The level at which copper causes problems is unclear. But in combination with zinc, up to 3 mg per day is considered safe. People drinking tap water from new copper pipes should consult their doctor before supplementing, since they might be getting enough (or even too much) copper from their water. People with Wilson’s disease should never take copper.

Preliminary evidence shows that the levels of copper in the blood were higher among people who died from coronary heart disease than among those who did not.⁹ However, animals studies and some human studies suggest that, if anything, copper may prevent the development of heart disease. Although it is not clear why people who died of heart disease had elevated copper levels, this finding could be due to chronic inflammation, which is known to be associated with increased copper levels.¹⁰