suggest that an OLE containing polyphenols such as oleuropein and hydroxytyrosol reverses the chronic inflammation and oxidative stress that induces the cardiovascular, hepatic, and metabolic symptoms in this rat model of diet-induced obesity and diabetes without changing blood pressure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antioxidants / pharmacology
  • Antioxidants / therapeutic use*
  • Biomarkers / metabolism
  • Diabetes Mellitus, Experimental / complications
  • Diabetes Mellitus, Experimental / drug therapy*
  • Diabetes Mellitus, Experimental / metabolism
  • Dietary Carbohydrates / administration & dosage
  • Dietary Fats / administration & dosage
  • Dietary Fats / metabolism
  • Disease Models, Animal
  • Flavonoids / pharmacology
  • Flavonoids / therapeutic use*
  • Glucose Intolerance / drug therapy
  • Glucose Intolerance / metabolism
  • Heart / drug effects
  • Hypertension / drug therapy
  • Inflammation / drug therapy
  • Liver / metabolism
  • Male
  • Metabolic Syndrome / complications
  • Metabolic Syndrome / drug therapy*
  • Metabolic Syndrome / metabolism
  • Myocardium / metabolism
  • Obesity / complications
  • Obesity / drug therapy*
  • Obesity / metabolism
  • Olea / chemistry*
  • Oxidative Stress / drug effects
  • Phenols / pharmacology
  • Phenols / therapeutic use*
  • Phenylethyl Alcohol / analogs & derivatives
  • Phenylethyl Alcohol / pharmacology
  • Phenylethyl Alcohol / therapeutic use
  • Phytotherapy
  • Plant Extracts / pharmacology
  • Plant Extracts / therapeutic use*
  • Plant Leaves
  • Polyphenols
  • Rats
  • Rats, Wistar


  • Antioxidants
  • Biomarkers
  • Dietary Carbohydrates
  • Dietary Fats
  • Flavonoids
  • Phenols
  • Plant Extracts
  • Polyphenols
  • 3,4-dihydroxyphenylethanol
  • Phenylethyl Alcohol