Vitamin B3 Niacin
About Vitamin B3 Niacin
Niacin, or vitamin B3, refers to nicotinic acid and nicotinamide, both precursors of the coenzymes NAD and NADP. Recommended intakes are expressed as niacin equivalents because the body can also make niacin from the amino acid tryptophan, and they vary by age, sex and life stage. NAD and NADP take part in hundreds of oxidation reduction reactions, and NAD is also used by enzymes involved in DNA repair. Deficiency causes pellagra, classically described by the four Ds: dermatitis on sun exposed skin, diarrhea, dementia and, if untreated, death. Pellagra was epidemic in the American South in the early twentieth century among people living on corn based diets, in which niacin is poorly available without alkali treatment. Joseph Goldberger showed that pellagra was nutritional rather than infectious. At pharmacological doses nicotinic acid lowers LDL cholesterol and triglycerides and raises HDL, but it causes flushing and can cause liver toxicity and raised blood sugar, and large outcome trials have not shown clear cardiovascular benefit when added to statins.
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