Niacin is quickly and easily absorbed from the intestinal tract and distributed extensively to body tissue after being hepatically metabolized. It is converted by the body to its active coenzyme forms, nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate.
NAD and NADP where their oxidized forms, that is, NAD+ and NADP+ play an essential role in many biochemical reactions. The two coenzymes are required for oxidative reactions crucial for energy production, but they are also substrates for enzymes involved in non-redox signaling pathways, thus regulating biological functions, including gene expression, cell cycle progression, DNA repair and cell death.
Niacin is a B vitamin that's made and used by human body to turn food into energy. It is required for cell respiration and helps in the release of energy and metabolism of carbohydrates, fats and proteins, proper circulation, maintenance of healthy skin, functioning of the nervous system and normal secretion of bile and stomach fluids.
Niacin also helps the body make sex- and stress-related hormones and improves circulation and cholesterol levels.
Clinical evidence of niacin deficiency includes fatigue, poor appetite, diarrhea, irritability, headache, emotional instability and possible memory loss. These may lead to changes in the skin, mucosa of the mouth, stomach and intestinal tract and the nervous system.
Niacin: An essential human nutrient
