B3, also known as niacin, is a water-soluble vitamin that plays a crucial role in converting food into energy. It is part of the B-vitamin complex and is essential for the proper functioning of the nervous system, digestive system, and skin health. Niacin can be found in various foods, including meat, fish, eggs, and green vegetables. In addition to its dietary sources, niacin can also be synthesized in the body from the amino acid tryptophan. It is important for maintaining healthy cholesterol levels and may help reduce the risk of heart disease. A deficiency in niacin can lead to a condition known as pellagra, characterized by symptoms like dermatitis, diarrhea, and dementia.