Vitamin B3 (Niacin)

Vitamin B3, also known as niacin, is an essential water-soluble vitamin. It plays a crucial role in numerous metabolic processes, including converting food into energy, supporting cellular function, and maintaining DNA integrity. Niacin exists in several forms, primarily nicotinic acid and nicotinamide (also called niacinamide). Both forms can be obtained through diet or supplements and serve as precursors for essential coenzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes are vital for over 400 enzymatic reactions in the body, participating in energy metabolism, antioxidant defense, and cell signaling (NIH ODS, PubChem). Historically, niacin deficiency, known as pellagra, was a significant public health problem characterized by dermatitis, diarrhea, and dementia. While rare in developed countries today due to fortified foods, understanding its role is still important. Niacin's pharmacological effects, particularly with nicotinic acid at higher doses, extend beyond preventing deficiency and have been studied for their impact on lipid profiles and cardiovascular health (Mayo Clinic, MedlinePlus). The body can synthesize some niacin from the amino acid tryptophan, though this process is not efficient enough to meet daily requirements without dietary intake. Good dietary sources of niacin include meat, poultry, fish, nuts, legumes, and fortified cereals. Nicotinic acid and nicotinamide are commonly found in dietary supplements. Notably, nicotinic acid and nicotinamide have distinct physiological effects, especially at higher doses, with nicotinic acid being more commonly associated with lipid-modifying properties and specific side effects like the "niacin flush" (NIH ODS, DrugBank).