过量摄入铜元素易引发老年痴呆

A lifetime of too much copper¹ in our diets may be contributing to Alzheimer's disease, US scientists say. ,
,一生的饮食中摄入过多铜元素可能引发阿尔茨海默症
。, ,However, research is divided, with other studies suggesting copper may actually protect the brain. , ,The latest study in Proceedings ² 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 coming through copper pipes, red meat and shellfish as well as fruit and vegetables are all sources of dietary copper., ,Barrier, ,The study on mice, by a team at the University of Rochester in New York, suggested that copper interfered ³ 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 ⁴ 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 call beta amyloid., ,One of the hallmarks of Alzheimer's disease is the formation of plaques⁵（斑块，瓷片） of amyloid（淀粉体） in the dying brain. , ,Lead researcher Dr Rashid Deane said: "It is clear that, over time, copper's cumulative ⁶ effect is to impair ⁷ 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（晦气 ，剧烈的打击） of increased production and decreased clearance ⁸ of amyloid protein. , ,"Copper is a very essential metal ion and you don't want a deficiency and many nutritious ⁹ foods also contain copper.", ,However, he said taking supplements may be "going overboard a bit".