ABSTRACT
I. INTRODUCTION Fatty acids serve a wide variety of metabolic functions critical to all forms of life. They are a rich source of energy and carbon and well designed as a convenient unit for energy storage. However, the importance of fatty acids in human nutrition and physiology goes well beyond their role as a source of calories. Fatty acids provide the structure and hydrophobicity crucial to the maintenance of a semipermeable membrane barrier. Their structures can be modified by desaturation and elongation to produce a substantial variety of species with individual chemical and physical properties. Ester linkages to glycerides allow fatty acids to be easily exchanged for one another and allow cells to manipulate the physical properties of their membranes. Fatty acids also serve as precursors to active signal molecules such as eicosanoids, which are capable of producing potent biological effects. Evolution has produced a distinction between plants and animals in their capabilities for the metabolism of fatty acids. Higher animals are unable to synthesize all of the fatty acids required for certain tissue functions and are obligated to ingest fatty acids that are synthesized by plants. Animals have evolved a separate and distinct series of metabolic modifications of fatty acids, but are still unable to alter the original modifications inserted by plants. As a result, the membrane, signal, and storage lipids of animals vary widely according to their dietary intakes. In addition, the ability of an animal to produce a specific fatty acid relies either on an inherent mechanism for desaturation of saturated fatty acids or on the ingestion of a convertible precursor. The ingestion for a variety
of physiological and cellular functions. Inadequate intake or defective metabolism leads to various dysfunctions due to deficiencies of these fatty acids in particular cellular locations. In addition, dietary fatty acids have been well correlated with metabolic and physiological alterations associated with heart disease and cancer [13]. Unsaturated fatty acids in particular play an important role in these non-energyproducing metabolic functions.
