New research finds that
copper in amounts readily found in our drinking water, the foods we eat
and the vitamin supplements we take likely plays a key role in
initiating and fueling the abnormal protein build-up and brain
While the mineral is
important to healthy nerve conduction, hormone secretion and the growth
of bones and connective tissue, a team of researchers from the
University of
Rochester Medical Center suggested that too much of it may be a bad thing, and they set about to explore copper's dark side.
What they found, said neuroscientist Rashid Deane, is "pretty scary":
A steady diet of copper, even at entirely allowable levels, breaks down
the barrier that keeps unwanted toxins from entering the brain, and
that it fuels an increase in production of beta-amyloid but impedes the
performance of proteins that clear the stuff from the brain.
On top of that, Deane's team
found that copper accumulation in the brain causes inflammation in brain
tissues. At low levels and for short durations, that may be a good sign
that brain tissues are responding to the danger of excess beta-amyloid
proteins and are trying to expel them, Deane said. In time, however,
neuro-inflammation can overwhelm the brain and begin to damage cells, he
added.
Copper
is found in a wide range of the foods we eat, including red meat,
shellfish, nuts and many fruits and vegetables, as well as in many
vitamin supplements. It also leaches from copper pipes into the water we
drink. While we take in copper from foods, it is most readily absorbed
into the bloodstream in its "free" form, say researchers -- when it is
suspended in water.
The research, which lay out the case against a long-suspected culprit
in Alzheimer's disease, is published Monday in the journal PNAS.
Deane said that, in the absence of effective treatments for
Alzheimer's disease, his team's findings suggest a way to prevent the
memory-robbing disorder or slow it once it has taken hold. One drug
candidate currently in Phase 2 trials -- an agent that binds with copper
molecules and escorts them out of the body -- might well do that, said
the study's lead author. But even now, Deane said, consumers could be
checking their vitamin supplements for copper and researching whether
their water filters are equipped to remove copper from their drinking
supply.
"The key will be striking the right balance between too much and too
little copper consumption," Deane said. "Right now, we cannot say what
the right level will be. But diet may one day play an important role in
regulating this process."
Deane's team worked with mice and with human brain cells that play a
key role in forming the blood-brain barrier to detect the mechanisms by
which copper might start, drive or worsen Alzheimer's disease. They
noted that in the elderly, the blood-brain barrier becomes "leaky,"
letting in larger toxic molecules circulating the blood. So too does the
concentration of copper in the brain's small blood vessels increase
with age.
Starting in the mouse-equivalent of young adulthood, they fed mice a
regular diet, but gave half of them water that contained levels of
copper equal to one-tenth the maximum allowed by the
Environmental Protection Agency.
The other half were given double-distilled water with a very low copper
content -- less than 2% of that given to the high-copper group. In a
second experiment, older mice bred for their propensity to develop
beta-amyloid plaques were fed the copper-tainted water or the low-copper
water.
After three months, the effects were dramatic: In the mice who took
in high doses of copper, the scientists observed that copper accumulated
in the small blood vessels of the brain. Compared to mice on low doses
of copper, the high-copper mice showed four times fewer levels of a
protein called LRP1, which transports beta-amyloid and other debris out
of the brain. They also showed abnormally high levels of beta-amyloid
production and of neuro-inflammation.
As they aged, the brains of mice who were fed high doses of copper
had beta-amyloid levels on par with those of mice who drank low-copper
water but had been bred to develop beta-amyloid at high rates.
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