In the early part of this century, specific factors necessary for growth and survival were beginning to be identified. Frederick Gowland Hopkins, Professor of Biochemistry at Cambridge in England, for example, during the period 1906-1912 found that a growth stimulating principle from milk was present in an alcoholic extract of milk rather than in the ash.
During the same period, W. Stepp in Germany identified one of these “minimal quantitative factors” as a lipid. He found that white mice do not survive in a diet form which all fat been removed by extraction with alcohol/ether.
Soon thereafter, E. V. McCollum and Marquerite Davis in Wisconsin showed that butter or egg yolk, but not lard, contained a lipid soluble factor necessary for the growth of rats. They demonstrated there was present in butter fat a substance that prevented xerophthalmia and was also required for growth.
In 1913 they termed this ‘a lipid-soluble growth factor’. McCollum later named this factor ‘fat-soluble A’, and thereby attributed for the first time the growth stimulating property of these extracts to a single compound. A name changed to ‘vitamin A’ in 1920 by British biochemist Jack Cecil Drummond.
McCollum’s findings were immediately pursued at Yale University by two of the leading American nutritionalists, Thomas Osborne and Lafayette Mendel.
They noticed that in animal fed on a diet deficient in the fat soluble factor, a characteristic eye disease occurred. They found that cod liver oil or butter was an essential growth-promoting food for rats. The year 1913, therefore, was the beginning of the modern age of vitamin A exploration.
In 1932 an English physician successfully treated chicken ill with measles with vitamin A.
Discovery of vitamin A
