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== Overview ==

[[File:Lecithin.png|right|300px]]
'''Lecithin''' is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues composed of [[phosphoric acid]], [[choline]], [[fatty acids]], [[glycerol]], [[glycolipid]]s, [[triglyceride]]s, and [[phospholipid]]s (e.g., [[phosphatidylcholine]], [[phosphatidylethanolamine]], and [[phosphatidylinositol]]).

Lecithin was first isolated in 1846 by the French chemist and pharmacist [[Theodore Nicolas Gobley|Theodore Gobley]].<ref>{{cite journal
 |last=Gobley |first=Theodore |year=1846
 |title=Recherches chimiques sur le jaune d'œuf |trans_title=Chemical researches on egg yolk
 |journal=Journal de Pharmacie et de Chemie |series=3rd series |volume=9 |pages=81–91
 |url=//books.google.com/books?id=DC04AAAAMAAJ&pg=PA84 |language=French}}</ref> In 1850, he named the phosphatidylcholine ''lécithine''.<ref>{{cite journal
 |last=Gobley |first=Theodore |year=1850
 |title=Recherches chemiques sur les œufs de carpe |trans_title=Chemical researches on carp eggs
 |journal=Journal de Pharmacie et de Chemie |series=3rd series |volume=17 |pages=401–430
 |url=//books.google.com/books?id=vQVCAAAAcAAJ&&pg=PA411 |language=French
 |quote=Je propose de donner au premier le nom de ''Lécithine'' (de λεκιθος, jaune d'œuf), parce qu'on le rencontre en grande quantité dans le jaune d'œuf...}}</ref> Gobley originally isolated lecithin from [[egg yolk]]&mdash;λέκιθος ''lekithos'' is "egg yolk" in [[Ancient Greek]]&mdash;and established the complete chemical formula of phosphatidylcholine in 1874;<ref>{{cite journal
 |title=Sur la lécithine et la cérébrine |year=1874 
 |first=Theodore |last=Gobley
 |journal=Journal de Pharmacie et de Chimie |series=4th series |volume=19 |pages=346–353
 |url=//books.google.com/books?id=ypdGAQAAMAAJ&pg=PA346 |language=French}}</ref> in between, he had demonstrated the presence of lecithin in a variety of biological matters, including venous blood, bile, human brain tissue, fish eggs, [[fish roe]], and chicken and sheep brain.

Lecithin can easily be extracted chemically (using [[hexane]], [[ethanol]], [[acetone]], [[petroleum ether]], [[benzene]], etc.) or mechanically. It is usually available from sources such as [[soy]]beans, eggs, milk, marine sources, [[rapeseed]], cottonseed, and sunflower. It has low solubility in water, but is an excellent [[emulsifier]]. In aqueous solution, its phospholipids can form either [[liposome]]s, bilayer sheets, [[micelle]]s, or lamellar structures, depending on hydration and temperature. This results in a type of [[surfactant]] that usually is classified as [[amphipathic]]. Lecithin is sold as a food supplement and for medical uses. In cooking, it is sometimes used as an emulsifier and to prevent sticking, for example in [[non-stick cooking spray|nonstick cooking spray]].

==Biology==
{{unsourced|section|date=February 2015}}
Lecithin, as a food additive, is also a dietary source of several active compounds: [[Choline]] and its metabolites are needed for several physiological purposes, including cell membrane signaling and cholinergic neurotransmission, and is a major source for methyl groups via its metabolite, [[trimethylglycine]] (betaine). [[Phosphatidylcholine]] occurs in all cellular organisms, being one of the major components of the phospholipid portion of the cell membrane.

While lecitihin is also a rich source of a variety of types of dietary fats, the small amounts of lecithin typically used for food additive purposes mean it is not a significant source of fats.

