In 1913, Elmer McCollum discovered the first vitamins, fat-soluble vitamin A, and water-soluble vitamin B (in 1915; now known to be a complex of several water-soluble vitamins) and named vitamin C as the then-unknown substance preventing scurvy. Lafayette Mendel and Thomas Osborne also performed pioneering work on vitamins A and B. In 1919, Sir Edward Mellanby incorrectly identified rickets as a vitamin A deficiency because he could cure it in dogs with cod liver oil. In 1922, McCollum destroyed the vitamin A in cod liver oil, but found that it still cured rickets. Also in 1922, H.M. Evans and L.S. Bishop discover vitamin E as essential for rat pregnancy, originally calling it "food factor X" until 1925. COUNT 5
QSN1 What was notable about the discovered vitamin A? ANS1 fat-soluble QSN2 Which property was vitamin B found to have? ANS2 water-soluble QSN3 Which disease was vitamin C claimed to help prevent? ANS3 scurvy QSN4 What was cod liver oil able to help cure in dogs? ANS4 rickets QSN5 What was referred to as "food factor X"? ANS5 vitamin E