Nature of the “Vitamin A-Like Factor” in Lard

Biological assays on molecular distillates from lard showed that lard contains vitamin A activity equivalent to about four-tenths to two units per gram. Chromatographic fractionation of unsaponifiables from lard and molecular distillates from lard yielded eluates which gave positive Carr-Price tests and typical vitamin A spectral curves, except in fractions having an extremely high ratio of unsaponifiables to units of vitamin A. It is concluded that the biological vitamin A activity of lard is largely attributable to the presence of typical vitamin A. The so-called “sparing” action of lard on utilization of added vitamin A in diets is in all probability due to the presence in lard of hitherto unrecognized typical vitamin A.