Editing Fatty acid (section)

===Metabolism===
{{Main|Fatty acid metabolism}}
Fatty acids are broken down to CO{{sub|2}} and water by the intra-cellular [[mitochondria]] through [[beta oxidation]] and the [[citric acid cycle]]. In the final step ([[oxidative phosphorylation]]), reactions with oxygen release a lot of energy, captured in the form of large quantities of [[Adenosine triphosphate|ATP]]. Many cell types can use either [[glucose]] or fatty acids for this purpose, but fatty acids release more energy per gram. Fatty acids (provided either by ingestion or by drawing on triglycerides stored in fatty tissues) are distributed to cells to serve as a fuel for muscular contraction and general metabolism.

====Essential fatty acids====
{{Main|Essential fatty acid}}
Fatty acids that are required for good health but cannot be made in sufficient quantity from other substrates, and therefore must be obtained from food, are called essential fatty acids. There are two series of essential fatty acids: one has a double bond [[Omega-3 fatty acid|three carbon atoms]] away from the methyl end; the other has a double bond [[Omega-6 fatty acid|six carbon atoms]] away from the methyl end. Humans lack the ability to introduce double bonds in fatty acids beyond carbons 9 and 10, as counted from the carboxylic acid side.<ref>{{cite book|last=Bolsover|first=Stephen R.|title=Cell Biology: A Short Course|url=https://books.google.com/books?id=3a6p9pA5gZ8C&pg=PA42+|date=15 February 2004|publisher=John Wiley & Sons|isbn=978-0-471-46159-3|pages=42ff|display-authors=etal}}</ref> Two essential fatty acids are [[linoleic acid]] (LA) and [[α-Linolenic acid|alpha-linolenic acid]] (ALA). These fatty acids are widely distributed in plant oils. The human body has a limited ability to convert ALA into the longer-chain [[omega-3 fatty acid]]s — [[eicosapentaenoic acid]] (EPA) and [[docosahexaenoic acid]] (DHA), which can also be obtained from fish. Omega−3 and [[Omega-6 fatty acid|omega−6]] fatty acids are [[Biosynthesis|biosynthetic]] precursors to [[Cannabinoid#Endocannabinoids|endocannabinoids]] with [[Nociception|antinociceptive]], [[anxiolytic]], and [[Nervous system|neurogenic]] properties.<ref>{{Cite journal|last1=Ramsden|first1=Christopher E.|last2=Zamora|first2=Daisy|author-link3=Alexandros Makriyannis|last3=Makriyannis|first3=Alexandros|last4=Wood|first4=JodiAnne T.|last5=Mann|first5=J. Douglas|last6=Faurot|first6=Keturah R.|last7=MacIntosh|first7=Beth A.|last8=Majchrzak-Hong|first8=Sharon F.|last9=Gross|first9=Jacklyn R.|date=August 2015|title=Diet-induced changes in n-3 and n-6 derived endocannabinoids and reductions in headache pain and psychological distress|journal=The Journal of Pain|volume=16|issue=8|pages=707–716|doi=10.1016/j.jpain.2015.04.007|issn=1526-5900|pmc=4522350|pmid=25958314}}</ref>