Nicotinic acid, also known as niacin or vitamin B3, is a water-soluble vitamin essential for human health. It plays a crucial role in converting food into energy and is involved in the synthesis of fatty acids and cholesterol. Nicotinic acid can be found in various foods, including meat, fish, eggs, and green vegetables. In addition to its dietary importance, nicotinic acid is used in medicine to help manage cholesterol levels and improve cardiovascular health. It can also support skin health and aid in the functioning of the nervous system. However, excessive intake may lead to side effects, such as skin flushing or gastrointestinal issues.