==Production==
Commercial lecithin, as used by food manufacturers, is a mixture of [[phospholipid]]s in [[Vegetable fats and oils|oil]]. The lecithin can be obtained by water degumming the extracted oil of seeds. It is a mixture of various phospholipids, and the composition depends on the origin of the lecithin. A major source of lecithin is [[soybean oil]]. Because of the [[European Union|EU]] requirement to declare additions of allergens in foods, in addition to regulations regarding [[genetically modified crops]], a gradual shift to other sources of lecithin (e.g., [[sunflower oil]]) is taking place. The main phospholipids in lecithin from soya and sunflower are [[phosphatidyl choline]], [[phosphatidyl inositol]], [[phosphatidyl ethanolamine]], and [[phosphatidic acid]]. They often are abbreviated to PC, PI, PE, and PA, respectively. Purified phospholipids are produced by companies commercially.

===Hydrolysed lecithin===
To modify the performance of lecithin to make it suitable for the product to which it is added, it may be hydrolysed enzymatically. In hydrolysed lecithins, a portion of the phospholipids have one fatty acid removed by [[phospholipase]]. Such phospholipids are called lysophospholipids. The most commonly used phospholipase is phospholipase A2, which removes the [[fatty acid]] at the C2 position of glycerol. Lecithins may also be modified by a process called [[fractionation]]. During this process, lecithin is mixed with an alcohol, usually [[ethanol]]. Some phospholipids, such as phosphatidylcholine, have good solubility in ethanol, whereas most other phospholipids do not dissolve well in ethanol. The ethanol is separated from the lecithin sludge, after which the ethanol is removed by evaporation to obtain a phosphatidylcholine-enriched lecithin fraction.

===Genetically modified crops as a source of lecithin===
As described above, lecithin is highly processed. Therefore, genetically modified (GM) [[protein]] or [[DNA]] from the original [[Genetically-modified crops|GM crop]] from which it is derived often is undetectable &ndash; in other words, it is not substantially different from lecithin derived from non-GM crops.<ref name=MarxDissertation>Gertruida M Marx, Dissertation submitted in fulfillment of requirements for the degree Doctor of Philosophy in the Faculty of Health Sciences, University of the Free State, South Africa. December 2010. [http://etd.uovs.ac.za/ETD-db/theses/available/etd-10042011-094627/unrestricted/MarxGM.pdf MONITORING OF GENETICALLY MODIFIED FOOD PRODUCTS IN SOUTH AFRICA]</ref> Nonetheless, consumer concerns about [[genetically modified food]] have extended to highly purified derivatives from GM food, such as lecithin.<ref name=Navigator>Staff, FoodNavigator.com, July 1, 2005.  [http://www.foodnavigator.com/Science-Nutrition/Danisco-emulsifier-to-subsitute-non-GM-soy-lecithin-as-demand-outstrips-supply Danisco emulsifier to substitute non-GM soy lecithin as demand outstrips supply]</ref> This concern led to policy and regulatory changes in the [[European Union]] in 2000, when Commission Regulation ([[European Commission|EC]]) 50/2000 was passed<ref>[http://eur-lex.europa.eu/smartapi/cgi/sga_doc?smartapi!celexapi!prod!CELEXnumdoc&lg=EN&numdoc=32000R0050&model=guichett Regulation (EC) 50/2000]</ref> which required [[Regulation_of_the_release_of_genetic_modified_organisms#Labeling_and_traceability|labelling of food containing additives derived from GMOs]], including lecithin. Because it is nearly impossible to detect the origin of derivatives such as lecithin, the European regulations require those who wish to sell lecithin in [[Europe]] to use a meticulous system of [[identity preservation]] (IP).<ref name=MarxDissertation /><ref>John Davison, Yves Bertheau (2007) [http://www.researchgate.net/publication/228628711_EU_regulations_on_the_traceability_and_detection_of_GMOs_difficulties_in_interpretation_implementation_and_compliance EU regulations on the traceability and detection of GMOs: difficulties in interpretation, implementation, and compliance] CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition, and Natural Resources 2(77)</ref>

==Properties and applications==
Lecithin has [[emulsion|emulsification]] and [[lubricant]] properties, and is a [[surfactant]]. It can be totally [[metabolism|metabolized]] (see [[Inositol]]) by humans, so is well tolerated by humans and [[nontoxic]] when ingested; some other emulsifiers can only be excreted via the [[kidney]]s.

