Any comments? Is this really true? I am about to order a new stock of antioxidants, but should I skip it and live "normal" instead?
No, it's not true. It's equivocation. It's not telling the whole story. And it's deliberately biased and I don't believe the author believes it entirely either. And simply stating flat out that antioxidants are a "myth" is a downright falsehood. There are a very long list of published studies documenting the positive in vivo effects of various supplements that are generically referred to as "antioxidants." Often times, many of these supplements have a number of positive effects in animals that aren't even directly attributable to their antioxidant action. There are very long lists of in vivo studies on a variety of different antioxidant nutritional supplements proving benefit in animals in both healthy and diseased states.
I would like to point out that as far as human studies are concerned, historically scientists seem to have been fixated on about three substances: d or d/l alpha tocopherol, Vitamin C, and beta carotene. Recently, green tea seems to be making some progress as far as getting attention, and it routinely shows more broad spectrum benefit than the first three in human studies . There seems to be this "myth" that an antioxidant is an antioxidant, and that results from any one of these three substances would be representitive of all antioxidants. I actually consider these first three substances to be of fairly low priority relatively speaking (particularly as antioxidants), even though I supplement with all three. It's a shame that historically so many other substances that have shown so much benefit in animals have not been extended to human trials. This is not to mention that alpha tocopherol should not be used in isolation in high dosages. It's been shown to be rather pro-oxidant in high dosages when not administered along with gamma tocopherol and other E vitamers. Much of the exogenous gamma tocoperhol is actively metabolized and excreted not long after ingestion, and the ways in which it improves health and such are not fully understood, and yet the evidence shows that it's important to be taken along with alpha tocopherol. It's known that alpha tocopherol taken in isolation lowers levels of gamma tocopherol in the blood, and this may be the reason for some of the negative studies. Another reason is that sometimes the synthetic racemate, d/l alpha tocopherol is used. The artificial L enantiomer has been linked to health problems and should be eliminated. With regard to Vitamin C, it's bioavailability is fairly poor as a water soluble molecule, and its antioxidant action is better for extracellular purposes and preventing oxidation of cholesterol. It still is obviously an important antioxidant, though. It also has benefits for the immune system, increases collagen synthesis in high dosages, etc.
I should note, however, that only a smaller percentage of the in vivo animal studies are done in healthy animals and humans. Most of these studies are done in animals in diseased states. It certainly would be helpful if a larger percentage of the work being done to study natural substances would evaluate their effects in healthy animals. With that said, there are still plenty of studies done in healthy animals (including lifespan studies for some substances) which show that supplements considered to be antioxidants improve various parameters of health or even extend lifespan in healthy animals.
If you want to start reading the results of studies like these, I recommend you subscribe to the "sci.life-extension" newsgroup at groups.google.com, or through your local news server. There are some people there who are very good at finding positive in vivo studies on these substances (and the negative, which comprise a small percentage), and the study abstracts are posted to this group as they become available.
I would put forth the general idea that supplements should not be regarded as substitutes for a healthy lifestyle. A healthy lifestyle begins with your whole daily routine: your regular sleeping habits, exercise, diet and calories, and choice of lifestyle and refraining from harmful habits. These come first. You might think of nutritional supplementation as helping to "augment" rather than subtitute for, a healthy lifestyle that will lead to a long and healthy life.
Antioxidants are neither all good nor all bad. Generally speaking, whenever a conventional antioxidant neutralizes a free radical that would otherwise be taken care of say by, SOD followed by GPX or catalse, it will have been neutralized less efficiently, and net effect may be "slightly" negative. The body's own catalytic antioxidant enzymes in many ways are more efficient at dealing with certain free radicals, and very limited evidence suggests that supplementation with different antioxidants may lower levels of some of these enzymes as part of a feedback mechanism. But on the otherhand, certain supplements also upregulate these enzymes. And many standard antioxidants also help to recycle each other in a network, helping to eliminate any small increase in oxidative stress. So, it's as much about how many you take, and in what dosages and what combinations as it is about any one substance in particular. It's about synergy of antioxidants.
I will say that peroxides have been, relatively speaking, ignored compared to active ROS. Antioxidants taken with effective peroxide neutralizing agents that work in vivo may be important. Unfortunately, there aren't really any natural super peroxide destroyers that I'm aware of. Some have some small but meaningful action against peroxides, but nothing too extensive. We're basically limited at this point to thiodipropionic acid and dilauryl thiodipropionate. And we don't really know if these are effective for in vivo purposes because of the lack of research. Although I have looked at the chronic dosing in rats using these substances, and they appear to be pretty non-toxic in rodents. Unfortunately in chronic toxicity studies the habit is too kill off the animals early (which makes little sense to me), so we don't know how thiodipropionates may affect the aging process, or even know if they are bioavailable to mitochondria.
Recently, mice genetically engineered to overproduce catalase within mitochondria had significantly extended maximum lifespans. And a follow-up study showed that upregulating a peroxide destroyer within the heart mitochondria alone extended lifespan. So, peroxide neutralizing agents are clearly part of the equation and hopefully future research will reveal or produce substances that we can take exogenously for this purpose. In the meantime, we have substances like Glisodin, Bacopa (Protandim), and others that help to upregulate things like GPX and catalase, and thus these substances may form an important part of any antioxidant regimen.
With regard to the free radical theory of aging, MIFRA (the mitochondrial subset of this theory), seems to be taking over, so substances available and particularly active in mitochondria (ALCAR, lipoic acid, etc) are what are most interesting at this point. Unfortunately, CoQ10 has 'mostly' failed to have benefit for aging, but some of the quirky things about CoQ10 and its effects on the respiratory chain shouldn't really leave us feeling surprised. I'm still hoping that R-ALA or R-ALA+ALCAR will be able to extend lifespan in normal rodents.
