Talk:Lipid

message: Most of what I have seen counts cholesterol lipids, and this page in fact does so when it lists the hydrophobic and hydrophilic groups, but cholesterol is definitely not a fatty acid ester.
Jedi Dan, Cholesterol molecules are not lipids. They are actually a series of circular hydrocarbon molecules, each bonded together. I cant remember exactly what cholesterol looks like, but cholesterol and the steroid hormones derived from it typically have hydroxyl (OH), ketone/aldehyde (C=O) and methyl groups on them.
What he said is correct, assuming R1' to be a hydrocarbon chain (except the last carbon atom) and R2' to be a glycerol molecule, you could show it to be R1'-CO-O-R2' where the CO is a double bond. Check out the links below, they would probably explain better than I can in text.
Read more about steroid hormones/cholesterol at http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Cholesterol.html
Read more about triglycerides at http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/Fats.html
:*I too have generally thought cholesterol and steroids as not being "lipids".  However, the following passage appears in General Chemistry Online!: "lipid. A diverse group of organic molecules that contain long hydrocarbon chains or rings and are hydrophobic. Examples are fats, oils, waxes, and steroids." Likewise the Drug Discovery & Development Glossary states that a lipid is "an oil-soluble molecule such as a fatty acid or steroid." If on the other hand one looks at the IUPAC Nomenclature Recommendations, lipids and steroids are classed differently. Under IUPAC Nomenclature, lipids are a class of molecules that includes fatty acids, neutral fats, long-chain alcohols, long-chain bases, phospholipids, glycolipids and neuraminic acid.  Therefore, I'd say that "lipids include steroids when the term (lipid) is used in a colloquial sense; however, from an organic chemistry nomenclature point of view, steroids are formally excluded from the lipid-class of molecules."  Courtland 01:52, 2005 Mar 8 (UTC)
:*Here's a more concise view which is part of the IUPAC Glossary of Class Names, the Lipid entry, which goes into specifics of what is included in the class: http://www.chem.qmul.ac.uk/iupac/class/lipid.html.  Now this page says that the term lipid is "a loosely defined term for substances of biological origin that are soluble in nonpolar solvents. They consist of saponifiable lipids, such as  glycerides (fats and oils) and phospholipids, as well as nonsaponifiable lipids, principally steroids."  Therefore, steroids are lipids afterall and their separation in the IUPAC nomenclature does not indicate they are unrelated. Courtland 02:03, 2005 Mar 8 (UTC)
Sometimes categories can be incompletely congruent in different contexts. For example, cholesterol is always considered a lipid in a medical context, and this would be a common reason for a reader to look at this article. We need a section on cholesterol and other sterols explaining how they differ from triglycerides and in what contexts they are or are not considered lipids. alteripse 14:07, 24 December 2005 (UTC)
replies: text: No it doesn't, that's precisely what should be avoided.  The term is a vague one and there's not a lot any one person can do about that.  If one narrow definition is used, it will bias the article. Showjumpersam 20:26, 14 June 2007 (UTC)

text: What constitutes a small molecule is a semantic question. The molecular weight cut off for a small molecule is rather fuzzy, especially considering there are multiple definitions of a small molecule.  Using the drug definition of a small molecule (orally available), the upper limit is around 900, so using this definition,  a triglyceride could be considered at the upper range of a small molecule. An alternative biochemical definition of a small molecule is monomer whereas biopolymers (proteins, RNA and DNA polynucleotides, polysaccharides) would be considered "large" molecules. A triglyceride is consider an oligomer and hence would be at the borderline between small and large molecules. There are water soluble lipids such as fatty acids, but I agree most have low solubility in water. Boghog (talk) 11:56, 8 November 2015 (UTC)
thread_title:  ''Lipids are fatty acid esters...'' and cholesterol as lipid

message: Others have noticed that there is no general agreement on the term 'lipid'.  W. Christie's review What is a Lipid? is useful. Given that there are so many definitions out there, and that so many of them are vague, this article just needs to pick one, lay out its reasoning, make explicit what's ruled in or out, and note that there are other common definitions.  David.Throop 17:37, 5 January 2007 (UTC)
replies: text: No it doesn't, that's precisely what should be avoided.  The term is a vague one and there's not a lot any one person can do about that.  If one narrow definition is used, it will bias the article. Showjumpersam 20:26, 14 June 2007 (UTC)