The major components of commercial soybean-derived lecithin are:<ref>{{Citation |title=Composition of Soybean Lecithin |url=http://naldc.nal.usda.gov/download/26685/PDF |first=C.R. |last=Scholfield |journal=Journal of the American Oil Chemists' Society |volume=58 |number=10 |date=October 1981 |pages=889–892 |via=[[USDA]] |accessdate=2014-08-21 |doi=10.1007/bf02659652}}</ref>
* 33–35% Soybean oil
* 20–21% [[Inositol]] phosphatides
* 19–21% [[Phosphatidylcholine]]
* 8–20% [[Phosphatidylethanolamine]]
* 5–11% Other [[phosphatide]]s
* 5% Free [[carbohydrate]]s
* 2–5% [[Sterol]]s
* 1% Moisture

Lecithin is used for applications in human food, animal feed, pharmaceuticals, paints, and other industrial applications.

Applications include:
* In the [[pharmaceutical industry]], it acts as a wetting, stabilizing agent and a choline enrichment carrier, helps in emulsifications and encapsulation, and is a good dispersing agent. It can be used in manufacture of intravenous fat infusions and for therapeutic use.
* In [[compound feed|animal feed]], it enriches fat and protein and improves pelletization.
* In the [[paint]] industry, it forms protective coatings for surfaces with painting and [[printing ink]], has [[antioxidant]] properties, helps as a [[rust]] inhibitor, is a colour-intensifying agent, [[catalyst]], conditioning aid modifier, and dispersing aid; it is a good stabilizing and suspending agent, emulsifier, and [[wetting agent]], helps in maintaining uniform mixture of several [[pigment]]s, helps in grinding of [[metal oxide]] pigments, is a spreading and mixing aid, prevents hard settling of pigments, eliminates [[foam]] in water-based paints, and helps in fast dispersion of [[latex]]-based paints.
* Lecithin also may be used as a [[release agent]] for [[plastic]]s, an antisludge additive in motor lubricants, an antigumming agent in gasoline, and an emulsifier, spreading agent, and antioxidant in textile, rubber, and other industries.

===Food additive===
The nontoxicity of lecithin leads to its use with food, as an additive or in food preparation. It is used commercially in foods requiring a natural emulsifier or lubricant.

In confectionery, it reduces viscosity, replaces more expensive ingredients, controls sugar crystallization and the flow properties of [[chocolate]], helps in the homogeneous mixing of ingredients, improves shelf life for some products, and can be used as a coating. In emulsions and fat spreads, it stabilizes emulsions, reduces spattering during frying, improves texture of spreads and flavour release. In [[dough]]s and bakery, it reduces fat and egg requirements, helps even distribution of ingredients in dough, stabilizes [[fermentation (food)|fermentation]], increases volume, protects [[yeast]] cells in dough when frozen, and acts as a releasing agent to prevent sticking and simplify cleaning. It improves wetting properties of [[hydrophilic]] powders (e.g., low-fat proteins) and [[lipophilic]] powders (e.g., cocoa powder), controls dust, and helps complete dispersion in water.<ref name=applications>[http://www.ambujagroup.com/soya%20lecithin.asp Supplier's website with lecithin applications]</ref> Lecithin keeps [[Cocoa solids|cocoa]] and [[cocoa butter]] in a [[candy bar]] from separating. It can be used as a component of [[cooking spray]]s to prevent sticking and as a releasing agent. In margarines, especially those containing high levels of [[fat]] (>75%), lecithin is added as an 'antispattering' agent for shallow [[frying]].

