Involvement of Inflammation and Adverse Vascular Remodelling in the Blood Pressure Raising Effect of Repeatedly Heated Palm Oil in Rats

Chun-Yi Ng,Hj Mohd Saad Qodriyah,Kamsiah Jaarin,Yusof Kamisah,Zakiah Jubri,Othman Faizah

doi:10.1155/2012/404025

Chun-Yi Ng, Hj Mohd Saad Qodriyah + Show 4 more

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https://doi.org/10.1155/2012/404025

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Abstract

Oil thermoxidation during deep frying generates harmful oxidative free radicals that induce inflammation and increase the risk of hypertension. This study aimed to investigate the effect of repeatedly heated palm oil on blood pressure, aortic morphometry, and vascular cell adhesion molecule-1 (VCAM-1) expression in rats. Male Sprague-Dawley rats were divided into five groups: control, fresh palm oil (FPO), one-time-heated palm oil (1HPO), five-time-heated palm oil (5HPO), or ten-time-heated palm oil (10HPO). Feeding duration was six months. Blood pressure was measured at baseline and monthly using tail-cuff method. After six months, the rats were sacrificed and the aortic arches were dissected for morphometric and immunohistochemical analyses. FPO group showed significantly lower blood pressure than all other groups. Blood pressure was increased significantly in 5HPO and 10HPO groups. The aortae of 5HPO and 10HPO groups showed significantly increased thickness and area of intima-media, circumferential wall tension, and VCAM-1 than other groups. Elastic lamellae were disorganised and fragmented in 5HPO- and 10HPO-treated rats. VCAM-1 expression showed a significant positive correlation with blood pressure. In conclusion, prolonged consumption of repeatedly heated palm oil causes blood pressure elevation, adverse remodelling, and increased VCAM-1, which suggests a possible involvement of inflammation.

Highlights

The practice of reusing vegetable oils several times for deep frying before disposing them is quite common among Malaysians
This oxidative deterioration affects the chemical compositions of the vegetable oils by saturating its fatty acids and generating reactive oxygen species (ROS) which are potential in causing deleterious effects on the normal function of endothelial cells [2] and increasing risk of hypertension [3, 4]
The rats were divided into five groups comprising six animals each and given the following course of diet: (i) basal diet without any addition of oil or basal diet fortified with 15% weight/weight (w/w), (ii) fresh palm oil (FPO) as described earlier by Owu et al [21], (iii) onetime-heated palm oil (1HPO), (iv) five-time-heated palm oil (5HPO), or (v) ten-time-heated palm oil (10HPO) for six months

Summary

Introduction

Heating the vegetable oils to a high level of temperature, that is, approximately 160–180◦C, exposes them to the air and moisture at the same time, in which the oils will undergo a complex series of physical and chemical deterioration known as oil thermoxidation. This oxidative deterioration affects the chemical compositions of the vegetable oils by saturating its fatty acids and generating reactive oxygen species (ROS) which are potential in causing deleterious effects on the normal function of endothelial cells [2] and increasing risk of hypertension [3, 4]

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