Niacin
Properties
| State | Solid (white crystalline powder) |
| Color | White |
| Solubility | Soluble in water (18 g/L at 25°C); soluble in boiling water and ethanol |
| Melting Point | 236-239°C |
| Boiling Point | Sublimes |
About Niacin
Niacin is a pyridine ring with a carboxylic acid hanging off the 3-position, and that simple structure (formula C6H5NO2, molar mass 123.110 g/mol) is the precursor your body converts into NAD+ and NADP+ — the redox cofactors that move hydride ions through more than 400 enzymatic reactions, including glycolysis, the citric acid cycle, fatty acid synthesis, and the entire electron transport chain. Without niacin, ATP production stops. The historical evidence for that dependence is brutal: pellagra, the deficiency disease, killed an estimated 100,000 people in the early-20th-century American South before Joseph Goldberger traced it to corn-based diets that lacked bioavailable niacin. Mexican cuisine sidestepped the problem centuries earlier through nixtamalization — soaking corn in lime water releases bound niacytin into a form the gut can absorb. Pharmacologically, doses of 1–3 g/day lower LDL and triglycerides while raising HDL, but the prostaglandin-mediated flushing (and risk of hepatotoxicity with sustained-release formulations) keeps niacin from being a first-line lipid drug. The body can also make a small amount of niacin from tryptophan at a roughly 60:1 ratio.
Where you'll encounter it
If you've ever read a cereal box and seen 'niacin' in the fortification list, that's regulatory pellagra-prevention dating back to the 1940s, when the U.S. mandated enrichment of refined flour to eliminate the disease. In a teaching biochem lab, you'll meet niacin as the source of the nicotinamide ring you watch flip between NAD+ and NADH in a UV-Vis assay — the absorbance at 340 nm is one of the first quantitative readouts most students ever generate. Clinically, if you've taken a high-dose niacin tablet for cholesterol, the warm prickling rush across your face and chest twenty minutes later is real GPR109A receptor activation triggering prostaglandin D2 release, and pretreating with 325 mg of aspirin genuinely blunts it.
Common Uses
- Precursor for NAD+/NADP+ cofactors driving over 400 oxidoreductase reactions in cells
- Mandatory fortification additive in U.S. enriched flour and breakfast cereals since the 1940s
- Pellagra prevention and treatment in malnourished and alcohol-dependent populations
- Pharmacological lipid-modifying agent at 1-3 g/day doses for LDL and triglyceride reduction
- Substrate for the NAD+/NADH absorbance assay at 340 nm in undergraduate biochemistry labs
- Tryptophan-niacin conversion teaching example for amino acid metabolism coursework
- Skin flush diagnostic for GPR109A receptor function in clinical pharmacology research
Safety Information
GHS classification: Not classified as hazardous at dietary concentrations; FDA GRAS status. At pharmacological doses (1-3 g/day), niacin causes vasodilatory flushing, pruritus, and headaches in most users; sustained-release formulations carry an FDA black box warning for hepatotoxicity, with case reports of acute liver failure. No formal OSHA PEL exists for niacin powder, but ACGIH recommends standard nuisance dust limits of 10 mg/m3 total dust. Industrial handling requires dust masks and eye protection. Pharmacological niacin therapy requires baseline and periodic liver function testing (ALT, AST). Aspirin 325 mg taken 30 minutes before each dose blunts flushing.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.