Talk:Carbohydrate

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Contents

[edit] A clear definition?

On many pages of wikipedia, the first line is a simple, easy to understand definition of the term. Could someone put this on the article? CowsPoluteMoreThanCars (talk) 01:21, 17 December 2007 (UTC)

[edit] Structure of monosaccarides

Am I the only one thinking the glucose and fructose molecules look wrong. They seem to be correct empirically and based on their quantities of atoms. But the structure seems is not cyclic like most monosaccharides. Look at http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Carbohydrates.html for soem ideas on how to draw these molecules properly. I can draw them myself on paper quite well, but I usually find them difficult to do accurately on computer. I might scan in a few drawings of molecules ive got lying around when I find time, if anyone can find any use for them.

Also, when you say "but many important carbohydrates, like deoxyribose C5O4H10 have more hydrogen" you are technically wrong. The formular for ribose (if you look at the empirical formula you can see mine is consistent) is C5O5H(10). The thing about deoxyribose is, as the name suggests, an oxygen removed. Not hydrogen atoms.

"Carbohydrates consist almost exclusively of just three elements: carbon, hydrogen, and oxygen"

When you say this, 'almost' is perhaps a bad words. ALL carbohydrates are carbon, hydrogen and oxygen always. Glycoproteins and the like are not carbohydrates, so they are exempt from this rule. Pure carbohydrates, cellulose, glycogen, fructose, maltose, etc are all made from carbon, hydrogen and oxygen.

"The binding between the two sugars results in the loss of a hydrogen atom H from one molecule and a hydroxyl group from the other." This is essentually correct, it is known as a condensation reaction. I would edit this myself to add but I would rather not do so at this time, perhaps someone can fix this article.

I see there is a link to the nomenclature of carbohydrates. I personally think if this information was rewritten carefully here in an easy to understand and presentable form it would be very useful. I might undertake this myself later on, as I have this page bookmarked.

Jedi Dan Thanks for listening

Carbohydrates can change between ring form and straight-chain form. Hopefully the changes I have made address most of your complaints, except for the easy to understand bit, which I'm not a good enough writer to do. It would be helpful if someone went over them.

Typically, carbohydrates are classified into the sweet sugars (monosaccharides and disaccharides) and the unsweet, starchy, polysaccharides. Monosaccharides are simple, crystalline sugars. Disaccharides are composed of two monosaccharides joined together (hence di-saccharides). Polysaccharides are very large molecules such as starch or glycogen, which are formed from many monosaccharides joined together (poly-saccharides).

The characterization of monosaccharides as sweet and crystalline, and polysaccharides as unsweet and starchy is looking at only a few well-known examples. I don't think it can be worked into something which is generally valid.

[edit] "Carbs" boom

I expected there to be information on the sudden boom of "low-carb" diets in this article. Why isn't there? --Antoshi 20:19, 5 February 2006 (UTC)

Most likely because it does not have to do directly with information of Carbs, such as structure and uses, but you could probably add a link to it under the "see also" section. Matt White 23:42, 15 February 2006 (UTC)

[edit] Good article nomination

This article looks like it meets all the criteria, except that the section 'catabolism' doesn't really mean much at the moment, and needs to be expanded. Worldtraveller 10:47, 12 March 2006 (UTC)

[edit] Gigantic and totally unexplained contradiction

"Strictly speaking, carbohydrates are not necessary for human nutrition because proteins can be converted to carbohydrates. The traditional diet of some cultures consists of very little carbohydrate, and these people remain relatively healthy. ... Very low carbohydrate diets can slow down brain and neural function because the nervous system especially relies on glucose." How could both of these statements possibly be true? If someone knows anything about this, go ahead and fix it and don't focus on responding to me, because I'm probably going to forget about this. Tyharvey313

Well technically one could be very stupid and yet perfectly healthy. Servingsper 06:25, 17 April 2006 (UTC)

The information you're missing is that glucose can be synthesized from other molecules, just as you can get fat without eating any fat itself. See gluconeogenesis. —The preceding unsigned comment was added by Richard001 (talk • contribs) 03:44:51, August 19, 2007 (UTC).

[edit] Inappropriate picture/caption

The image of very REFINED grain foods (white bread, pasta, flour, sugar are pictured) is captioned: "Unrefined grain products are rich sources of complex carbohydrates". This should be changed to a more appropriate image I think..

