Niacin, also known as vitamin B3, is an essential nutrient that helps the body convert food into energy. It plays a crucial role in maintaining healthy skin, nerves, and digestion. Niacin can be found in various foods, including meat, fish, eggs, and green vegetables, as well as in fortified cereals. In addition to its dietary sources, niacin is also available as a dietary supplement. It is sometimes used to help manage cholesterol levels and improve heart health. However, excessive intake can lead to side effects, so it's important to consult a healthcare professional before starting any supplementation.