Are food additives healthy or unhealthy? This is a controversial topic in society today. Many people associate food additives with highly processed convenience foods that are unhealthy. But not all food additives are unhealthy. Iodine, in the form of potassium iodide, was the first additive approved by the federal government for use in foods. Potassium iodide is added to salt to prevent thyroid diseases caused by a lack of iodine in the diet. The presence of iodide in iodized salt can be demonstrated by reaction with chlorine water, a strong oxidizing agent.