[edit] Refined Carbohydrates

An explanation of what refined carbohydrates are has not been provided and does not exist elsewhere. I can't seem to find an in-depth explanation of this on the net so far... --MatthewKarlsen but edit as 81.86.122.174 (talk · contribs)

Did you check the sugar article? David D. (Talk) 15:40, 29 September 2006 (UTC)
I just did a quick check, they have a very good description of the differerences at the Sugar article. David D. (Talk) 15:45, 29 September 2006 (UTC)

[edit] Definition of "complex carbohydrate"

I'm not sure exactly what this term means. Sometimes it seems like carbohydrates are always caloric foods (starch, sugar, etc.) and that thus they all have the same calories per gram. Other times it seems like "complex carbohydrates" includes some fiber (or is entirely fiber) which implies it should have a lower calories per gram than simple carbohydrates. I can't tell if fiber is really a carb or not. Boris B 11:32, 27 November 2006 (UTC)

"Breads, pastas, beans, potatoes, bran, rice and cereals are all high in carbohydrates." This is doubtless true, but these all seem to be low (or moderate?) in simple carbohydrate content. Was this sentence written with a definition of carbohydrate which doesn't include sugars, or could the sentence be modified to include candy, dessert pastries, and many sodas? I'm just fumbling toward a consistent working definition of "carbohydrate" here (i.e. including sugars or not, including fiber or not). Boris B 19:50, 27 November 2006 (UTC)

The article certainly does not clarify the definitions of complex carbohydrates well. In answer to some of your specific questions, sugars, starches, and fiber are all definitely carbohydrates. There is no ambiguity there (although in some circles the term is used in non-technical ways to excluded fiber or other types of carbohydrates).
The term complex carbohydrate, to the extent that I have seen, is used in all of the following senses.
1) Any carbohydrate other than simple sugars.
2) Fiber
3) A group of carbohydrates that includes fiber (e.g. if a slice of bread has a lot of fiber in addition to the starch it is often said to have only complex carbohydrates whereas white bread does not).
4) Any carbohydrate or group of carbohydrates that has a low glycemic index (although how low depends on the source).
I believe in scientific discussion the first one would be considered the most "proper" definition although it is common for doctors to use the other definitions in many settings. The reason for the lack of clarity, as I understand it, is that at one time doctors believed that simple sugars were the only "bad" carbohydrates, so "complex carbohydrates" (which include starch and fiber) came to be synonymous with "good carbohydrates." Now it is recognized that some starches can be as bad or worse than sugar so, rather than admit they were wrong, some doctors and nutritionists have quietly altered how they use the term to fit the original intention of what they were trying to describe.
--Mcorazao 17:40, 5 December 2006 (UTC)

[edit] Necessitating the use of fat in energy production?

I have a problem with this sentence in the Nutrition section of the article: "Proteins and fat are vital building components for body tissue and cells, and thus it could be considered advisable not to deplete such resources by necessitating their use in energy production." With the latter part of it, to be specific. According to what I read on cell metabolism, cells make energy by burning sugar, fat and oxygen or - in the absence of oxygen - by burning just sugar. This latter process is (if I understood correctly) used either for very brief periods of time or merely to supplement the first process. So fat is pretty much ALWAYS used for energy. So, while the second part of the sentence makes perfect sense when we're talking about proteins, it seems like a silly thing to say about fat. Daelyn 21:24, 5 February 2007 (UTC)

Your conclusion "So fat is pretty much ALWAYS used for energy" is false and I don't see why you think it follows from the other things you said, which I think are accurate. Fat is used to form cell membranes. Because the brain is composed of a lot of long, thin connections, a large percentage of the mass of the brain is composed of cell membrane, and the healthy functioning of these membranes is important to brain function. Deficiency of omega-3 fats can lead to mental illness -- not because these fats are sometimes used to burn energy. They're an important component of cell membranes. Fats are also used to form many other substances such as hormones and eicosanoids. Burning them for energy is only one of their uses in the body.
The recommendation seems illogical to me: since fats are essential components of the body, to avoid necessitating their burning as energy, and therefore to eat a large percentage of carbohydrates, which cannot be used as components of the body. That seems all wrong to me. It's like saying that water is very valuable because it's so healthy so we shouldn't waste it by drinking it but should drink juice instead. It would make sense to have a minimum percentage of the diet as fats, and a minimum percentage as protein for use as a building block plus an additional percentage as either protein or carbohydrates for use as brain energy; I see no obvious need for any minimum carbohydrate intake, unless one makes the argument that using protein for energy leaves too much nitrogen to be excreted, and in that case the minimum carbohydrate intake should be just enough to provide energy for the brain -- much less than half the diet. Note Udo Erasmus' recommendations [1]; his food pyramids focus on a larger percentage of (healthy kinds of) fat, and he claims many benefits of this diet. --Coppertwig 12:38, 17 February 2007 (UTC)
I changed it to "and are also a source of energy for the body." --Coppertwig (talk) 18:36, 26 December 2007 (UTC)