text: What constitutes a small molecule is a semantic question. The molecular weight cut off for a small molecule is rather fuzzy, especially considering there are multiple definitions of a small molecule.  Using the drug definition of a small molecule (orally available), the upper limit is around 900, so using this definition,  a triglyceride could be considered at the upper range of a small molecule. An alternative biochemical definition of a small molecule is monomer whereas biopolymers (proteins, RNA and DNA polynucleotides, polysaccharides) would be considered "large" molecules. A triglyceride is consider an oligomer and hence would be at the borderline between small and large molecules. There are water soluble lipids such as fatty acids, but I agree most have low solubility in water. Boghog (talk) 11:56, 8 November 2015 (UTC)
thread_title: More 'What is a lipid?'

message: For laymen, the beginning of the article does not explain the relationship between lipids, fatty acids, and glycerides. The reason for the second section would make more sense if it did. However, it does a good job of explaining the relationship between lipids and fats.  Mdmcginn 19:48, 14 June 2007 (UTC)
thread_title: Lipids, fatty acids, and glycerides

message: You mean Amphiphilic right? I hope you dont mind if I make a few minor chances to make it more technically accurate.
Jedi Dan
Amphipathic and amphiphilic are both correct and both mean that the molecule is part hydrophobic and part hydrophilic. GFP 06:15, 16 June 2006 (UTC)
thread_title: Amphipathic? This makes no sense

message: and I thought this page should update to reflect... but don't have the time to do it now.
A quote	In the LIPID MAPS classification scheme, lipids are divided into eight primary categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterol lipids, prenol lipids, saccharolipids, and polyketides. These categories are based on the functional backbone of the lipid molecule from a chemical standpoint. The categories are further subdivided into classes and subclasses to handle the existing and emerging arrays of lipid structures.
Source:	
I'll check back later, but perhaps someone with more biology than I can start to take a whack at that.
JRice 21:28, 13 May 2005 (UTC)
thread_title: Lipids are in the news this week,

message: what is the primary physiological function of lipids:
a. provide absorbtion of fat soluble vitamins
b. conserve heat
c. provide material for synthesis of hormones
d. supply energy
???
How about e. all of the above? alteripse 03:37, 10 January 2006 (UTC)
replies: text: Actually those are all quite minor (the absorbtion of fat soluble vitamines is almost irrelevant, the body doesn't need fat in it's intake to do this...).  The major purpose is to build cellular membranes, followed closely by lipids as signalling molecules.  Showjumpersam 20:30, 14 June 2007 (UTC)
thread_title:  Question?  

message: I am a chemistry novice and am a bit confused by this article.  The intro says that
"Lipids are one class of aliphatic hydrocarbon-containing organic compounds,"
and in the 'Structure' section we have:
"Some lipids are linear aliphatic molecules, while others have ring structures. Some are aromatic, while others are not."
Okay so far, perhaps, but in the 'Aliphatic compounds' article we have:
"In chemistry, aliphatic compounds are non-aromatic organic compounds"
There appears to be a contradiction here which somebody could maybe resolve.
:Well, this all got quite mixed up. Aliphatic means not aromatic. Lipids are generally aliphatics, and the most popular (fatty acids, glycerides, etc.) are entirely aliphatic. But lipids can also have aromatic groups attached, for instance resorcilonic lipids, and they are then called alicyclic. Karol 12:46, 4 April 2006 (UTC)
replies: text: Makes much more sense. Thanks for the edit, Karol.  User:Kaplin 09:17, 5 April 2006 (UTC)

text: Sorry, but aliphatic does not mean 'not aromatic'.  Aliphatic refers to chains (which is usual for fatty acid residues) where aromatic refers to a particular type of delocalised pi system of electrons.  There is such a thing as anti-aromatic.  Colloquially, if a compound's primary functionality is aromatic, it will be referred to as such, but if it happens to contain a phenyl ring as a more minor piece of functionality it won't be referred to as aromatic as that would be misleading.  I expect this is where the confusion originally came from and is quite understandable.  Showjumpersam 20:36, 14 June 2007 (UTC)
thread_title:  Alpihatic, non-aromatic? 

