title: Effect of repeatedly heated palm olein on blood pressure-regulating enzymes activity and lipid peroxidation in rats.
abstract: BACKGROUND
  Oxidative stress is associated with the pathogenesis of cardiovascular diseases. The process of deep-fat frying in dietary cooking oil plays a role in the generation of free radicals. In this study, palm olein heated to 180 °C was tested for its effect on the activity of blood pressure-regulating enzymes and lipid peroxidation.
  
  
  METHODS
  Forty-two adult male Sprague-Dawley rats were equally assigned into 6 groups.The first group was fed with normal rat chow as the control group, and the subsequent groups were fed with rat chow fortified with 15% weight/weight of the following: fresh palm olein, palm olein heated once, palm olein heated twice, palm olein heated 5 times, or palm olein heated 10 times. The duration of feeding was 6 months. Fatty acid analyses of oil were performed using gas chromatography. Peroxide values were determined using standard titration. Plasma was collected for biochemical analyses.
  
  
  RESULTS
  Repeatedly heated palm olein increased the levels of peroxide, angiotensin-converting enzyme, and lipid peroxidation as well as reduced the level of heme oxygenase. Fresh palm olein and palm olein heated once had lesser effects on lipid peroxidation and a better effect on the activity of blood pressure-regulating enzymes than repeatedly heated palm olein.
  
  
  CONCLUSIONS
  Repeatedly heated palm olein may negatively affect the activity of blood pressure-regulating enzymes and increase lipid peroxidation.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, 50300 Kuala Lumpur, Malaysia.
authors.forename: Xin-Fang
authors.initials: XF
authors.lastname: Leong
authors.forename: Jumat
authors.initials: J
authors.lastname: Salimon
authors.forename: Mohd Rais
authors.initials: MR
authors.lastname: Mustafa
authors.forename: Kamsiah
authors.initials: K
authors.lastname: Jaarin