Some studies have suggested that zinc may help cure the common cold or at least decrease the duration of a cold. Zinc lozenges are a big seller for this reason. More research needs to be conducted to prove this theory. Zinc is relatively nontoxic in doses up to 45 mg per day. Doses higher than 150 mg can cause diarrhea, abdominal cramps, and vomiting.
High doses can interfere with the body's immune function.
Taking doses higher than the recommended level can also interfere with the absorption of copper, another key mineral. This can cause a copper deficiency. High doses can also reduce iron absorption. Taking more than the recommended amount of zinc from a supplement has no proven benefits and can cause several risks. Eating lean meat regularly will ensure the proper level of zinc intake.