Phytosterol
1862004
221537884
2008-06-24T23:13:32Z
MAlvis
86878
/* Lowering cholesterol */ Filled in title
[[Image:Sitosterol structure.svg|thumb|right|250px|β-sitosterol]]
[[Image:Ergosterol structure.svg|thumb|right|250px|[[Ergosterol]].]]
'''Phytosterols''' (also called '''plant sterols''') are a group of [[sterol|steroid alcohols]], [[phytochemical]]s naturally occurring in [[plants]]. They are white powders with mild, characteristic odor, insoluble in water and soluble in [[alcohols]]. They have many applications as [[food additive]]s, and in [[medicine]] and [[cosmetics]].
==Specific phytosterols==
[[Image:Steroid-nomenclature.png|thumb|right|250px|Nomenclature for steroid skeleton.]]
* The molecule shown at the top of the page is [[β-sitosterol]].
* By removing carbon 24<sup>2</sup>, campesterol is obtained.
* By removing carbons 24<sup>1</sup> and 24<sup>2</sup>, [[cholesterol]] is obtained.
* Removing a hydrogen from carbons 22 and 23 yields [[stigmasterol]] (stigmasta-5,22-dien-3β-ol).
* Removing carbon 24<sup>2</sup> and hydrogens from carbons 22 and 23 yields [[brassicasterol]] (ergosta-5,22-dien-3β-ol).
* Further removal of hydrogens from carbons 7 and 8 from brassicasterol yields [[ergosterol]] (ergosta-5,7,22-trien-3β-ol).
==Uses==
===Plant structure===
Plants contain a range of phytosterols. They act as a structural component in the [[cell membrane]], a role which in [[mammal]]ian cells is played by [[cholesterol]].
===Detection of organic matter===
Due to its presence in terrestrial plant matter and only rare occurrence in unicellar algae, β-sitosterol can be used as a [[biomarker]] indicating the amount of terrestrially derived organic matter present in a sample. As these [[sterols]] are generally insoluble in water, they will [[liquid-liquid extraction|partition]] onto suspended or settled solid matter (e.g. sediments). Due to [[grain surface area]] effects, [[mud]]s will have greater concentrations by weight than [[sand]]s or coarser grained sediments. To overcome this effect, ratios of individual sterols to total sterol content or [[cholesterol]] are usually used to indicate [[organic matter]] source.
===Detection of adulteration===
Presence of brassicasterol, together with auxiliary markers [[alpha-linolenic acid|α-linolenic acid]] and [[erucic acid]], is a marker of [[adulteration]] of [[soybean oil]] and [[sunflower oil]] with [[rapeseed oil]]. As there is no brassicasterol in sunflower and soybean oil, but its concentration in rapeseed oil is about 1400 mg/kg, the amount of rapeseed oil added can be calculated. [http://www.vupp.cz/envupp/falsificat.htm]
===Lowering cholesterol===
As a food ingredient or additive, phytosterols have cholesterol-lowering properties (reducing cholesterol absorption in intestines),<ref>{{cite journal | author=Ostlund RE, Racette, SB, and Stenson WF | title=Inhibition of cholesterol absorption by phytosterol-replete wheat germ compared with phytosterol-depleted wheat germ| journal=Am J Clin Nutr| year=2003 | pages=1385–1589 | volume=77 | issue=6 }}</ref> and may act in cancer prevention.<ref name="DeStefani">{{cite journal| journal = Nutrition and Cancer| volume = 37| issue = 2| year = 2000| pages =140–144| title = Plant Sterols and Risk of Stomach Cancer: A Case-Control Study in Uruguay| last = De Stefani| first = Eduardo, et al| url = | format = | accessdate =| doi = 10.1207/S15327914NC372_4 }}</ref> Phytosterols occur naturally in small quantities in vegetable oils, especially [[sea buckthorn oil]] (1640mg/100g oil),<ref>{{cite journal
| last = Li
| first = Thomas S. C.
