Preface

Fats and oils are a large group of chemical structures different in shape, size and physicochemical characteristics, collectively identified as lipids. Ancestrally, lipids were fundamental components in the early human diet, providing an important and valuable amount of energy (9 kcal / g 37.7 kJ / g) and other components, such as essential fatty acids, fat soluble vitamins and sterols (such as cholesterol and/or phytosterols). The different structural characteristics of lipids give them multiple biochemical, physiological and nutritional functions, being transcendental to our body and allowing, among other functions, the development and growth of highly specialized tissues, such as the brain.

Lipids have been important in the evolution of many species and especially for the human being. At present a significant number of studies have demonstrated the role of lipids in the development, prevention and / or treatment of various acute and chronic diseases. The present book, "Lipid Metabolism", discuss in its various chapters the importance of lipid metabolism in humans and other species.

The first section of the book is dedicated to the structure and general metabolism of lipids, with emphasis on the structural and metabolic differences of each lipid. Regarding lipid metabolism, the main features from their absorption and digestion are also discussed, highlighting in particular the complexity of lipoprotein metabolism.

At molecular level lipid metabolism is even more complex. Some chapters revise and discuss the close relationship between some lipids and i) the cell membrane structure ii) the regulation of intracellular signaling pathways, iii) the direct interaction with gene transcription factors iv) the regulation of gene expression, and v) the effect of lipid peroxidation in cellular metabolism. All these interactions involving lipid metabolic products show the relevance of these molecules in the maintenance of normal structural, organic and systemic cellular activity.

Currently, a central element in the study of lipid metabolism is the participation of these molecules in the development and the prevention of certain diseases, especially those of chronic non communicable nature such as, obesity, insulin resistance, diabetes mellitus, atherosclerosis, cardiovascular disease and cancer. It is well known the association of some saturated fatty acids, such as palmitic acid (C16: 0) or of

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cholesterol, with the increased risk of cardiovascular diseases, or the effect of the imbalance of omega-6 and omega-3 fatty acids in the course of inflammatory process and its posterior resolution.

An interesting aspect of lipid metabolism refers to its importance in plants where, such as in animals, lipids represent more than an energy reservoir, highlighting as regulatory elements in the metabolism and in the functional properties of many vegetables, and having a direct impact on the health and nutrition of the human and animal population.

Collectively, the book intent to be a systematic and comprehensive review of lipid structure and metabolism. Special emphasis is made to the functional characteristics of some lipids, such as membrane phospholipids. Some chapters discuss the molecular aspects of lipid metabolism, its interaction with oxidative stress, and particularly the close relationship of some lipids with health and disease.

> **Rodrigo Valenzuela Baez, Nutricionist. Msc. PhD. Assistant Professor** Fats and Oils in Food and Nutrition Research Nutrition and Dietetics School Faculty of Medicine University of Chile Santiago, Chile

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and its posterior resolution.

animal population.

cholesterol, with the increased risk of cardiovascular diseases, or the effect of the imbalance of omega-6 and omega-3 fatty acids in the course of inflammatory process

An interesting aspect of lipid metabolism refers to its importance in plants where, such as in animals, lipids represent more than an energy reservoir, highlighting as regulatory elements in the metabolism and in the functional properties of many vegetables, and having a direct impact on the health and nutrition of the human and

Collectively, the book intent to be a systematic and comprehensive review of lipid structure and metabolism. Special emphasis is made to the functional characteristics of some lipids, such as membrane phospholipids. Some chapters discuss the molecular aspects of lipid metabolism, its interaction with oxidative stress, and particularly the

**Rodrigo Valenzuela Baez, Nutricionist. Msc. PhD.** 

Fats and Oils in Food and Nutrition Research

**Assistant Professor**

Faculty of Medicine University of Chile

> Santiago, Chile

Nutrition and Dietetics School

close relationship of some lipids with health and disease.

**Section 1** 

**Introduction to Lipid Metabolism** 

**Section 1** 

**Introduction to Lipid Metabolism** 

**Chapter 1** 

© 2013 Valenzuela and Valenzuela, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is

and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

properly cited.

**Overview About Lipid Structure** 

Rodrigo Valenzuela B. and Alfonso Valenzuela B.

The term lipid is used to classify a large number of substances having very different physical - chemical characteristics, being its solubility in organic non-polar solvents the common property for their classification. Lipids are composed of carbon, hydrogen and oxygen atoms, and in some cases contain phosphorus, nitrogen, sulfur and other elements. In this context, fats and oils are the main exponents of lipids present in foods and in nutritional processes [1,2], being diverse fatty acids and cholesterol the most representative molecules due their important metabolic and nutritional functions [3,4]. The structural, metabolic and nutritional importance of lipids in the body is supported by numerous investigations in different biological models (cellular, animals and humans). Lipids have been instrumental in the evolution of species, having important role in the growth, development and maintenance of tissues [5,6]. A clear example of this importance is the elevated fatty acid concentration present in nerve tissue, especially very long-chain

Fatty acids are, among lipids, of crucial relevance in the structure and physiology of the body because: i) forms an integral part of phospholipids in cell membranes; ii) are the primary source of energy (9 kcal /g or 37.62 kjoules/g); iii) in infants, provide more than 50% of the daily energy requirements; iv) some fatty acids are of essential character and are required for the synthesis of eicosanoids and docosanoids (of 20 and 22 carbon atoms, respectively), such as leukotrienes, prostaglandins, thromboxanes, prostacyclins, protectins and resolvins), and; v) some of them may act as second messengers and regulators of gene expression [9,10]. Besides fatty acids, cholesterol is another lipid that has important functions in the body, among which are: i) together with phospholipids is important in the formation of cell membranes; ii) constitutes the skeleton for the synthesis of steroid hormones (androgens and estrogens); iii) from its structure is derived the structure of vitamin D, and; iv) participates in the synthesis of the bile salts and the composition of bile

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/52306

polyunsaturated fatty acids [7,8].

secretion [11].

**1. Introduction** 
