Health aspects of oxidized dietary fats - Oxidation in Foods and Beverages and Antioxidant Applications - page 142

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Health aspects of oxidized dietary fats
K. Eder, Institut f È r TierernÈhrung und ErnÈhrungsphysiologie
and R. Ringseis, Technical University of Munich, Germany
Abstract: This chapter addresses health-related effects associated with the
ingestion of oxidized fats. The chapter first reviews the knowledge about
nutritional quality changes and formation of lipid peroxidation products in
oxidized fats. The chapter then presents the current knowledge about effects
of oxidized fats on blood lipid profile, fatty liver development, carnitine
homeostasis, thyroid function and thyroid hormones, endogenous and
exogenous antioxidant defense mechanisms, glucose tolerance and insulin
sensitivity as well as inflammation.
Key words: oxidized fat; deep-fat frying; lipid peroxidation; PPAR.
7.1 Introduction
In recent years the contribution of oxidized fats to total energy intake has
markedly increased in industrialized countries (Guthrie et al., 2002). This is
mainly due to the rising consumption of deep-fried products, which are very
popular because of their desirable flavor, color, and crispy texture. For instance,
in a Spanish cohort from the European Prospective Investigation into Cancer and
Nutrition-Study, the percentage of energy intake from fried food was 26.4%
(men) and 22.8% (women) in the highest quintile of consumption (Guallar-
CastillÂn et al., 2007). Deep-frying is a process of immersing food in hot oil,
which acts as a heat transfer medium and contributes to the texture and flavor of
the fried food. During deep-frying several chemical reactions occur within the
oil resulting in the formation of a heterogeneous mixture of chemically distinct
substances. In addition, deep-frying causes losses of nutritive and non-nutritive