one of provitamins A; alpha particle bombardment with radon effects the conversion of kitol to vitamin A; occurs in variety of fish liver oils & in livers of oxen & sheep; RN given refers to (1alpha,2alpha,5alpha(1E,3E),6beta(1E,3E,5E))-isomer; kitol A & kitol B are geometrically isomeric components of kitol; structure of kitol in first source; structure of kitols A & B in second source