The vitamin that treats pellagra has also turned up inside meteorites
Nicotinamide, one form of vitamin B3, cures the deficiency disease pellagra without the skin flushing its cousin niacin causes. It sits at the heart of the molecule every cell uses to shuttle energy, is sold by the tens of thousands of tonnes, and has even been detected in carbon-rich meteorites from space.
Chemically it is a pyridine ring carrying an amide group, and it was identified between 1935 and 1937. It occurs in yeast, meat, fish, milk, nuts, mushrooms and green vegetables, and some countries add it to grain. The World Health Organization lists it as an essential medicine, and it is sold as a cheap generic and over the counter. Industrial production is large: a bacterial enzyme from Rhodococcus rhodochrous J1 makes 3500 tons a year for animal feed alone, and worldwide sales reached 31,000 tons in 2014, according to Ullmann's Encyclopedia of Industrial Chemistry.
Its real importance is biochemical. Cells build nicotinamide into NAD+ and NADP+, cofactors that drive sugar breakdown, the citric acid cycle and the final energy-harvesting steps in mitochondria. The nicotinamide ring is the working part: accepting a hydride breaks its aromatic stability, storing energy that is later released to help make ATP. Oxidising one mole of NADH yields 158.2 kJ. The body can also make NAD+ from tryptophan and niacin, so dietary nicotinamide is one route among several.
Medically, it is the preferred treatment for pellagra, and as a cream it is used against acne, where it has anti-inflammatory effects and in one regime cut sebum output after two to four weeks. A 2015 trial found fewer new nonmelanoma skin cancers and actinic keratoses in people at high risk. Studies are also exploring whether it can protect retinal ganglion cells in glaucoma, with some improvements in visual fields, though it is not approved for that use.
Side effects are generally slight, and normal amounts are considered safe in pregnancy. High doses are another matter: acute liver injury has been documented in at least one case above 3000mg, and people with liver disease should not use it. Research into other conditions, from psoriasis to blistering autoimmune disorders, remains tentative.
Source: Nicotinamide
