Excessive intake of raw cabbage or nuts can also reduce the uptake of iodine into the thyroid gland and lead to deficiency. Supplements Multivitamin and mineral supplements may provide the RDA of iodine, and it is also is present in kelp-based supplements. Safety Large doses of iodine can be toxic, leading to tachycardia, anxiety, blurred vision and vomiting. Copper Copper plays an important role in the development of red blood cells, and in the pigmentation of hair and skin. In addition, copper is a vital factor for strong bones and is also required for central nervous system activity.
Most unprocessed foods contain some copper.
Soft water may also contain copper, dissolved from copper pipes. Copper deficiency is rare, and people eating normal, unrestricted diets do not need to be concerned about their intake. Safety Excessive levels of copper can be toxic, causing destruction of red blood cells, and liver and kidney damage. High doses of copper also reduce zinc absorption. In Wilson's disease, an inherited disorder, the patient cannot excrete copper and suffers from long-term copper poisoning.