The European food safety authority (EFSA) last evaluated vitamins and minerals for safety in 2006 and set a so-called Tolerable Upper Intake Level (UL) for each micronutrient, provided sufficient data were available. This UL reflects the maximum safe level of a micronutrient that will not cause adverse effects when taken daily from all sources for a lifetime.
| The maximum safe daily intake for copper is 5 mg. The maximum safe daily intake for copper is 5 times the EU recommended daily intake (Nutrient Reference Value, NRV). |
The above safe maximum daily intake applies to adult men and women 18 years of age and older. Due to insufficient data, the safe daily intake limit for copper does not apply to pregnant and lactating women.
Estimates of copper intake in the Federal Republic of Germany indicate that the safe maximum daily intake for copper is not reached. Although the upper intake of copper in the German population is close to the safe daily intake, EFSA does not consider this to be an increased risk. The healthy human body has effective mechanisms to respond to excessive copper intake, with reduced intestinal absorption and increased urinary excretion.
Intake of 10 mg of copper per day in the form of supplements in addition to the conventional diet, taken for 12 weeks, did not result in any adverse effects. Another study also observed no adverse effects at levels of 6 mg of copper per day.
The NOAEL (No Observed Adverse Effect Level) – the highest dose of a substance that has no detectable and measurable adverse effects even with continued intake – is 10 mg of copper, which is twice the safe maximum daily intake.
Adverse effects of excessive copper intake are acutely mainly gastrointestinal disturbances and long-term damage to the liver.
Acute symptoms of copper poisoning occur at higher levels and include symptoms such as stomach pain, nausea (nausea), vomiting, and even watery, bloody diarrhea (diarrhea). Gastrointestinal disturbances such as diarrhea (diarrhea) and vomiting have been observed following excessive copper intake in amounts ranging from 15 to 75 mg of copper per day. In other studies, symptoms such as stomach burning and vomiting occurred at doses as low as 10 to 15 mg of copper per day. These side effects subsided after the copper intake was stopped.
Drinking water containing copper from copper-containing pipes or vessels caused gastrointestinal disturbances already in amounts of 2 to 32 mg. Therefore, a lower NOAEL (No Observed Adverse Effect Level) – the highest dose of a substance that has no detectable and measurable adverse effects even with continued ingestion – of 4 mg of copper per liter was established for copper intake from drinking water.
The lethal dose of copper salts is given by the WHO (World Health Organization) as 200 mg per kg body weight per day. This results in severe symptoms such as bloody diarrhea and urine, hypotension (low blood pressure), liver necrosis (life-threatening cell death of the liver), renal and circulatory failure, and even coma and death.
In a single case report, long-term use of an amount of 30 mg of copper per day, taken for 2 years, followed by use of 60 mg of copper per day for an indefinite period of time, resulted in acute liver failure.
In patients with Wilson’s disease (synonyms: Hepatolenticular Degeneration, Hepatocerebral Degeneration, Copper Storage Disease, Wilson’s Disease, Pseudosclerosis Westphal; autosomal recessive inherited disease in which copper metabolism in the liver is disturbed by one or more gene mutations), even copper intake in normal amounts leads to an accumulation of copper in the body and thus to undesirable effects on the liver, central nervous system, eyes as well as the kidney at an early stage. Wilson’s disease is therefore treated with medication.