Lecithin is approved by the [[United States]] [[Food and Drug Administration]] for [[human]] consumption with the status "[[generally recognized as safe]]".  Lecithin is admitted by the EU as a [[food additive]], designated as [[E number|E322]].  Research studies show soy-derived lecithin has significant effects on lowering serum [[cholesterol]] and [[triglyceride]]s, while increasing [[High-density lipoprotein|HDL]] ("good cholesterol") levels in the blood of rats.<ref>{{cite journal |author=Iwata T, Kimura Y, Tsutsumi K, Furukawa Y, Kimura S |title=The effect of various phospholipids on plasma lipoproteins and liver lipids in hypercholesterolemic rats |journal=J. Nutr. Sci. Vitaminol. |volume=39 |issue=1 |pages=63–71 |date=February 1993 |pmid=8509902 |doi=10.3177/jnsv.39.63 }}</ref><ref>{{cite journal |author=Jimenez MA, Scarino ML, Vignolini F, Mengheri E |title=Evidence that polyunsaturated lecithin induces a reduction in plasma cholesterol level and favorable changes in lipoprotein composition in hypercholesterolemic rats |journal=J. Nutr. |volume=120 |issue=7 |pages=659–67 |date=July 1990 |pmid=2366101 |url=http://jn.nutrition.org/cgi/pmidlookup?view=long&pmid=2366101}}</ref><ref>{{cite journal |author=Kaayla T. Daniel, PhD, CCN |title=Soy Lecithin: From Sludge to Profit |journal=Wise Traditions in Food, Farming, and the Healing Arts |volume=4 |issue=4 |date=Winter 2003 |url=http://www.westonaprice.org/soy-alert/694-soy-lecithin-from-sludge-to-profit.html}}</ref>

===Dietary supplement===
Because it contains [[phosphatidylcholine]]s, lecithin is a source of [[choline]], an essential nutrient.<ref name="Zeisel SH, da Costa KA 2009 615–23">{{cite journal |author=Zeisel SH |authorlink=Steven Zeisel |author2=da Costa KA |title=Choline: an essential nutrient for public health |journal=Nutrition Reviews |volume=67 |issue=11 |pages=615–23 |date=November 2009 |pmid=19906248 |pmc=2782876 |doi=10.1111/j.1753-4887.2009.00246.x}}</ref><ref name=AMR>Staff, Alternative Medicine Review (2002) [http://www.altmedrev.com/publications/7/2/150.pdf Phosphatidylcholine] Altern Med Rev. 7(2):150-4.</ref>  Clinical studies have shown benefit in acne, in improving liver function, and in lowering cholesterol, but clinical studies in dementia and dyskinesias have found no benefit.<ref name=AMR/><ref name=Altmedex>Jackie Dial, PhD and Sandoval Melim, PhD, ND.  June 2000, updated June 2003. "Lecithin" in AltMedDex® Evaluations. Truven Health Analytics.</ref><ref>Higgins JP, Flicker L. [http://www.ncbi.nlm.nih.gov/pubmed/12917896 Lecithin for dementia and cognitive impairment] Cochrane Database Syst Rev. 2003;(3):CD001015</ref> An earlier study using a small sample (20 men divided in 3 groups) did not detect statistically significant short term (2-4 weeks) effects on cholesterol in hyperlipidaemic men.<ref>Oosthuizen W, Vorster HH, Vermaak, WJ, et al. Lecithin has no effect on serum lipoprotein, plasma fibrinogen and macro molecular protein complex levels in hyperlipidaemic men in a double-blind controlled study. Eur J Clin Nutr. 1998;52:419-424.</ref>

[[La Leche League]] recommends its use to prevent blocked or plugged milk ducts which can lead to [[mastitis]] in breastfeeding women.<ref>[[Diane Wiessinger]], [[Diana West (lactation consultant)|Diana West]], and Teresa Pitman. [http://www.llli.org/docs/0000000000000001WAB/WAB_Tear_sheet_Toolkit/17_dealingwithplugsblebs.pdf Dealing with Plugs and Blebs] from Chapter 20, "Tear sheets"  in The Womanly Art of Breastfeeding. La Leche League. 2010. ISBN 0345518446</ref>

=== Compatibility with special diets ===
[[Egg (food)|Egg]]-derived lecithin is not usually a concern for those allergic to eggs since commercially available egg lecithin is highly purified and devoid of allergy-causing egg proteins.<ref>[http://www.aaaai.org/ask-the-expert/Parenteral-nutrition-in-an-egg-allergic-patient.aspx Discussion Forum: American Academy of Allergy, Asthama, and Immunology]</ref> Egg lecithin is not a concern for those on low-[[cholesterol]] diets, because the lecithin found in eggs markedly inhibits the absorption of the cholesterol contained in eggs.<ref>Unisci.com, [http://www.unisci.com/stories/20014/1029013.htm Why Eggs Don't Contribute Much Cholesterol To Diet.]</ref>

