[Neuroscience] Re: Carotenoid Transport into the RPE

John H. via neur-sci%40net.bio.net (by j_hasenkam from yahoo.com.au)
Thu Dec 6 22:44:11 EST 2007


On Dec 7, 4:21 am, Don W <dwil... from prodigy.net> wrote:
> John,
>
>   If you have some time left over, you may want to look at the level
> of zinc recommended for macular degeneration.  The AREDS2 (very large)
> study set the level at 80mg.  But a recent (very small) study says
> they have found zinc as a constituent of drusen.  Now everyone is
> backing off of the 80mg.  The power of a very small study.
>
> Don W.

Thanks Don,

The Blue Mountains study(large) found an RR for high zinc of .56 from
top to lowest quintile, hence a strong protective effect. Damn. Yes,
have been looking at the AREDS studies.

A2E is and R-PE compounds are big constitutents of drusen and
lipofuscin, a retinol binding protein inhibitor 9(4HPR but very toxic)
markedly reduced lipofuscin aggregation, and biochemistry of A2E and
retinoid related proteins indicate that when oxidised, as these easily
are in the retina, do become cytotoxic. So the evidence for reducing
pro-vit A's is quite strong across a number of levels. Yet almost
invariably people are told to eat lots of vit a rich food, even though
there are now a number of studies suggesting that chronic high intake
of the same can have a number of risks including mac degen, liver
damage, osteoporosis and even a hint of increased cancer risk. Now to
zinc:

There is the suggestion zinc is required for carotenoid transport into
the retina.
Zinc is an important component of Cu\Zn SOD, a critical cytoplasmic
endogenous antioxidant.
some say high zinc precludes Cu intake.
But high Cu intake can make you psychotic and in Wilson's Disease,
where cu cannot be eliminated, there is a noticeable ring in the outer
iris arising from Cu accumulation.
At high levels both zn and cu are dangerous, this is true of all heavy
metals.

Some balancing act eh? In a way same problem as pro vit A carotenoids,
a matter of balance but how to determine the right balance for each
person.

Is the zinc issue one of guilt by association? Has anyone tried
chelation therapies for reductions in oxidation in the retina?(strong
odds this would work for Fe, which is present in damaged neurons and
retina) Do we need to contrast high zn and low carotenoid vs low zn
and high carotenoid?

PS: One of the more promising aspects I have come across is strong
evidence that these aggregations can be reduced(note: not rate of
accumulation but actual real reductions in total drusen) by
mitochondrial function enhancement(using what is essentially a "folk
wisdom" approach), bright light avoidance, and keeping away from UV
light and blue light. There's a rub, wear the sunnies to protect the
eyes but keep up the vit D production via UV(much better than pills,
most of which are useless re vit D uptake), and vitamin D has strong
anti cancer properties and anti-inflammatory properties. Ah ya just
can't bloody win, one way or the other the universe is gonna do us
in .... .


Me go mad now, time to come up with my own Theory of Everything and
annoy you lot endlessly until they take me away hey hey ... .

John.


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