[edit] Insulin index

I'm not sure that this recently added sentence is true: "This [simplistic] system assumes that high glycaemic index foods and low glycaemic index foods can be mixed to make the intake of high glycaemic foods more acceptable.". I deleted the word "simplistic" as being POV. If true, this should at least be explained more fully and supported with references on the insulin index page, and perhaps moved to that page rather than stated here. How does the amount of a food affect insulin response? Would adding a slice of bread to a piece of pie make the pie more acceptable according to this system, or would you have to replace half the piece of pie with half the slice of bread to get a benefit? --Coppertwig 12:24, 17 February 2007 (UTC)

[edit] carbohydrates as non-essential nutrients

Sorry, but carbohydrates are essential, since if you tried using only fat and/or protein for energy, you will eventually become quite sick (or worse). On paper it looks like protein has a lot of energy but in practice it's not a very efficient way to get energy. This part of the article really needs to be cleaned up because it is misinformation. By the way, Coppertwig above mentions something about "just enough carbs to power the brain". How the heck do you measure the exact amount your brain needs? Sounds like a whole lotta silliness to me.—The preceding unsigned comment was added by 207.161.43.153 (talk) 21:21, 6 March 2007 (UTC).

Carbohydrates are not essential nutrients as I have clarified above, and there are certainly scientific ways of measuring the glucose your brain needs. Richard001 03:51, 19 August 2007 (UTC)
Are you a scientist, Richard001? How do you know carbs are not essential? For a healthy person, sure, maybe not, but for a well-functioning person, carbs are very needed. Protein does not make enough glucose to supplement cutting carbs out entirely. Low glucose equals lower brain function and nervous system problems. So, while a person will be perfectly physically fit, they'll be as stupid as Paris Hilton and as jittery as a mental patient! Health is not just physical as mental health is much more important than physical health. No-carb diets kill people or at least incapacitate them if they keep up the regimen for years.PokeHomsar (talk) 21:29, 28 February 2008 (UTC)
Well, I am a scientist. The definition of an essential nutrient is one that cannot be synthesized by the body, which carbohydrates based on glucose certainly can. – ClockworkSoul 04:33, 29 February 2008 (UTC)
Well, that may be well and good, but so can Vitamin D and it's on the essential nutrient page. Every time you go outside, your body produces Vitamin D as a by-product of your fat cells interacting with UV rays. Why is it on the list then? There is a disease for lack of Vitamin D, called Rickets, which denotes that the body may produce Vitamin D, but not enough to keep one healthy. Same goes for glucose, especially if someone doesn't eat too many proteins and no carbohydrates, as protein is needed to produce the synthesized glucose. Of course, carbohydrates are a better resource for glucose than protein and produce more of it per gram. Glucose isn't made in the body unless protein is put into it or your body breaks down your muscles for lack of it. While I may have been somewhat mean, I'll give you that, but I was only mean to Paris Hilton, who deserves to be made fun of for her stupidity. No one can argue that she's stupid.PokeHomsar (talk) 00:05, 1 March 2008 (UTC)
That's true, for people who have regular year-round access to sufficient sunlight. Many, many, many people don't, especially those in temperate climates who have to endure winters under layers of clothing or those who work evening shifts. For these people, because they cannot synthesize it, vitamin D is indeed an essential nutrient. That's why in many locales many foods are vitamin D fortified. The metabolic result, of nearly all foods, however, is pyruvate, with which the body can fairly easily either synthesize glucose or generate energy. An otherwise complete diet that happens to be low in carbohydrates – such as the one that some native peoples have survived on for millenia – supplies more than enough metabolic fuel to maintain health. – ClockworkSoul 04:37, 1 March 2008 (UTC)
Why do you keep mentioning Paris Hilton? And I agree with CWS. David D. (Talk) 05:04, 1 March 2008 (UTC)

[edit] Octose?

Is there any monosaccharide containing 8 or more carbons? I don't know if it at all exist. In case, it does not exist, the nomenclature where 'triose, tetrose, pentose, hexose and so on' is reported, it is better to complete the sequence just by adding 'heptose' in stead of 'so on'. —The preceding unsigned comment was added by Nprasunpriya (talk • contribs) 02:34, 8 April 2007 (UTC).

