Even, Accurate Cooking. Because of its excellent conductivity (which is up to twenty times more powerful than that of stainless steel), copper cookware allows heat to spread evenly and accurately, enabling food to cook uniformly and at easily regulated temperatures. Using an uncoated or unlined copper pan can release copper salts into food. Copper toxins could cause adverse effects on the body, such as vomiting, diarrhea or nausea. Ingesting large quantities of copper could also result in liver, kidney and stomach issues.