Posted by Larry Hoover on November 6, 2004, at 13:45:28
In reply to Re: vitamin E and depression, posted by mistermindmasta on November 6, 2004, at 12:54:13
> Ok, I guess I phrased my original statements a little off from what I actually meant.
You've got a tough audience here, dude. ;-)
> What we see in this study is that people are getting enough vitamin E in their diets, but that this dietary intake is not related to plasma alpha tocopheral. What I wondered when I read this article was, what is causing this metabolic loss of vitamin E? I suggested that although these people are getting enough vitamin E, they might have a higher metabolic requirement for vitamin E due to a "poor diet"... in other words, a diet that leads to a high requirement of antioxidants. A diet that is 100% raw foods would put less demand on the body's antioxidant reserves than a diet that is high in fried foods, would you agree?
I guess I don't see it in quite so dramatic a contrast. Depressives might go for processed or convenience foods more, sure. But e.g. hydrogenation of unsaturated fats reduces oxidative load.
> So in people who eat a diet high in fried foods, their plasma vitamin E might be lower due to increased metabolic demand even though they are getting the RDA. There is no way I can make this conclusion from this study, since it wasn't addressed directly, I am only throwing some personal thoughts out there as to why they have low plasma alpha tocopheral despite adequate oral intake.
Occam's razor would still be useful. I would assume similar diet, rather than an uncontrolled variable, as an a priori analytical perspective.
> I don't know if there's been any study done on this, but I think that depressed people often eat diets that lead to a larger metabolic requirement of nutrients than other populations. Eating a refined, highly processed diet theoretically would lead to a higher requirement of nutrients such as magnesium, chromium, B vitamins, etc... I would assume that vitamine E should be included in that list.
As the antioxidants work in interactive ways, I do agree. Vitamin E might well be a marker compound for a more generalized oxidative burden.
> Or... as you suggest, maybe there are other factors leading to increased oxidative stress rather than a "poor diet". People with depression often have a dysfunction of the cortical frontal lobes, and researchers think this might be because of excess glutamatergic activity causing neurotoxicity.
Right, and that neurotoxicity often expresses itself as degradation of mitochondrial membranes, which then exposes the cytoplasm to free radical stress, which can go on to apoptosis. I think that all neuronal stress is ultimately oxidative stress.
> I can't think of exactly how vitamin E might be neuroprotective in this case, so that neurotoxicity decreases, but maybe it is possible... what do you think?
There is an oxidative/reductive couple between alphalipoic (thioctic) acid and vitamin E. Both serve to stabilize the mitochondrial membrane, which is itself substantially responsible for protecting the cell from the wicked chemistry taking place inside the mitochondrion. You want the ATP to emerge from the mitochondrion, but not e.g. the superoxide.
> Might eating a diet higher than the RDA lead to a lower quantity of neurotoxic events?
I can't see it in any other light.
The RDA is defined in terms of deficiency states in normal healthy people. (Whoever they are, I haven't a clue.) There is no consideration for illness or acute or chronic stressors/perturbations. Nor is there any thought given to optimal intake.
For a visual, see:
http://books.nap.edu/books/0309071836/html/24.html#pagetop
Again, even in the context of that graph, it pertains to normal healthy people. Note that Estimated Average Requirement (EAR) is the 50th percentile of overt deficiency, and although not shown, Adequate Intake (AI) is 77% of the RDA. RDA is two standard deviations above EAR. AI is one standard deviation above.
Methinks optimal may lie further towards the Upper Limit of intake.
Lar
poster:Larry Hoover
thread:412398
URL: http://www.dr-bob.org/babble/alter/20041022/msgs/412586.html