The pellagra epidemic of the early 20th century may have been the deadliest epidemic of a specific nutrient deficiency in U.S. history. Part one covers what it is, its appearance in 19th-century Italy, and the first reports of it in the U.S.
Research:

James Braid, Surgeon and Father of Hypnotism
43:36

Gladys Bentley
40:09

SYMHC Classics: Moms Mabley
33:10