Niacin (Vitamin B3) is a common name for both nicotinic acid and nicotinamide. It is a water soluble vitamin, its derivatves such as NADH are an essential component in energy metabolism in the the living cell. Lack of niacin causes the deficiency disease pellagra
Nicotinic acid reacts with hemoglobin and myoglobin in meat to form a brightly coloured complex, and so has been used as a food additive, typically to improve the colour of minced meat. However, there have been numerous occasions when excess niacin was added to the meat in processing; niacin in large quantities is a vasodilator, and those consuming such meat typically suffer short-lived but unpleasant symptoms such as extremne skin flushing, itching, gastric disturbances, and lowering of blood pressure. Though still licensed as a food colour agent in some countries, it is not licensed as such in Europe.