Effects of Repeated Heating of Cooking Oils on Antioxidant Content and Endothelial Function

Review Article

Austin J Pharmacol Ther. 2015; 3(2).1068.

Effects of Repeated Heating of Cooking Oils on Antioxidant Content and Endothelial Function

Leong XF1,2, Ng CY¹, Jaarin K¹ and Mustafa MR³*

¹Department of Pharmacology, Universiti Kebangsaan Malaysia, Malaysia

²Department of Clinical Oral Biology, Universiti Kebangsaan Malaysia, Malaysia

³Department of Pharmacology, University of Malaya, Malaysia

*Corresponding author: : Mustafa MR, Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia

Received: October 07, 2014; Accepted: April 03, 2015; Published: April 07, 2015


Reusing cooking oil in food preparation, especially during deep-frying, is a common practice to save costs. Repeated heating of the oil accelerates oxidative degradation of lipids, forming hazardous reactive oxygen species and depleting the natural antioxidant contents of the cooking oil. Long-term ingestion of foods prepared using reheated oil could severely compromise one’s antioxidant defense network, leading to pathologies such as hypertension, diabetes and vascular inflammation. The detrimental effects of reheated oil consumption extend beyond mere oxidative assault to cellular antioxidant shield. In this review, we have examined the experimental and clinical effects related to the intake of reheated oil on antioxidant contents, membrane lipid peroxidation and endothelial function. Understanding the mechanisms underlying the pathology associated with intake of repeatedly heated oil will help to set a reference for assessing the safety of cooking oil. Finally, considering the potential hazard of repeatedly heating oil, this article aims to further increase awareness of the general public regarding the health risks associated with these oils.

Keywords: Antioxidant; Endothelial dysfunction; Heating; Lipid peroxidation; Oxidative stress; Vegetable oils


According to the United States Department of Agriculture, 168.85 million metric tons of vegetable oils are estimated to be produced globally at the end of 2013-2014 season [1]. World vegetable oil production has increased over the past decades, especially production of palm oil, soybean oil, rapeseed oil (canola) and sunflower oil (Table 1). Vegetable oils are regarded as the healthier choice relative to animal fats in view of their unsaturated fatty acid and cholesterolfree contents. In this fast-paced society, frying remains as one of the popular methods in food preparation. Consumption of ready-made deep-fried food is high, especially in developing countries. Highly oxidized fatty acids are consumed through intake of these fried foods. Edible vegetable oil is the major ingredient in these fried food products. Therefore, the cost of the oil becomes the most important factor to be considered in terms of economy. As a result, vegetable oil is often to be repeatedly heated to ensure cost effectiveness. The oil is thus reused until it is discarded and replaced with fresh oil.