message: This article's GA status has been revoked because it fails criterion 2. b. of 'What is a Good Article?', which states;
::(b) the citation of its sources using inline citations is required (this criterion is disputed by editors on Physics and Mathematics pages who have proposed a subject-specific guideline on citation, as well as some other editors — see talk page).
LuciferMorgan 01:04, 9 November 2006 (UTC)
thread_title:  Reasons for GA Delisting 

message: OMG this article is crap unencyclopedic
makes no sense —Preceding unsigned comment added by 203.27.153.35 (talk) 
:i agree.  i rewrote the intro but the whole article needs organization and work.  now that i'm on the topic, the phospholipid pages are also pretty abysmal.  considering how fundamental these molecules are to life this should really be a priority. Roadnottaken 20:19, 6 July 2007 (UTC)
thread_title:  i have no time to fix 

message: Is this useful? Tim Vickers (talk) 14:55, 11 July 2008 (UTC)
thread_title:  Lipid factor 

message: The KDO structure has 9-carbons. That is wrong it should have EIGHT since it is an octulosonic acid derived from a ketooctose. --kupirijo (talk) 00:48, 24 October 2008 (UTC)
replies: text: So you're saying that in the upper rings shown in red at :Image:Kdo2 lipidA.png the side chain should have 2 carbons, rather than three? Tim Vickers (talk) 15:23, 24 October 2008 (UTC)
replies: text: Yes --kupirijo (talk) 01:29, 25 October 2008 (UTC)

text: Is :Image:Kdo2-lipidA.png correct? Tim Vickers (talk) 15:30, 24 October 2008 (UTC)
replies: text: With respect to #carbons it looks OK. It is an octulosonic acid as you know. 5 in the ring + 1 carboxyl + 2 in the side chain you corrected. Thanks. --kupirijo (talk) 01:29, 25 October 2008 (UTC)
thread_title:  KDO structure is wrong 

message: The last paragraph of this article when I accessed it was highly dubious and tendentious. It promotes an argument which proceeds to conclusions that are not widely held, and used highly selective citations to support this. I think to be fair, these should either be removed or balanced with other information.
The claim that, "High fat intake contributes to increased risk of obesity, diabetes and atherosclerosis" is not well supported in the literature. Perhaps the Nutrition Source from the Harvard School of Public Health is a better source as it includes data from several large trials (which are conspicuously not cited here). The claim that high fat intake leads to increased risk of diabetes is supported by only a single paper which primarily assessed survey data from patients who were already obese and diabetic. Hardly evidence that a high fat diet increases risk of diabetes. 
I have removed this section as it is very poor information. The field of nutrition is highly contentious and Balkanized. The goal of wikipedia should be to present all sides of an issue. This paragraph does not achieve that, and in fact seems designed to promote one particular (and highly dubious) point of view, using unethical scholarship practices. Michaplot (talk) 23:05, 4 March 2009 (UTC)
replies: text: I've reverted your removal - please achieve conensus on this talk page before removing large parts of an article, and also please use an edit summary - otherwise it can look like vandalism. Pedro :  Chat   23:11, 4 March 2009 (UTC)
thread_title:  Diet and Saturated fats 

message: This last paragraph of this page makes me ashamed to promote wikipedia. It is nearly all bad. For example, the assertion that, "A substantial amount of scientific evidence supports the impact of dietary fatty acids on cardiovascular health.[29]" is apparently based on a single only moderately applicable paper from nearly 20 years ago. To cite a 20 year old paper in a rapidly advancing field to support a contested notion is mischief. It is inaccurate--and shameful.
The Nutrion Source (www.hsph.harvard.edu/nutritionsource) says:
     
