Lutein as a model dihydroxycarotenoid for the study of pigmentation in chickens.

A model for the study of pigmentation in young chickens is described in which a white corn-soy based diet supplemented with varying amounts of free lutein (0, 5, 10, 20, 40, and 80 micrograms/g diet) was fed from hatching until 3 weeks of age. The carotenoid content of tissues dissected from chicks of the various groups was measured by high pressure liquid chromatography. In intestinal contents, three forms of lutein were found, with lutein monoester greater than free lutein greater than lutein diester. In the serum, free lutein (96%) and lutein monoester (4%) were found. In the liver, free lutein (80%), monoester (20%), and traces of diester were found. In the integument (toe web), diester greater than monoester approximately equal to free alcohol were found. In each tissue, the concentrations were directly proportional to the dietary concentration of free lutein. The simplest explanation of the data appears to be that part of the free lutein in the diet is esterified during its passage down the intestinal tract and, regardless of its status when absorbed, it is transported in the body as the free alcohol. When it enters depot sites such as the integument, lutein is deposited mainly as esters, presumably as the result of local enzymatic activity.