===Possible link to heart disease===
A growing body of evidence indicates lecithin is converted by [[gut bacteria]] into [[TMAO|trimethylamine-N-oxide]](TMAO), which is released into circulation, and may with time contribute to [[atherosclerosis]] and heart attacks.<ref>Wendy R Russell WR et al. (2013) [http://www.ncbi.nlm.nih.gov/pubmed/23880135 Colonic bacterial metabolites and human health (Review)]. Current Opinion in Microbiology 16(3):246–254</ref><ref>{{cite journal|last=Tang|first=WH|author2=Wang Z |author3=Levison BS |author4=Koeth RA |author5=Britt EB |author6=Fu X |author7=Wu Y |author8=Hazen SL |title=Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk.|journal=N Engl J Med.|date=Apr 25, 2013|pmid=23614584 |doi=10.1056/NEJMoa1109400 |pmc=3701945 |volume=368 |issue=17 |pages=1575–84}}</ref><ref>{{cite journal|last=Mendelsohn|first=AR|author2=Larrick JW |title=Dietary modification of the microbiome affects risk for cardiovascular disease.|journal=Rejuvenation Res.|date=Jun 2013|pmid=23656565|doi=10.1089/rej.2013.1447|volume=16|issue=3|pages=241–4}}</ref>

===Religious restrictions===
Soy-derived lecithin is considered by some to be ''[[kitniyot]]'' and prohibited on [[Passover]] for [[Ashkenazi Jews]] when many grain-based foods are forbidden, but not at other times. This does not necessarily affect [[Sephardi Jews]], who do not have the same restrictions on rice and ''kitniyot'' during ''Pesach''/Passover.<ref>(Reb Yehonatan Levy, Shomer Kashrut Mashgiach - based upon halachic rulings of CRC - Chicago Rabbinic Council, and from shiurim/lessons by Rabbi D. Raccah on "Pesach Preparations" following commentary from former Rishon-LeTzion Rav Ovadia Yosef). OK Kosher Certification, [http://www.okkosher.com/Content.asp?ID=172 Keeping Kosher for Pesach.] Retrieved on September 10, 2008.</ref>

[[Muslim]]s are not forbidden to eat lecithin ''per se''; however, since it may be derived from animal as well as plant sources, care must be taken to ensure this source is [[Halal#Dietary laws|halal]]. Lecithin derived from plants and egg yolks is permissible, as is that derived from animals slaughtered according to the rules of ''[[dhabihah]]''.<ref>Islamic Food and Nutrition Council of America FAQ, [http://www.ifanca.org/faq/#lecithin IFANCA: Consumer FAQ.] Retrieved on July 7, 2010. The practice of consuming Halal products is not widespread among Muslims, the practice is common with Muslims who follow Sharia laws.</ref>

== References ==
{{reflist|2}}

== External links ==
*[http://www2.chemie.uni-erlangen.de/services/dissonline/data/dissertation/Christoph_Wabel/html/Chapter1.html Introduction to Lecithin] ([[University of Erlangen]])
*[http://web.archive.org/web/20090117012303/http://www.cfsan.fda.gov/~dms/soyguid.html FDA Industry guideline for soy lecithin labeling] broken link
*[http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/pho_0288.shtml Phosphatidylcholine info]
*[http://www.kellymom.com/nutrition/vitamins/lecithin.html Use of lecithin for recurrent plugged ducts]
*[http://www.elma-eu.org European Lecithin Manufacturers Association official website]
*[http://ilps.org/ilps_main.htm The International Lecithin & Phospholipid Society Website]
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{{Nootropics}}
{{Cholinergics}}

[[Category:drug]]
[[Category:Food emulsifiers]]
[[Category:Phospholipids]]
[[Category:Membrane biology]]
[[Category:Nootropics]]
[[Category:Soy products]]
[[Category:Zwitterionic surfactants]]