Nutritional manipulation of primate retinas, III: Effects of lutein or zeaxanthin supplementation on adipose tissue and retina of xanthophyll-free monkeys

PURPOSE. Macular pigment ( MP) is composed of the xanthophylls lutein ( L) and zeaxanthin ( Z) and may help to prevent age- related macular degeneration or retard its progression. In this study the effects of L or Z supplementation on carotenoid levels was examined in serum, adipose tissue, and retina in rhesus monkeys with no previous intake of xanthophylls. METHODS. From birth to 7 to 16 years of age, 18 rhesus monkeys were fed semipurified diets containing all essential nutrients but no xanthophylls. Six were supplemented with pure L and 6 with pure Z at 3.9 mu mol/ kg per day for 24 to 101 weeks. At baseline and at 4- to 12- week intervals, carotenoids in adipose tissue were measured by HPLC. At study completion, carotenoids in serum and retina ( central 4 mm, 8- mm annulus, and the periphery) were determined. Results were compared with data from control monkeys fed a standard laboratory diet. RESULTS. Monkeys fed xanthophyll- free diets had no L or Z in serum or tissues. After L or Z supplementation, serum and adipose tissue concentrations significantly increased in the supplemented groups. Both L and 3R, 3 ' S- Z ( RSZ or meso- Z, not present in the diet) were incorporated into retinas of monkeys supplemented with L, with RSZ present only in the macula ( central 4 mm). All- trans Z, but no RSZ, accumulated in retinas of monkeys supplemented with Z. CONCLUSIONS. L is the precursor of RSZ, a major component of macular pigment. Xanthophyll- free monkeys can accumulate retinal xanthophylls and provide a valuable model for examining their uptake and conversion.