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Thread: Antioxidants

  1. #1 Antioxidants 
    Forum Professor marcusclayman's Avatar
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    I don't know much about antioxidants, except that they prevent oxidation. I know most antioxidants have a usefullness to the body chemistry, other than to prevent oxidation, and that they are only put to use as antioxidents when theyre other use is satisfied.

    Such as betacarotene, less than 1/3 of the beta carotene you consume is converted to vitamin A, the rest is then used as an antioxidant. I'm not sure about others.


    Anyway, a discussion on sugars is turning into a discussion on antioxidants, so I thought a new thread is warrented

    If your like me, and not very familiar with antioxidants other than what people talk about, take a minute to read up

    http://en.wikipedia.org/wiki/Antioxidants

    According to the wiki, it turns out oxidation is usefull, to some unspecified degree. And we shouldn't (if we could) stop all oxidation.

    Also there are water soluble antioxidants as well as fat-soluble ones. The water soluble antioxidants protect cell cytosol and blood plasma, while the fat soluble antioxidants protect your cell membranes. Since they have different roles, excess of water soluble antioxidants, is not as good as a fair amount of each. However to determine how much is excess and how much is fair, one should probably look somewhere other than wikipedia.


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    Antioxidants would not interfere with oxidative processes that are necessary for life, the wiki isn't quite clear when they speak about oxidation being good.

    What the antioxidants primarily exist for is to remove harmful oxidation products from the cell. Such as superoxide, which is an unbound oxygen atom, or hydrogen peroxide. These products are necessary products of the regular function of life, unfortunately they like to react with anything willy-nilly so if they aren't taken care of they damage proteins, DNA, and membranes. So, we have antioxidants which preferentially react with these free radicals to minimize damage. It's not 100% effective as damage is known to build up in mitochondrial DNA over time. Of course, nothing biological is ever 100% effective.

    Edit: As far as I'm aware the value of dietary antioxidants isn't quite clear, the value of eating whole fruit and vegetables is clear though.


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  4. #3  
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    Alright I get it, so antioxidants don't prevent oxidation, they get rid of it's products, right?
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  5. #4  
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    They prevent oxidation by free radicals or highly oxidizing compounds like peroxide. Those free radicals and and oxidants are usually the products of other oxidization reactions which are necessary for life.

    So, yes in a sense they get rid of the products of oxidation, but that is in a sense also preventing oxidation.
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  6. #5  
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    For certain there are quack hucksters selling antioxidant pills. I remember a wave of them 15 years ago. Their reasoning was like "You can slow the body's decay, if you inject embalming fluid."

    The fad was driven by a cheap supply of pills and no regulation. The pills were cheap because they were empty (placebo) tablets. The "antioxidant" content was the preservative in the tablet bulk, normally present in any tablet. So it was like selling "medicinal gelatin" in the form of empty gel capsules. Of course there was no regulation on these pills.
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    Antioxidants does not directly control the process of aging, instead it aids in the regeneration of cells.
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    I have read some papers about free radicals triggering adaptation responses from the body which would have been or are prevented by the use of antioxidants. I believe free radicals were involved in the forming of memory, and the increase of blood flow to the muscles when exercising. Further antioxidants could hamper the beneficial effect of excercising as the body does not adapt the way it would do without the antioxidants. There is less need to adapt because there was less damage. But off course, this is not always a bad thing. Anyway in general, I believe this antioxidants to be beneficial, as can be found in the literature, but sidenotes as the above should be kept in mind.
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    Quote Originally Posted by i_feel_tiredsleepy
    Antioxidants would not interfere with oxidative processes that are necessary for life, the wiki isn't quite clear when they speak about oxidation being good.

    Oxidation is a double edged sword since the positive aspects pertain to such things as the respiratory burst from neutrophils. This is vitally important as a defense mechanism in the inflammatory response and against various types of microorganisms.
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  10. #9  
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    yeah, i think it's like what paracelsus said, 'dosage makes the poison'.

    Antioxidants may benefit health and prevent certain diseases like cancer but over-consumption is a concern. Vitamin E, a potent antioxidant combats free radicals, and toxic by-products from normal cellular metabolism which is good.

    However, some studies have reported that extreme consumption of vitamin E may impair muscular performance. Also, another study reported of an increased chance of stroke when high amount of vitamin E is consumed. So, beware!
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    An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules.The tea contains antioxidants.These are substances that may protect your cells against the effects of free radicals.I guess it depends on how long it takes all the chemicals to diffuse out of the teabag and equalize with the water.
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  12. #11 which part of the body?? 
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    so i skimmed through the text here, and searched a bit online, but nothing seems to turn up stating what produces antioxidants.

    i mean, we all know everything produces their own amount of AO but no one seems to be discussing their origins...

    if i've missed something here i apologize, there are way too much text floating around and i don't like reading mounds of duplicated text just to get nowhere slow, so i just skimmed...
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  13. #12  
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    @ typ911411and718

    They are produced by living things.
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  14. #13  
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    in reading the thread one could get very confused: it appears that antioxidants do prevent oxydation but they do not, or they prevent bad but not good oxidation.

    the question is pretty simple if you look at it from another point of view: there are substances (molecules) which can easily host an electron in excess by slightly changing their internal conformation and charge distribution.
    these molecules can be called "antioxydants" and we shall see why.

    many other molecules (such as oxygen radicals) are instead very unstable and reactive when they have an unpaired electron (missing or in excess), and to acquire a more stable conformation they will tend to avidly subtract an electron (oxydize) to compunds pretty stable such as proteins and lipids.
    these molecules may therefore produce significant cellular damage.

    some molecules of the first kind above (those we called "antioxydants") are used to get an electron from a molecule and give it afterwards to another one, and keep cycling this way:
    this kind of process makes it possible to oxydate glucose (the electrons are finally given to oxygen) in a controlled way and to extract the energy which is freed in the process to fuel the formation of ATP (the molecule which stores energy in the cell for its biochemical activities).
    this process is called "cellular respiration".

    many molecules of the same first kind (quinones and similar) can donate their electron to oxygen radicals (they get oxydized in the place of other precious molecules which would be damaged by oxydation) thereby annihilating the aggressive oxydizing power of such radicals; thus they are called "antioxydants".
    still, as it has been said before, they do not "prevent" oxydation: in general, they cycle, get oxydized and then in turn oxydize something else.
    the question is they do not do it in an "aggressive" way: they get the electron from radicals (counteracting their aggressiveness) and donate it to other molecules that can accept it without big problems.

    HOWEVER:
    - oxygen radicals MUST be formed in the process of cellular respiration.
    - oxygen avidity for electrons is what drives the whole story and makes life possible
    - oxygen avidity for electrons in the mean time drives it to assume those unstable conditions or combine with other atoms to form oxygen radicals
    - exogenous antioxydants may help calming down the oxydation turmoil, but to do that effectively they should reach the mitochondrion, where cellular respiration occurs and oxygen radicals are formed.
    - actually, almost none of the available antioxydants do reach the mitochondria.
    - antioxydants can sooth problems arising from oxygen radicals, outside mitochondria, and may therefore be useful in some pathologies
    - oxygen radicals such as NO can be actively produced by cells on demand, and are used to produce vasodilation and back-communication between neurons at synapses
    - leukocytes in particular can actively produce NO as a weapon against foreign cells, which can be killed by the oxydizing power of NO.

    in synthesis, antioxydant help keeping under control aggressively oxydizing molecules that cells ARE BOUND to produce but might be damaging. too bad the ones we assume with diet generally do not reach their true target (the mitochondrion)
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