Talk:Antioxidant

Glutathione Levels

The values for glutathione levels in serum, provided in the table are wildly off. Normal values are as much as a hundred times less than the value in the chart, at ~3-6uM. See http://www.ncbi.nlm.nih.gov/pubmed/8353942 and http://www.circ.ahajournals.org/cgi/reprint/100/22/2244 for references. —Preceding unsigned comment added by 70.233.173.122 (talk) 11:08, 10 March 2009 (UTC)

Yes, those references do give a very different value than the reference I quoted and the new value agrees better with the Meister Annual review that states "micromolar levels are found in blood plasma". I've substituted one of the references you cited. Thanks for finding this mistake. Tim Vickers (talk) 15:18, 10 March 2009 (UTC)

Unreferenced table

The new table in the section on "Measurement and levels in food" is unreferenced. I can't find any evidence in the literature that eating eggs or milk actually changes the levels of glutathione or melatonin in the body. Unless this material is referenced with a reliable source that establishes the link with antioxidants, this material does not belong in the article about antioxidants. Tim Vickers (talk) 16:17, 26 May 2009 (UTC)

I found a source that discusses this (link to full text) PMID 15213035. A low-protein diet produces a transient change in serum GSH, but this is restored after a few days when the body adapts. Tim Vickers (talk) 19:58, 26 May 2009 (UTC)

Antioxidant compounds	Foods provide highest level of these antioxidants' building block[citation needed]
Glutathione	Milk, Cheese, Egg (methionine, precursor of cysteine), Whey Protein
Melatonin	Milk, Cheese (Tryptophan, precursor of serotonin)

Curious effects of ACE inhibition on EC-SOD (SOD3)

Both the inhibitor and the angiotensin receptor blocker seem to drastically upregulate the antioxidant enzyme: PMID 11171786 (2001) and review in PMID 16601572 (2006) --CopperKettle 14:18, 1 June 2009 (UTC)

this article is total crap

This article fails to point out that anti-oxidants are created by microbiology for the purpose of microbiology.. and these systems would be particulary distant and unaffected by the consumption of food and beverage that its pointless to consider "eating" anti-oxidants... except if they are there to stop the apple turning brown.

the term 'anti-oxidant' is so poorly defined, and there is so many nonsensical claims about anti-oxidants and "oxidative stress".. I suspect that failing to include a strong definition leads this article to dance a dance of "consensus" and not address the subject at hand with any solid fact. The solid fact is that "anti-oxidant" is a notional property of a substance in microbiology and is not proved to be a topic relevant to nutrition... See an antioxidant may keep dying cells of apples from turning brown, but so far they escape observation of having any affect on healthy cells...leading one to believe that healthy cells need no outside meddling for optimal life.

I'd recommend PMID 8660387 and PMID 9129943 as good general references on the science, and possibly PMID 15153272 as a recent review on the importance of antioxidants in human health. Tim Vickers (talk) 17:17, 28 January 2010 (UTC)

I share the frustration of 202.92.40.8 (Unfortunately, TimVickers seems to have replied before the bot could sign the strongly negative contribution of 202.92.40.8). The article appears to be validating the widespread health claims about eating "antioxidants". In part this appearance is magnified by mentioning vitamins (A, C, E) which a human can, by definition, only obtain through the diet. Although these substances may have some antioxidant activity, this activity is slight at at the levels which prevent the deficiency diseases. The important effects of these substances are their vitamin activities. (In the case of vitamin C, or ascorbic acid, the ascorbic effect results from its ability to oxidize certain molecules, and not from its ability to prevent oxidation. Trying to understand the importance of vitamin C to human nutrition by calling it an antioxidant therefore is not just silly, it is counterproductive). Many of the important antioxidants (not reducing agents) are produced in the human body, and can use the standard reducing agents — food energy molecules like sugar and fat — without needing any special dietary antioxidants. Many other highly-touted antioxidants, such as the polyphenols (tannins), tend to react with protein (that's how they tan skin into leather) in the digestive system and be eliminated through the colon, making them unavailable through the diet.     Jay L09 (talk) 16:00, 27 May 2010 (UTC)

Although it would not be necessary in the best of all possible worlds, I think that this article could be improved by clarifying the difference between the importance of a chemical in vivo, and the utility of consuming it in the diet.     Jay L09 (talk) 16:00, 27 May 2010 (UTC)

Antioxidants Explained Easy

An easy way to explain antioxidants and free radicals is think of a 5 lane highway. Each lane has cars traveling smoothly with no traffic. The highway represents your body or major organ. The cars represent cells in your body. A crack develops in lane #1. The car in lane #1 hits the crack, spins out of control and runs into the car in lane #2. The car in lane #2 then collides in the car in lane #3 and so on. Soon all the cars are colliding into each other causing all sorts of issues. The crack represents a free radical and the best way to get rid of the crack on the lane is to repair it or fill it in. An antioxidant is the molecule which would fill in the crack, allowing the cars/cells in lane #1 to get back to normal which would also allow the other cars/cells in the subsequent lanes be relatively normal again. This is how antioxidants and free radicals work.

