A lifetime of too much copper in our diets may be contributing to Alzheimer's disease, scientists say.
However, research is divided, with other studies suggesting copper may actually protect the brain.
The latest study in Proceedings of the National Academy of Sciences showed high levels of copper left the brain struggling to get rid of a protein thought to cause the dementia.
Copper is a vital part of our diet and necessary for a healthy body. Tap water via copper pipes, red meat and shellfish, as well as fruit and vegetables are all sources of dietary copper.
The study on mice, by a team at the University of Rochester in New York, suggested that copper interfered with the brain's shielding - the blood brain barrier. Mice that were fed more copper in their water had a greater build-up of the metal in the blood vessels in the brain.
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.
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