Essential Fatty Acids

Essential fatty acids, or EFAs, are <a href="http://en.wikipedia.org/wiki/Fatty_acid" title="Fatty acid" >fatty acids</a> that humans and other animals must ingest because the body requires them for good health but cannot <a href="http://en.wikipedia.org/wiki/Biosynthesis" title="Biosynthesis" >synthesize</a> them.<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-0" >[1]</a>

The term "essential fatty acid" refers to fatty acids required for biological processes, and not those that only act as fuel.

Only two EFAs are known for humans: <a href="http://en.wikipedia.org/wiki/Alpha-linolenic_acid" title="Alpha-linolenic acid" class="mw-redirect" >alpha-linolenic acid</a> (an <a href="http://en.wikipedia.org/wiki/Omega-3_fatty_acid" title="Omega-3 fatty acid" >omega-3 fatty acid</a>) and

<a href="http://en.wikipedia.org/wiki/Linoleic_acid" title="Linoleic acid" >linoleic acid</a> (an <a href="http://en.wikipedia.org/wiki/Omega-6_fatty_acid" title="Omega-6 fatty acid" >omega-6 fatty acid</a>).<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-1" >[2]</a><a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-2" >[3]</a><a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-3" >[4]</a>

In the body, essential fatty acids serve multiple functions. In each of these, the balance between dietary ω-3 and ω-6 strongly affects function.

<ul >

<li >They are modified to make

<ul >

<li >the classic <a href="http://en.wikipedia.org/wiki/Eicosanoid" title="Eicosanoid" >eicosanoids</a> (affecting <a href="http://en.wikipedia.org/wiki/Inflammation" title="Inflammation" >inflammation</a> and many other cellular functions)</li>

<li >the <a href="http://en.wikipedia.org/wiki/Cannabinoid#Endocannabinoids" title="Cannabinoid" >endocannabinoids</a> (affecting mood, behavior and inflammation)</li>

<li >the <a href="http://en.wikipedia.org/wiki/Lipoxin" title="Lipoxin" >lipoxins</a> from ω-6 EFAs and <a href="http://en.wikipedia.org/wiki/Resolvins" title="Resolvins" class="mw-redirect" >resolvins</a> from ω-3 (in the presence of aspirin, downregulating inflammation.)</li>

<li >the <a href="http://en.wikipedia.org/wiki/Isofuran" title="Isofuran" >isofurans</a>, <a href="http://en.wikipedia.org/wiki/Neurofuran" title="Neurofuran" >neurofurans</a>, <a href="http://en.wikipedia.org/wiki/Isoprostane" title="Isoprostane" >isoprostanes</a>, <a href="http://en.wikipedia.org/wiki/Hepoxilin" title="Hepoxilin" >hepoxilins</a>, <a href="http://en.wikipedia.org/wiki/Epoxyeicosatrienoic_acid" title="Epoxyeicosatrienoic acid" >epoxyeicosatrienoic acids</a> (EETs) and <a href="http://en.wikipedia.org/wiki/Neuroprotectin" title="Neuroprotectin" >Neuroprotectin D</a></li>

</ul>

</li>

<li >They form <a href="http://en.wikipedia.org/wiki/Lipid_raft" title="Lipid raft" >lipid rafts</a> (affecting cellular signaling)<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-WStillwell-6" >[7]</a></li>

<li >They act on DNA (activating or inhibiting transcription factors such as <a href="http://en.wikipedia.org/wiki/NF-%CE%BAB" title="NF-κB" >NF-κB</a>, which is linked to pro-inflammatory<a href="http://en.wikipedia.org/wiki/Cytokine" title="Cytokine" >cytokine</a> production)<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-PCalder-7" >[8]</a></li>

</ul>

Essential fatty acids play an important role in the life and death of cardiac cells.<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-13" >[14]</a><a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-14" >[15]</a><a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-15" >[16]</a><a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-16" >[17]</a>

Research suggests that high intakes of fish and omega-3 fatty acids are linked to decreased rates of major depression. Omega-3 fatty acids, such as <a href="http://en.wikipedia.org/wiki/Docosahexaenoic_acid" title="Docosahexaenoic acid" >docosahexaenoic acid</a> (DHA) and <a href="http://en.wikipedia.org/wiki/Eicosapentaenoic_acid" title="Eicosapentaenoic acid" >eicosapentaenoic acid</a> (EPA) are important for enzymatic pathways required to metabolize <a href="http://en.wikipedia.org/w/index.php?title=Long-chain_polyunsaturated_fatty_acids&action=edit&redlink=1" class="new" title="Long-chain polyunsaturated fatty acids (page does not exist)" >long-chain polyunsaturated fatty acids</a> (PUFAs). Low plasma concentrations of DHA predict low concentrations of cerebrospinal fluid <a href="http://en.wikipedia.org/wiki/5-hydroxyindoleacetic_acid" title="5-hydroxyindoleacetic acid" class="mw-redirect" >5-hydroxyindoleacetic acid</a> (5-HIAA). It is found that low concentrations of 5-HIAA in the brain is associated with depression and suicide.<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-pmid15777365-18" >[19]</a>

Other fatty acids that are only "conditionally essential" include <a href="http://en.wikipedia.org/wiki/Gamma-linolenic_acid" title="Gamma-linolenic acid" class="mw-redirect" >gamma-linolenic acid</a> (an omega-6 fatty acid), <a href="http://en.wikipedia.org/wiki/Lauric_acid" title="Lauric acid" >lauric acid</a> (a saturated fatty acid), and <a href="http://en.wikipedia.org/wiki/Palmitoleic_acid" title="Palmitoleic acid" >palmitoleic acid</a> (a monounsaturated fatty acid).<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-4" >[5]</a>

When the two EFAs were first discovered in 1923, they were designated Vitamin F.

In 1930, work by Burr, Burr and Miller on rats showed that the two EFAs are better classified with the <a href="http://en.wikipedia.org/wiki/Fat" title="Fat" >fats</a> than with the <a href="http://en.wikipedia.org/wiki/Vitamin" title="Vitamin" >vitamins</a>.<a href="http://en.wikipedia.org/wiki/Essential_fatty_acid#cite_note-Burr-5" >[6]</a>