Conrad Arnold Elvehjem (May 27, 1901 – July 27, 1962) was internationally known as an American biochemist in nutrition.
In 1937 he identified two vitamins, nicotinic acid, also known as niacin, and nicotinamide, which were deficient directly in human pellagra, once a major health problem in the United States.
Collectively, nicotinic acid and nicotinamide are termed vitamin B3 and are now understood to be precursors of nicotinamide adenine dinucleotide.