"Eat a low-fat, low-cholesterol diet" has been the mantra for healthful eating for decades. Touted as a way to lose weight and prevent or control heart disease and other chronic conditions, millions of people have followed (or, more likely, have tried to follow) this advice. Seeing a tremendous marketing opportunity, food companies re-engineered thousands of foods to be lower in fat or fat free. The low-fat approach to eating may have made a difference for the occasional individual, but as a nation it hasn't helped us control weight or become healthier. In the 1960s, fats and oils supplied Americans with about 45 percent of their calories; (1) about 13 percent of us were obese and under 1 percent had type 2 diabetes, a serious weight-related condition. Today, Americans take in less fat, getting about 33 percent of calories from fats and oils; (1) yet 34 percent of us are obese and 8 percent have diabetes, most with type 2 diabetes. (4, 5)
Why hasn't cutting fat from the diet paid off as expected? Detailed research—much of it done at Harvard—shows that the total amount of fat in the diet isn't really linked with weight or disease. [emphasis mine]
I tried to remove this section but was prevented by Pedro. I was told to provide reasons here (which I had done) and then to get consensus. I contend that the health information in this article needs some attention. Does anyone agree?Michaplot (talk) 23:53, 4 March 2009 (UTC)
replies: text: Hi, Michaplot. I see your point regarding the paragraph in question, but deleting an entire large section is generally considered to be poor form unless it's completely unsalvageable (i.e., it is patent nonsense, or nearly so). A preferable approach would be for you to correct the shortcomings that you find. After all, if we simply deleted everything that was less than perfect here on Wikipedia, we wouldn't have much Wikipedia left! – ClockworkSoul 04:05, 5 March 2009 (UTC)
thread_title:  Evidence for impact of dietary fatty acids on cardiovascular health 

message: I propose to change the 4th paragraph of this section from:
"High fat intake contributes to increased risk of obesity,[44][45] diabetes[46][47] and atherosclerosis.[48]"
to:
The relationship between dietary fat intake and health is currently controversial. While a few studies indicate increased risk of obesity,[44][45] diabetes[46][47] and atherosclerosis[48], a number of very large studies, including the Women's Health Initiative Dietary Modification Trial, an eight year study of 49,000 women, the Nurses' Health Study and the Health Professionals Follow-up Study, reveal no such link. [refs below] None of these studies suggested any connection between percentage of calories from fat and risk of cancer, heart disease or weight gain. The Nutrion Source, a website maintained by the Department of Nutrition at tha Harvard School of Public Health, says, "Detailed research—much of it done at Harvard—shows that the total amount of fat in the diet isn't really linked with weight or disease." 
Beresford SA, Johnson KC, Ritenbaugh C, et al. Low-fat dietary pattern and risk of colorectal cancer: the Women's Health Initiative Randomized Controlled Dietary Modification Trial. JAMA. 2006; 295:643-54.
Howard BV, Manson JE, Stefanick ML, et al. Low-fat dietary pattern and weight change over 7 years: the Women's Health Initiative Dietary Modification Trial. JAMA. 2006; 295:39-49.
Howard BV, Van Horn L, Hsia J, et al. Low-fat dietary pattern and risk of cardiovascular disease: the Women's Health Initiative Randomized Controlled Dietary Modification Trial. JAMA. 2006; 295:655-66.
Michaplot (talk) 05:07, 12 May 2009 (UTC)
replies: text: Thanks much for your input, your suggested change sounds reasonable. I'll check out the refs and try to update that whole section to reflect current thinking, as suggested in the GA review. Sasata (talk) 06:45, 12 May 2009 (UTC)

text: Good to see you're looking after the page. I meant the Mustad et al ahterosclerosis paper, which compares three normal-level fat diets with differing fractions of saturated fat, so we would need another source to say that someone had found association between total fat intake and cardiovascular disease. I didn't realise you were using the intro rather than results section of the weigh-gain Women's health intiative study, so I wouldn't mind putting it back in. Narayanese (talk) 09:53, 23 May 2009 (UTC)

