Talk:Carotene

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Cancer risk[edit]

Shoul this statement "It has been shown in trials that the ingestion of beta carotene at about 30 mg/day increases the rate of lung cancer and prostate cancer" be changed to "It has been shown in trials that the ingestion of beta carotene at about 30 mg/day DECREASES the rate of lung cancer and prostate cancer" —Preceding unsigned comment added by 68.82.186.77 (talk) 12:45, 6 March 2008 (UTC)[reply]

That section does need reworked. See the next paragraph for the INCREASED risk of lung cancer in smokers. VMS Mosaic (talk) 15:48, 6 March 2008 (UTC)[reply]

(No title)[edit]

The two carotene chemical structures on this page (and related) are wrong. Two carbon atoms are missing from the conjugated central chain.

No, they're not (at least now). Icek 02:43, 25 October 2007 (UTC)[reply]

I just added two paragraphs: 1. the plant sources of beta-carotene 2. short comment on anti-oxidant properties and its use as a dietary supplement. -- Bedrupsbaneman 13:34, 8 Apr 2005 (UTC)

Carotene is the dimer of vitamin A. What does that mean? RickK 00:18 5 Jul 2003 (UTC)

A polymer is a molecule composed of several more or less identical copies of a simpler molecule. A dimer is a molecule composed of exactly two copies of a simpler molecule. The simpler molecule, in both instances, is termed a monomer. So carotene is a molecule composed of two joined copies of Vitamin A. -- Someone else 00:25 5 Jul 2003 (UTC)
Is there a link to dimer in the Wikipedia? If so, could it be added? If not, could it be explained in this article? I didn't have a clue. RickK 06:20 5 Jul 2003 (UTC)
Done. :) Bryan 06:37 5 Jul 2003 (UTC)
Thanks. Now I understand. RickK 22:15 5 Jul 2003 (UTC)

There are more than two forms of carotene. Changed to reflect that. NSiDms 13:54 11 Oct 2005 (UTC)

I've added in a reference about beta carotene and lung cancer Dr prune 12:23, 24 January 2006 (UTC)[reply]

Melissa's thought[edit]

I'm doing a science fair project on this and i need to know exactly what beta Carotene is

Wrong structure[edit]

I have changed the structures, as the old one was wrong. There should be 40 carbon atoms. In old structure (Image:Alpha-carotene.png) there were only 38. Compare it with structure from commons. Polimerek 23:20, 22 June 2006 (UTC)[reply]

- I think there is still a problem. Beta-carotene is supposed to have eleven double bonds and this one only has ten. Thejeffftrain 13:46, 08 Aug 2006

The structure is still wrong - it is missing two carbon atoms from the middle (look at the structure on the Bristol University link) Gingekerr 16:17, 29 October 2006 (UTC)[reply]

Beta Carotene, a pro vitamin?[edit]

Isn't beta carotene also called a "pro vitamin"? Can someone expand on "pro vitamins"? --68.103.154.140 16:49, 27 June 2006 (UTC)[reply]

It is a provitamin, and I added that fact with a link to the provitamin stub to the second paragraph of the article. A provitamin is a substance which animal tissues (particularly human) can convert into the corresponding vitamin. 71.205.13.162 06:51, 27 September 2006 (UTC)[reply]

Greek letters[edit]

Please write out the names of greek letters when they are first mentioned in ANY article. Thereafter we may use the shorthand. This is a general encyclopedia.

SMILES Notation[edit]

I was wondering if we should include the SMILES notation for the compounds in the article somewhere. It would be good to have them, but they tend to get pretty long in the long compounds. If anyone is wondering:

α-carotene: C\C2=C\CCC(C)(C)C2/C=CC(\C)=C\C=C\C(\C)=C\C=C\C=C(/C)\C=C\C=C(/C)\C=C\C1=C(/C)CCCC1(C)C

β-carotene: CC2(C)CCCC(\C)=C2\C=C\C(\C)=C\C=C\C(\C)=C\C=C\C=C(/C)\C=C\C=C(/C)\C=C\C1=C(/C)CCCC1(C)C

I'm not sure if these are correct, I generated them from the 2 diagrams on the page. If anyone wants the other notations, I can get them pretty easily. Sbrools (talk . contribs) 17:19, 6 May 2007 (UTC)[reply]


No adverse effects from common dietary sources[edit]

