nicotinamide

Nicotinamide, also known as niacinamide, is the amide form of vitamin B3. It is a water-soluble vitamin and one of the two principal forms of vitamin B3, the other being nicotinic acid (niacin). Nicotinamide is a component of the essential coenzymes nicotinamide adenine dinucleotide (NAD+) and NADP+ and participates in numerous cellular redox reactions.

Chemical identity and properties: Nicotinamide is chemically named pyridine-3-carboxamide. Its molecular formula is C6H6N2O and its molecular weight is about 122.12 g/mol. It forms as a white crystalline solid and is soluble in water, making it suitable for dietary and pharmaceutical use.

Biological role: In humans, nicotinamide serves as a precursor in NAD+ biosynthesis via the salvage pathway. NAMPT catalyzes the conversion of nicotinamide to NMN, which is then converted to NAD+ by NMNAT enzymes. NAD+ and NADP+ are essential coenzymes in energy metabolism and various biosynthetic pathways. Nicotinamide can also act as a substrate for NAD+-dependent enzymes such as sirtuins and poly(ADP-ribose) polymerases; at high concentrations, it may inhibit some of these enzymes and affect cellular NAD+ metabolism.

Uses and sources: Nicotinamide is used as a dietary supplement to prevent or treat niacin deficiency and pellagra. It is also employed in fortified foods and is widely used in cosmetics and skincare products for its reported anti-inflammatory and barrier-supporting properties. It is available in various pharmaceutical formulations and as a nutritional supplement.

Safety and regulations: Nicotinamide is generally well tolerated at recommended intakes. Excessive intake can cause adverse effects, including gastrointestinal symptoms and potential liver concerns with prolonged high-dose use. It is recognized as a form of vitamin B3 in many dietary guidelines.