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 zinc is 25 mg. The maximum safe daily intake for zinc is 2.5 times the EU recommended daily intake (Nutrient Reference Value, NRV). |
The above safe maximum daily intake applies to adults 18 years of age and older and to pregnant and lactating women.
Adverse side effects of excessive zinc intake from conventional foods have not been observed.
The data from the NVS II (National Nutrition Survey II, 2008) on the daily intake of zinc indicate that the safe daily maximum amount is not reached via conventional foods. In the form of food supplements, a slight exceedance of the safe daily intake for zinc is possible, but EFSA does not consider this to be an increased risk.
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 – was set by EFSA at 50 mg of zinc, which is twice the safe daily limit.
Adverse effects of excessive zinc intake
Acutely high zinc intake in amounts of 225 to 450 mg resulted in adverse effects such as nausea (sickness), vomiting, abdominal pain (stomach ache), cramps, and diarrhea (diarrhea).
Sustained excessive zinc intake of 150 to 300 mg per day resulted in copper deficiency in studies, with associated symptoms of anemia (anemia), neutropenia (reduction of white blood cells in the blood), and impaired immune response. Amounts of 53 mg of zinc per day, taken for 90 days, remained without undesirable side effects on copper status.
Furthermore, the influence of increased zinc intake on lipid metabolism is discussed. In studies with 160 mg zinc per day, taken for 6 weeks, reduced HDL (high density lipoprotein) concentrations were observed. Another study with 150 mg of zinc per day, taken for 12 weeks, did not observe any effect on lipid metabolism. Overall, study results are inconsistent at intakes between 40 and 160 mg of zinc per day and do not allow a clear conclusion on effects of zinc on lipid metabolism.