  • The nomenclature is right, and there's certainly nothing preventing an octose from existing. I know of no such naturally occurring molecules, however, but that's not to say that they don't exist. – ClockworkSoul 12:53, 9 April 2007 (UTC)
The size of the carbon skeleton ranges from 3 to 7 carbons long, so octose would have to be artificially synthesized, if possible, which I suppose it would be. Richard001 01:07, 19 August 2007 (UTC)
Actually, I could be wrong (see monosaccharide). I'm not sure if the red links are natural or synthetic. Anything over seven would be extremely rare though. Richard001 04:42, 19 August 2007 (UTC)

There are longer sugars: eight carbon ones include keto-deoxyoctulosonic acid (KdO), which is found in most gram negative bacteria, and N-acetylneuraminic acid (sialic acid) a nine carbon sugar found in most higher organisms (and many lower organisms). —Preceding unsigned comment added by Spencerw (talk • contribs) 03:43, 11 October 2007 (UTC)

Doh - sialic acid, of course. That's a textbook example. Thank you. – ClockworkSoul 04:26, 29 February 2008 (UTC)

[edit] on hydrocarbons and carbohydrates

Obviously, both contain carbon and hydrogen. What is the difference? Is one a subset of the other? Do they have different Other Ingredients?

True hydrocarbons contain only carbon and hydrogen. Carbohydrates contain oxygen as well, although not all compounds of carbon, hydrogen, and oxygen are carbohydrates. Cjh57 01:42, 15 June 2007 (UTC)
"Hydrate" does not mean "containing hydrogen;" it means "containing water." The formula for a carbohydrate is [C(H2O)]n, meaning that CH2O, C2(H2O)2, C3(H2O)3, etc., are all valid carbs, whereas HCOCl would not be a valid carb even though it has H, C, and O. Kildon 06:05, 28 August 2007 (UTC)

[edit] Exact definition of carbohydrates

Some say it may contain C, H, O in any proportion. Others say that H and O must follow a 2:1 ratio. Others say that C:H:O = 1:2:1 (e.g. this page as is currently)


—-In this page with the '1:2:1' i think it is talking about unmodified monosaccharides which are, of course, not the same as carbohydrates at all. Deoxyribose (C5H10O4)seems to be just as much a carbohydrate as ribose.

Also the page Sugar Alcohol says that sugar alcohols (e.g. glycerol, sorbitol) are carbohydrates which seems perfectly reasonable to me (though i'm not a graduate chemist) as no part of carbo-hydrate seems to suggest etymologically anything about aldehydes or ketones. But then what are the differences between alcohols, sugar alcohols and carbohydrates?218.214.49.175 04:15, 18 August 2007 (UTC)

P.S. a lot of the bit about nutrition seems really quite bad and the claims really need to cited if not removed i think. That section needs a serious review. "and thus it could be considered advisable" ahem ahem and this is relevant why? this is not meant to be an essay on why people should stop eating carbs and veges. I think it's inadvisable for you to advise people what not to eat without something to back it up.218.214.49.175 04:15, 18 August 2007 (UTC)

[edit] help plz

can any one give any easily understandable info on this subject, because whats given is a little hard to understand......Thanks!!! :) —Preceding unsigned comment added by 76.184.131.96 (talk) 23:44, 23 September 2007 (UTC)

Well, who are we talking to for a start? If you know nothing about biology it will probably require a bit more effort. Richard001 07:14, 24 September 2007 (UTC)
Well, I was simply looking for information on Carbs and how to eat healthy, didn't know I need to do a degree in Biology to try and eat healthy. Silly me ! —Preceding unsigned comment added by 193.120.46.4 (talk) 11:19, 10 March 2008 (UTC)
The article as it's currently written is mostly a description what what carbohydrates are. As for their nutritional aspects, there is a Carbohydrate#Nutrition section that doesn't required you know the biochemistry. That part, however, needs some work. – ClockworkSoul 11:26, 10 March 2008 (UTC)
Thank you, just what i was looking for. —Preceding unsigned comment added by 193.120.46.4 (talk) 11:48, 10 March 2008 (UTC)

[edit] Formaldehyde

is formaldehyde(CH2O) a carb? —Preceding unsigned comment added by 202.161.1.167 (talk) 06:53, 13 October 2007 (UTC)

Nope, use Ctrl + F and you'll see this is mentioned in the lead. Richard001 08:14, 13 October 2007 (UTC)

[edit] Very Akward Pictures.

I would much appreciate if someone attached the traditional Hexagon representation of Hexoses. —Preceding unsigned comment added by Nassimo (talk • contribs) 19:01, 8 May 2008 (UTC)

I've added an animation showing the interconversion. Tim Vickers (talk) 19:41, 8 May 2008 (UTC)