When frying oil is heated at high temperatures, hydroperoxides
and aldehydes are formed. These toxic products are absorbed by the
food, and eventually into the gastrointestinal tract and thereafter enter
the systemic circulation after ingestion [2]. We recently reported
that intake of repeatedly heated palm and soybean oils significantly
increased the blood pressure in experimental animals [3,4]. In
addition, Soriguer et al. [5] reported that consumption of repeatedly
heated frying oils is associated with increased risk of hypertension.
The practice of reusing frying oil leads to detrimental health risks such
as histological abnormalities [6-9] and alterations in genetic material
[10-12]. Free radicals generated during the frying process could
damage membrane lipids through lipid peroxidation, subsequently
leading to oxidative stress. This review examines the current
literature on the harmful effects of repeatedly heated vegetable oils
on antioxidant activity, lipid peroxidation and endothelial function