Vitamin B3, also called nicotinic acid and niacin, is a water-soluble vitamin necessary for many aspects of health, growth, and reproduction. It is part of the vitamin B complex and is involved in the oxidative release of energy from food, protects the skin, and helps improve circulation. Nicotinic acid is an essential component of a mammalian diet. It is the pellagra-preventing factor of vitamin B. The amide, nicotinamide, is incorporated into nicotinamide adenine dinucleotide.

Niacin is one of the most stable of the B vitamins. It is resistant to the effects of heat, light, air, acid, and alkali. White crystalline substances that are soluble in both water and alcohol, niacin and niacinamide are both readily absorbed from the small intestine. Small amounts may be stored in the liver, but most of the excess is excreted in the urine.

Another important fact about vitamin B3 is that it can be manufactured from the amino acid tryptophan, which is essential (needed in the diet). Niacin is thus not truly essential in the diet when enough protein, containing adequate amounts of tryptophan, and other nutrients are consumed. When niacin is not present in sufficient amounts, extra protein is needed. Also, when we are deficient in such nutrients as vitamins B1, B2, and B6, vitamin C, and iron, we cannot easily convert tryptophan to niacin.

Vitamin B3 is known to aid in promoting a healthy digestive system, be important for the health of the skin, increase circulation and help reduce blood pressure, lower cholesterol and triglycerides, promote relaxation, facilitate orgasms, and act as a mild growth-hormone releaser.