The Antioxidant Detective 04:25, 26 May 2010 (UTC) —Preceding unsigned comment added by NeemaF (talk • contribs)

Well, that was certainly and easy and compelling explanation. I am left wondering, however, whether it has anything to do with reality, or is simply a sales pitch for a useless or perhaps dangerous product.     Jay L09 (talk) 14:43, 27 May 2010 (UTC)

I tell ya, this discussion would be a LOT easier to follow if Wikipedia had a bot that went around and just crossed out anything that had weasel words in it. I can tell you this: ALL of this baloney about antioxidants would be gone in a flash. It's ALL so full of "may" and "might" and "indicates that it may be" and "appears to" and all that. Richard8081 (talk) 03:31, 29 May 2012 (UTC)

Uric Acid

I, for one, find myself unconvinced of the importance of uric acid as an antioxidant. (Perhaps I need to be educated. Oh! Perhaps that's why I read the Wikipedia article.) When I read the uric acid section, there was only one reference, a 40-year-old letter to the editor, with a question as its title. I found the source of the claim about the relative importance of uric acid antioxidant activity in the blood, and was also not completely convinced. Would someone who is more expert in biochemistry than I am address these two points:

• Uric Acid Substituting for Ascorbic Acid in Humans: Is there more recent information than Peter Proctor's 40-year-old letter to the editor, either yea or nay? ("Similar Functions of Uric Acid and Ascorbate in Man?" Nature 228 (1970)868

• Relative Importance of Uric Acid as an Antioxidant in Human Blood Serum: The "more than half" value derives from a paper by S. R. J. Maxwell et al. ("Antioxidant status in patients with uncomplicated insulin-dependent and non-insulin-dependent diabetes mellitus" European Journal of Clinical Investigation (1997)27, 484-490) about a study of diabetic and normal persons. Assays of in vitro blood serum antioxidant activity were linearly regressed against the concentrations of several antioxidants. The correlation coefficients were multiplied by the concentrations, and the results expressed as percentages, normalized to 100%. Uric acid came up as 65.1% Although this is the most obvious method, I question whether it is valid. Thoughts from an expert?

Jay L09 (talk) 06:20, 17 June 2010 (UTC)

This is a very interesting question, thanks for bringing it up! The best review of the literature I found is in the introduction of PMID 8325534, although this is a rather old paper. It cites several papers to support their statement "It has been estimated that urate comprises 30-65% of the peroxyl radical-scavenging capacity of blood plasma." including this Ames paper. The interaction with ascorbate is reviewed in this 1991 paper I think it is well-established that urate can act as an antioxidant, although there is recent controversy surrounding its possible role as a pro-oxidant in stroke, reviewed in PMID 18617849. Tim Vickers (talk) 16:51, 17 June 2010 (UTC)

I've had a go at reworking this section. Tim Vickers (talk) 16:59, 17 June 2010 (UTC)

is it damaged by heat —Preceding unsigned comment added by 123.200.11.6 (talk) 06:43, 28 November 2010 (UTC)

I don't understand this concept.

The first sentence in this article is "An antioxidant is a molecule that inhibits the oxidation of other molecules.". As far as I know, our metablolism relies on the oxidating potential from oxygen in the air. If antioxidants prevented oxygen from oxidating glucose molecules they would be highly toxic. Fortnately it doesn't really seem like antioxidants inhibit the oxidation of glucose molecules. Rather it seems like these antioxidants capture radicals. Shouldn't your definition of an antioxidant rather be "a molecule that captures radicals"?

An oxidizing agent is defined as a molecule that captures electrons from other molecules. Radicals aren't neccessarily oxidazing agents, but from reading this article I get the impression that "free radicals" are oxidizing agents. 152.94.59.5 (talk) 16:10, 7 April 2013 (UTC)