Copper Linked To Alzheimer's Disease, BBC, 19 August 2013
"Mice that were fed more copper in their water had a greater build-up of the metal in the blood vessels in the brain.It's important to note that the study in this article, like its predecessors, investigated inorganic or free copper, the kind you find in copper pipes and vitamin pills, not food. Inorganic copper enters the brain more readily than organic copper (the kind you find in food). Also, inorganic copper is more readily absorbed in the intestine and ends up in the bloodstream faster and in greater quantities than organic or food copper which is first transported to the liver and attached to blood chaperons.
The team said this interfered with the way the barrier functioned and made it harder for the brain to get rid of a protein called beta amyloid. ... One of the hallmarks of Alzheimer's disease is the formation of plaques of amyloid in the dying brain.
Lead researcher Dr Rashid Deane said: "It is clear that, over time, copper's cumulative effect is to impair the systems by which amyloid beta is removed from the brain."
He told the BBC that copper also led to more protein being produced: "It's a double whammy of increased production and decreased clearance of amyloid protein.
"Copper is a very essential metal ion and you don't want a deficiency and many nutritious foods also contain copper."
However, he said taking supplements may be "going overboard a bit".
Copper deficiency is rare because it's found in so many foods (beef, lamb, oysters, crabs, mushrooms, beans, nuts, seeds, soy foods, greens (spinach, kale, etc.), potatoes, peppers, asparagus, radishes, tomatoes, squashes, carrots, parsnips, beets, okra, frogs legs...). Taking a supplement "to ensure you're getting enough" copper is pretty much ensuring higher levels in the brain, with a higher risk of plaque formation and dementia.