US scientists have reported new evidence that copper can lead to the plaque build-up in the brain that causes Alzheimer's disease, fuelling fresh debate over the mineral's role in dementia.
The scientific community is divided on the question of whether copper - found in red meat, vegetables, dairy products as well as pipes that carry drinking water in much of the developed world - causes or prevents Alzheimer's disease.
For the latest study published on Monday in the Proceedings of the National Academy of Sciences, researchers looked at how copper in the capillaries may cause a breakdown in the blood-brain barrier, leading to a build-up of the protein amyloid beta or the plaques that are a hallmark of Alzheimer's.
According to lead author Rashid Deane, a research professor at the University of Rochester Medical Centre, experiments using mice and human cells showed that low levels of copper delivered via drinking water accumulated in the capillary walls that feed blood to the brain.
"These are very low levels of copper, equivalent to what people would consume in a normal diet," said Deane.
Researchers described their findings in a press release as a "one-two punch" that "provides strong evidence that copper is a key player in Alzheimer's disease".
Other experts who have studied copper and Alzheimer's questioned the findings.