Abbreviations ......................................................................................................... 166 Introduction to Fatty Acids .................................................................................... 166

Denitions ......................................................................................................... 167 Nomenclature of Unsaturated Fatty Acids ........................................................ 167

Essential Fatty Acids .............................................................................................. 168 Sources of EFA ................................................................................................. 169

Dietary Sources of LA .................................................................................. 169 Dietary Sources of ALA ............................................................................... 169 Sources of Arachidonic Acid ........................................................................ 170 Dietary Sources of EPA and DHA ............................................................... 170 Biosynthesis of EPA and DHA in Humans .................................................. 171

EFA Deciency ................................................................................................. 174 LA Deciency Symptoms ............................................................................ 175 EFA Deciency Diagnosis ........................................................................... 175 ALA Deciency Symptoms ......................................................................... 176

Functions of Omega-3 Fatty Acids .................................................................... 177 Physiological Effects of ALA ....................................................................... 178 EPA-Specic Functions ................................................................................ 179 Prostanoids and Leukotrienes ....................................................................... 181 Lipoxins ........................................................................................................ 182 DHA-Specic Functions .............................................................................. 183 Cell Membrane Phospholipids ..................................................................... 183 Brain Phospholipids ..................................................................................... 184

Evolution of the Human Brain ............................................................................... 186 Dietary Imbalance of EFAs .................................................................................... 188 Recommended Daily Intakes ................................................................................. 189 Modern Nutraceuticals ........................................................................................... 191 Concluding Remarks .............................................................................................. 193 Acknowledgment ................................................................................................... 193 References .............................................................................................................. 193

AA arachidonic acid (20:5n-6) ALA alpha-linolenic acid or linolenic acid (18:3n-3) C carbon atom COX cyclooxygenase D5D delta-5 desaturase D6D delta-6 desaturase DHA docosahexaenoic acid (22:6n-3) DPA docosapentaenoic acid (22:5n-3) EFA essential fatty acid EPA eicosapentaenoic acid (20:5n-3) EPO evening primrose oil FA fatty acids LA linoleic acid (18:2n-6) LC longer chain (≥20 carbon atoms) LOX lipoxygenase LT leukotriene LX lipoxin n-3 omega-3 n-6 omega-6 PD protectin PG prostaglandin PL phospholipids PUFA polyunsaturated fatty acid Rv resolvin TX thromboxane

The word “fat” can be traced back to the Sanskrit word payate meaning “swells, grows, fattens.” In Latin it was pinguis, in Greek pakus, and an old Anglo-Saxon word faet, meant “to fatten.” Its rst formal appearance in the English language was in 1539, when it was dened as the “oily concrete substance of which the fat parts of animal bodies are chiey composed” [1].