text: Thanks for you contributions, Narayanese. I have been suffering from the end of the semester crunch and have not had time to add anything to this. I think you are right, the references could be better. This is such a controversial issue in nutrition, which as Gary Taubes points out in his article in Science (The Soft Science of Dietary Fat--I can send yo a PDF if you don't have access) is a field (nutrition that is) that has become highly Balkanized. There are entrenched positions, and at least some data supporting nearly anything you want to claim. I do think it is important to represent all valid positions on this issue. Perhaps wikipedia needs a page on Dietary Fat, which could explain the various camps and their claims more fully. In the present article, I think that the "fat is bad" group should be mentioned, but my reading of the literature is that this position is not much supported. As the Nutrition Source strongly says, the largest and best studies have all indicated that quantity of fat is not (much) correlated with any health impact (fatty acid type is, of course). I suggest that this notion should be presented as the current state of the research. However, this goes against a large investment by some very powerful groups in the notion that dietary fat is bad, so it is bound to be controversial. It is a fine line between giving all sides equal time, and fairly representing the current state of research. I will hopefully have some more time for this when I finish with the semester.Michaplot (talk) 20:04, 3 June 2009 (UTC)
replies: text: I have access to Science and read the article, shuddered at the polarised debate. As for giving sides equal time, I wouldn't do that - better evidence and worse evidence shouldn't be presented as if they were equal. Narayanese (talk) 19:50, 4 June 2009 (UTC)
thread_title:  Proposed Changes to Nutrition and Health Section 

message: please give answer  —Preceding unsigned comment added by 86.41.158.30 (talk) 09:59, 25 May 2009 (UTC)
thread_title:  flash point smoke point and melting point 

message: Having just came to this page, there is a rather strange sentence at the top of the page which suggests there should be an image, however it appears to have been broken? My total inexperience with Wiki's makes it impossible for me to check for the problem myself, or fix it should it even exist.  —Preceding unsigned comment added by 62.31.182.37 (talk) 12:23, 2 November 2009 (UTC)
replies: text: Fixed. Sasata (talk) 13:43, 2 November 2009 (UTC)
thread_title: Image broken?

message: At the end of the article, an organization is described as:
:"Professional medical education organization for health care professionals who seek to prevent morbidity and mortality stemming from dyslipidemias and other cholesterol-related disorders."
In particular, the words "morbidity and mortality" seem to have been chosen to portray the group in a good light, with "Professional" adding to the effect. I don't have time at the moment to work on it, but I thought that I would point it out for someone else to work on. Aero-Plex (talk) 20:40, 2 October 2011 (UTC)
thread_title:  Word Choice 

message: Carotenoids have an important role in photosynthesis. They are isoprenes, lipids, and they are not mentioned in functions in this role.--Miguelferig (talk) 17:39, 2 May 2013 (UTC)
thread_title: Photosynthesis

message: In the second paragraph of the introduction, the phrase "Using this approach" is used without a clear reference to any previously mentioned method, unless it is referring to the division of lipids according to their subunits. Does anyone have the biochemical know-how to clarify this paragraph?Huscarlkarl (talk) 22:48, 22 August 2013 (UTC)
thread_title:  "This Approach"? 

message: * are Lipids include fat-soluble vitamins (such as vitamins A, D, E, and K)?
Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. 
:-P1ayer (talk) 03:18, 24 August 2013 (UTC)
thread_title:  Why? 

message: The citation style in this article has become somewhat inconsistent.  Previous versions used Vancouver style author format and these have become gradually replaced with  templates that use a Module:Citation/CS1 style authors and this change in style contravenes WP:CITEVAR. Also it should be pointed out that per this discussion, the use of  has become deprecated.  There are a number of options that could be used to overcome these shortcomings:
# Substitute all the  templates and optionally use list-defined references to reduce clutter.
# Add a  parameter to all the citations so that the author format in the rendered citations is consistent.
# Use  / templates that generate clean author meta-data while avoiding the overhead of explicit "first1, last1, first2, last2, ..." author parameters. See for example enzyme that uses  templates  throughout.
I have a script that can do any combination of these things to produce an internally consistent citation style. Thoughts? Boghog (talk) 14:50, 15 March 2015 (UTC)
thread_title:  Citations 

message: Large portions of this article seem to be copied from http://www.lipidmaps.org/resources/tutorials/lipid_tutorial.html#L. Should they be references as such? WhileNotTrue (talk) 11:21, 26 May 2016 (UTC)
thread_title:  Copy of Lipid Maps? 

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thread_title:  External links modified 

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thread_title:  External links modified 

message: Am I confused or stupid? In the the third sentence in the section on Energy Storage it states ″…carbohydrate carbons are all bounded to hydrogens unlike in carbohydrates.″ Should this read ″…triglyceride carbons are all bounded to hydrogens unlike in carbohydrates.″? Rayf 13:00, 1 June 2018 (UTC)
thread_title: Confused