BACKGROUND: Lutein and zeaxanthin are antioxidant carotenoids that form the yellowish "macular pigment" in the center of the eye's retina. This pigment is believed to filter out harmful wavelengths of visible light and reduce free radical damage. A low macular pigment optical density is strongly associated with an increased risk of age-related macular degeneration.
Previous studies have shown that diets rich in lutein are associated with a lower risk of developing age-related macular degeneration. In addition, consumption of supplements containing lutein esters (a natural form of the antioxidant derived from marigolds) have been shown to increase lutein levels in the blood and macular pigment.
RESEARCH: In this report, researchers compared the absorption (in the blood and eye) of various daily doses of lutein and zeaxanthin, from 2.4 mg lutein, 5, 20 and 30 mg lutein from lutein esters and 30 mg zeaxanthin.
Four experiments were reported, involving young, middle-age, and elderly men and women. The numbers of subjects in the experiments ranged from 2 to 21, and the duration of supplementation ranged from 60 days to 6 months.
RESULTS: In response to taking lutein or lutein ester supplements, regardless of the dosage, all subjects had increased blood levels of lutein. Many of the subjects also had increased eye levels of lutein (as measured by macular pigment optical density), and these subjects tended to be those who took the higher 30 mg dosage of lutein from lutein esters daily (rather than only 2.4 mg lutein daily). There was considerable variability in lutein accumulation in the eyes, varying among individuals and, in some cases, varying between the eyes of the same individual.
Zeaxanthin blood levels increased to a much lower extent compared to the same dose of lutein. Likewise, in the eyes of the two subjects taking the zeaxanthin supplements, accumulation of zeaxanthin was not as efficient as lutein.
IMPLICATIONS: This study shows that lutein and zeaxanthin from supplements are absorbed, but that equivalent amounts of lutein tended to be better absorbed than zeaxanthin. Formulation differences such as carotenoid esterification and oil solubility are suggested explanations for these differences. In addition, higher dosages of lutein are more likely to increase the density of the macular pigment, which may reduce a person's risk of developing age-related macular degeneration. The researchers noted that long-term clinical trials will be needed to directly confirm the benefits of lutein and zeaxanthin.
Bone RA, Landrum JT, Guerra LH, et al, "Lutein and zeaxanthin dietary supplements raise macular pigment density and serum concentrations of these carotenoids in humans," Journal of Nutrition, 2003;133:992-998.
For the original abstract, visit: