Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. Niacin is obtained in the diet from a variety of whole and processed foods, with highest contents in fortified packaged foods, meat, poultry, red fish such as tuna and salmon, lesser amounts in nuts, legumes and seeds. Niacin as a dietary supplement is used to treat pellagra, a disease caused by niacin deficiency. Signs and symptoms of pellagra include skin and mouth lesions, anemia, headaches, and tiredness. Many countries require its addition to wheat flour or other food grains, thereby reducing the risk of pellagra.