| authorlink =
| coauthors = Beveridge, Thomas H.J., Drover, John C.G.
| title = Phytosterol content of sea buckthorn (Hippophae rhamnoides L.) seed oil: Extraction and identification
| journal = [[Elsevier|Food Chemistry]]
| volume = 101
| issue = 4
| pages = 1633–1639
| publisher = [[Elsevier]]
| date = 1633-1639
| url = http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6R-4JXH3RX-1&_user=10&_coverDate=12%2F31%2F2007&_alid=492322537&_rdoc=4&_fmt=summary&_orig=search&_cdi=5037&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=aacf572d9fa84a531c8ff224ca41fefb
| doi = 10.1016/j.foodchem.2006.04.033
| id =
| accessdate = 2006-11-20}}</ref> [[corn oil]] (968mg/100g),<ref>Pennington & Douglas, ''Food Values of Portions Commonly Used'', 18th ed. (2005)</ref> and [[soybean oil]] (327mg/100g oil).<ref>{{cite web
| last =
| first =
| authorlink =
| coauthors =
| title = The Marketing Edge: Phytosterols Qualisoy
| work =
| publisher = Qualisoy
| date =
| url = http://www.talksoy.com/pdfs/2006OilsBrochure.pdf
| format = Brochure (PDF)
| doi =
| accessdate = 2006-11-20}}</ref> One such phytosterol complex, isolated from vegetable oil, is [[cholestatin]], composed of campesterol, stigmasterol, and brassicasterol, and is marketed as a [[dietary supplement]]. Sterols can reduce cholesterol in human subjects by up to 15%.<ref>
{{cite journal
| coauthors = Marie-Pierre St-Onge, Benoit Lamarche, Jean-Francois Mauger, Peter J. H. Jones.
| title = Consumption of a Functional Oil Rich in Phytosterols and Medium-Chain Triglyceride Oil Improves Plasma Lipid profiles in Men
| journal = Journal Of Nutrition
| issue = 133
| pages = 1815–1820
| url = http://jn.nutrition.org/cgi/reprint/133/6/1815
| format = Article (PDF)
}}
</ref>
The mechanism behind phytosterols and the lowering of cholesterol occurs as follows: the incorporation of cholesterol into [[micelle]]s in the [[gastrointestinal tract]] is inhibited, decreasing the overall amount of cholesterol absorbed. This may in turn help to control body total cholesterol levels, as well as modify HDL, LDL and TAG levels. Many [[margarine]]s, [[butter]]s, [[breakfast cereal]]s and spreads are now enriched with phytosterols and marketed towards people wishing to lower their cholesterol levels.
However, caution about phytosterols is warranted. The actual health concern is [[atherosclerosis]] and the [[vulnerable plaque]]s which produce [[heart attacks]], most [[stroke]]s, etc. and evidence does not exist that lowering total blood cholesterol levels by any means is healthy. I.e. there are no large clinical trials which verify the efficacy of phytosterols in reducing heart attack rates and there is some evidence that phytosterols promote atherosclerosis, at least for some individuals<ref>
{{cite journal
| last = Patel, MD
| first =
| authorlink =
| coauthors = Thompson PD
| title = Phytosterols and Atherosclerosis
| journal = Atherosclerosis
| volume = 2006 May;186(1):12-9
| issue =
| pages =
| publisher =
| location =
| date =
| url = http://www.ncbi.nlm.nih.gov/pubmed/16325823?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_RVAbstractPlus
| doi =
| id =
| accessdate = }}
</ref>.
==References==
{{Reflist}}
==External links==
* [http://www.springboard4health.com/notebook/health_cholestatin.html Detailed Scientific Study of Dietary Phytosterols and the Effect on Cholesterol (Degussa)]
*[http://www.dietaryfiberfood.com/cholesterol-low.php Phytosterol content in food]
{{Sterols}}
[[Category:Steroids]]
[[Category:Sterols]]
[[Category:Food additives]]
[[Category:Phytochemicals]]
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