Polyunsaturated fat 1610513 223699430 2008-07-05T09:36:53Z DOI bot 6652755 Citation maintenance. Formatted: title. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Fats}} In nutrition, '''polyunsaturated fat''' is an abbreviation of polyunsaturated [[fatty acid]]. That is a fatty acid in which more than one [[double bond]] exists within the representative [[molecule]]. That is, the molecule has two or more points on its structure capable of supporting [[hydrogen]] [[atoms]] not currently part of the structure. Polyunsaturated [[fatty acids]] can assume a ''[[cis]]'' or ''[[trans]]'' [[Conformational isomerism|conformation]] depending on the geometry of the double bond. The lack of the extra hydrogen atoms on the molecule's surface typically reduces the strength of the compound's [[intermolecular force]]s, thus causing the [[melting point]] of the compound to be significantly lower. This property can be observed by comparing predominately [[unsaturated]] [[vegetable]] [[oil]]s, which remain [[liquid]] even at relatively low temperatures, to much more [[saturated fat|saturated]] fats such as [[butter]] or [[lard]] which are mainly [[solid]] at [[room temperature]]. [[Trans fats]] are more similar to saturated fat than are [[cis]] fats in many respects, including the fact that they solidify at a lower temperature. [[Image:Linoleic acid.png|thumb|300px|Chemical structure of the polyunsaturated fat [[linoleic acid]].]] [[Image:Linoleic acid3D.png|thumb|300px|3D representation of [[linoleic acid]] in a bent [[Conformational isomerism|conformation]].]] A fatty acid has a [[carboxylic acid]] at one end and a [[methyl]] group at the other end. [[Carbon]] atoms in a fatty acid are identified by [[Greek alphabet|Greek letters]] on the basis of their distance from the carboxylic acid. The carbon atom closest to the carboxylic acid is the ''alpha'' carbon, the next adjacent carbon is the ''beta'' carbon, etc. In a long-chain fatty acid the carbon atom in the methyl group is called the ''omega'' carbon because ''omega'' is the last letter of the Greek alphabet. [[Omega-3 fatty acid]]s have a double bond three carbons away from the methyl carbon, whereas [[omega-6 fatty acid]]s have a double bond six carbons away from the methyl carbon. The illustration below shows the omega-6 fatty acid, [[linoleic acid]]. ==Health== === Benefits === Polyunsaturated fat, along with [[monounsaturated fat]] are "[[healthy fats]]," the amount of which in one's daily diet should be near 25 g (in a 2000 calorie-per-day diet).{{Fact|date=February 2007}} Polyunsaturated fat can be found mostly in [[grain]] products, fish and sea food ([[herring]], [[salmon]], [[mackerel]], [[halibut]]), [[soybeans]], and [[fish oil]]. Foods like [[mayonnaise]] and [[soft margarine]] may also be good sources, but nutritional facts can vary by style and brand. [[Omega-3 fatty acids]] in fish oil, [[fish]] and [[seafood]] lower the total amount of LDL in the blood, which can decrease the risk of [[cardiovascular disease]].<ref name=n3>{{cite web | author=National Institute of Health | url= http://www.nlm.nih.gov/medlineplus/print/druginfo/natural/patient-fishoil.html | title=Omega-3 fatty acids, fish oil, alpha-linolenic acid | accessyear=2006|accessdate=March 26| date= August 1, 2005}}</ref> [[Omega-6 fatty acids]] in [[sunflower oil]] and [[safflower oil]] also reduce the risk of cardiovascular disease, but can contribute to [[allergy|allergies]] and [[inflammation]]. {{Fact|date=February 2007}} ===Some Examples of Foods containing polyunsaturated fat=== * [[fish]] * [[cereal]] * [[whole grain]] [[wheat]] * [[peanut]] * [[butter]] * [[margarine]] * [[bananas]] * [[hemp seed]] === Relation to cancer === Some studies have shown that consuming high amounts of polyunsaturated fat may increase the risk of an individual developing [[cancer]].{{Fact|date=May 2007}} This is thought to be because polyunsaturated fat is prone to oxidation,<ref name=pmid_16477809>{{cite journal |author=Scislowski V, Bauchart D, Gruffat D, Laplaud PM, Durand D |title=Effect of dietary n-6 and n-3 polyunsaturated fatty acids on peroxidizability of lipoproteins in steers |journal=Lipids |volume=40 |issue=12 |pages=1245–56 |year=2005 |pmid=16477809 |doi=10.1007/s11745-005-1492-z}}</ref> <ref name=pmid_14962692>{{cite journal |author=Diniz YS, Cicogna AC, Padovani CR, Santana LS, Faine LA, Novelli EL |title=Diets rich in saturated and polyunsaturated fatty acids: metabolic shifting and cardiac health |journal=Nutrition |volume=20 |issue=2 |pages=230–4 |year=2004 |pmid=14962692 |doi=10.1016/j.nut.2003.10.012}}</ref> which leads to the generation of [[Radical (chemistry) | free radicals]] and eventually to [[rancidification|rancidity]]. Studies have shown that low dosages of [[Coenzyme Q10]] reduce this oxidation, and a combination of a diet rich in polyunsaturated fatty acids and [[Coenzyme Q10]] supplementation leads to a longer lifespan in rats<ref name=pmid_15036411>{{cite journal |author=Quiles JL, Ochoa JJ, Huertas JR, Mataix J |title=Coenzyme Q supplementation protects from age-related DNA double-strand breaks and increases lifespan in rats fed on a PUFA-rich diet |journal=Exp Gerontol. |volume=39 |issue=2 |pages=189–94 |year=2004 |pmid=15036411 |doi=10.1016/j.exger.2003.10.002}}</ref>. Studies on animals have shown a link between polyunsaturated fat and the incidence of tumours. In some of these studies the incidence of tumours increased with increasing intake of polyunsaturated fat, up to about 5% of total energy, near to the middle of the current dietary intake in humans. However, studies in humans have found little evidence of an association between polyunsaturated fat and the risk of cancer.{{Fact|date=March 2008}} It is advised that the level of polyunsaturated fats in the diet be regulated if [[Coenzyme Q10]] supplements are not being taken. However, even without [[Coenzyme Q10]] supplementation, the effect on health might be more beneficial than harmful in terms of its effect on reducing cholesterol levels. ==See also== *[[Monounsaturated fat]] * For listings of particular classes, see **[[Polyunsaturated fatty acid]] **[[Omega-3 fatty acid]] **[[Omega-6 fatty acid]] **[[Omega-9 fatty acid]] **[[Conjugated linoleic acid]] *[[Essential fatty acid]] - for biochemistry of most polyunsaturated fats *[[Essential fatty acid interactions]] - for the interactions between ω-6 and ω-3 fatty acids *[[Unsaturated fat]] ==References== <references /> ==External links== *[http://www.benbest.com/health/essfat.html#chem The Chemistry of Unsaturated Fats] [[Category:Fatty acids]] [[Category:Nutrition]] [[Category:Lipids]] [[da:Flerumættet fedtsyre]] [[ja:多不飽和脂肪酸]] [[no:Flerumettet fettsyre]] [[simple:Polyunsaturated fat]] [[fi:Monityydyttymätön rasvahappo]] [[pt:Gordura poliinsaturada]] [[sv:Fleromättat fett]] [[zh:多元不飽和脂肪]]