Why is this noteworthy at all? The bioavailability is about 1/6 compared to supplements, so the 20 mg/day studies would translate to more than 1.4 kg carrots per day. Icek 03:16, 25 October 2007 (UTC)[reply]

Well, the retinoid forms of vitamin A are pretty toxic.WolfKeeper 03:27, 25 October 2007 (UTC)[reply]
What has your answer to do with my question? This is about carotene, not about retinoids (and we know that production of retinoids from carotenes by the human body is regulated well enough not to result in retinoid toxicity in the relevant dosage (and even if this wouldn't be that way, your answer wouldn't make sense)). Icek 17:19, 25 October 2007 (UTC)[reply]
What has what you know to do with it? It's what is in the article that counts. Bioavailability varies anyway- if carotenes are eaten with a fatty meal, absorption is doubtless greatly increased. So your OR about 1.4 kg is probably out by a factor of up to 6. Carotenemia kicks in at about 60mg/day and I'm pretty sure that people with it don't have to eat that much more than 1.4 kg of carrots.WolfKeeper 17:37, 25 October 2007 (UTC)[reply]
The other point is that beta-carotene is often referred to as 'Vitamin A' and vitamin A is often referred to as toxic in large quantities. Compared to retinoids the toxicity is almost non existent.WolfKeeper 17:37, 25 October 2007 (UTC)[reply]
Even if beta-carotene is often referred to as 'Vitamin A' it isn't vitamin A, and vitamin A is not what the article is about (and I still don't know why you started talking about retinoid toxicity, but let's forget that and talk about the topic of this article). About the bioavailability see here, page 375ff: 2 mg oil-dissolved beta-carotene is 1 mg retinol equivalent, but it takes 12 mg dietary beta-carotene for 1 mg retinol equivalent. It is further noted that the bioavailablity of beta-carotene has long been overestimated by a factor of 2. But even if they are wrong, it's still 700 g of carrots.
That's about 3 big carrots. Sounds about right: http://www.dietitian.com/vitamina.html WolfKeeper 05:26, 28 October 2007 (UTC)[reply]
Do you have data on bioavailability from carrots when eaten with certain amounts of fat? Do you have data on how the people in the studies ate their carrots? Please cite your sources (also for the dosage necessary for carotenemia). Icek 20:03, 25 October 2007 (UTC)[reply]
You can tell just by looking at the numbers that they're very approximate. There's no way that the true figure is going to be a whole number like that. If I was trying to come up with a number for this, I would measure some stuff, and then deliberately pick a highly conservative number; and that's clearly what has happened. There's no prizes for being too low, people would get ill, but if you're too high, people just eat a few more bits of carrot.WolfKeeper 05:26, 28 October 2007 (UTC)[reply]
What's relevant is: Where's the study which actually shows that dietary beta-carotene does not have the known adverse effects at the relevant dosage? Icek 08:46, 28 October 2007 (UTC)[reply]

Dietary source: how much per kg?[edit]

Can someone please add how many mg per kg you can find in the veggies and fruits in the "dietary source" list. THANKS -- Michael Janich 03:21, 28 October 2007 (UTC)[reply]

Additionally, a certain concentration of carotene should be a criterion for inclusion in the list. I think it would be even better to use the amount of carotene per dry weight or per nutritional energy. Icek (talk) 12:05, 14 April 2008 (UTC)[reply]

WikiProject Food and drink Tagging[edit]

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partially cis vs. all-trans[edit]

I was wondering why the 3D stick model is cis at C6-C7 and C8-C9 (and not in C6'-C7' and C8'-C9') while the strucutral formula further down is all trans. If that is due to photo excitation it should be explained in the text. 2 September 2009 148.79.162.144

Me too - but I had to find [1] for the carbon labeling. Rod57 (talk) 15:55, 7 December 2010 (UTC)[reply]

Link to Whole Foods broken, New source required[edit]

The link should go to an archived version of the page unless it has simply been moved — Preceding unsigned comment added by 173.48.186.28 (talk) 15:39, 13 June 2014 (UTC)[reply]

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Two retinyl groups[edit]

Is it true that beta-carotene is composed of two retinyl groups? It says nothing about that on the beta-carotene page. Can someone explain that to me, please. Juliansteinb (talk) 17:50, 24 February 2019 (UTC)[reply]

Night Vision[edit]

When I was a youth I learned Carotene will help with night vision. Is this right? Jokem (talk) 03:10, 18 March 2024 (UTC)[reply]

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