A nutrient in the vitamin B complex that the body needs in small amounts to function and stay healthy. Nicotinic acid helps some enzymes work properly and helps skin, nerves, and the digestive tract stay healthy. Nicotinic acid is found in many plant and animal products. It is water-soluble (can dissolve in water) and must be taken in every day. Not enough nicotinic acid can cause a disease called pellagra (a condition marked by skin, nerve, and digestive disorders). A form of nicotinic acid is being studied in the prevention of skin and other types of cancer. Nicotinic acid may help to lower blood cholesterol. Also called niacin and vitamin B3.