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What are Antioxidants?


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  • 2 months later...

Hi there,


An antioxidant is a chemical that prevents the oxidation of other chemicals. In biological systems, the normal processes of oxidation (plus a minor contribution from ionizing radiation) produce highly reactive free radicals. These can readily react with and damage other molecules: in some cases the body uses this to fight infection. In other cases, the damage may be to the body’s own cells. The presence of extremely easily oxidisable compounds in the system can “mop up” free radicals before they damage other essential molecules.


Hope that that answers your question.




P.S - Sorry moderators about posting a link to my site on my previous two posts. The intention wasn't to spam :)

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  • 2 weeks later...

As the name implies, antioxidants are substances that are capable of counteracting the damaging, but normal, effects of the physiological process of oxidation in animal tissue. Antioxidants are nutrients (vitamins and minerals) as well as enzymes (proteins in your body that assist in chemical reactions). They are believed to play a role in preventing the development of such chronic diseases as cancer, heart disease, stroke, Alzheimer’s disease, Rheumatoid arthritis and cataracts.

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My question is the same as my topic-


What are antioxidants?

How it works, and what is its significance?

What is the best source of antioxidants?

Do their deficiency or excess cause serious troubles?


Try a search of the term "flavonoids". Class of antioxidants found in fruits, some vegetables, and chocolate. You will find there are many flavonoids, each thought to have specific value to the human biological system, and specific ones are found in specific source foods.


So enjoy chocolate (dark), but not in excess; it's rather fattening! imp

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Actually It's starting to look more and more unlikely that the beneficial effect derived from ingestion of anti-oxidants is due to their ability to absorb free-radicals. Or at least entirely due to this.

The premises that this is why they are good for you is purely derived from conjecture.

For example:


There is excellent evidence that eating fruits and vegetables is good for you.

Fruits and vegetables contain large amounts of anti-oxidants.

Thus eating large amounts of anti-oxidants must be good for you.

And anti-oxidants protect your body from harmful oxidation.


I'm pretty sure I'm not the only one who can see how seriously this logic is flawed.


Actually most studies done where people have ingested a large dose of a single anti-oxidant (usually a vitamin) have show either no health benefit or deleterious health effects. Vitamin E is a good example.


If I were to put my money on a beneficial effect for anti-oxidants I'd say that the health benefits derived from them is more so due to chemical genetic interaction.

For example:

Antioxidant A is structurally similar to Toxin B. This causes the body to respond by alteration of gene express to protect the body from Toxin B. However as Toxin B isn't present the observable effect from Antioxidant A is a health benefit. This is because it basically steps up the bodies defenses.


More evidence is gaining to support this second hypothesis. For example there is a powerful antioxidant Resveratrol found in wine which is believed to be partially responsible for the health benefit derived from red wine (though other compounds are now being shown to be equally if not more important). Studies have shown that daily doses of this anti-oxidant promote longevity in Yeast, mice, and drosophila. Also resveratrol has been show to be a regulator of mitochondrial proliferation.

Other work has linked the maintenance of mitochondria to longevity. Actually the expression of mitochondrial proteins and their integrity is very strongly linked to many health benefits. Also the inverse is true as well, where mitochondrial defects are show to be very deleterious.

And guess what's the natural function of Resveratrol? It's a Toxin. Well it's not toxic to us, it's an anti fungal present in the skins of fruits.


I think part of the problem occurs from the fact that we sloppily group all these compounds antioxidants; Which causes people to assume this antioxidant property is what's beneficial about these compounds. However there is really no evidence that they protect in such a manner in-vivo.


While the evidence is still very scarce about their actual mode of action. I feel pretty confidant in saying that I believe it is far more complex than that of a sponge for free radicals.

I cringe every time someone gives this explanation. As at most it can only be partial correct.


(Anti-oxidant proteins are a strong exception to what I've said however. I'm referring to small molecules here)

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Actually some antioxidants as selenium and mangenese are essential cofactors of proteins involved in oxidative stress response (I'd rather say that proteins are involved to prevent oxidative stress rather than being antioxidants, the latter might be misleading). This includes for instance superoxide-dismutases (in case of manganese) and glutathione peroxidases (withe a selenium center). Manganese does also counter oxidative stress all by its own, though one would need concentrations that are toxic to many organisms.

To complicate things, we got elements that are both causing oxidative stress, and are also involved in preventing it. For instance, iron can cause massive oxidative stress in presence of hydrogen peroxide (a common sideproduct of oxygen respiration) by formation of oxygen radicals by the Fenton reaction. However, some organisms actually use iron as a cofactor in superoxide-dismutase that are involved in detoxification.

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