Absorption and tissue distribution of zeaxanthin and lutein in rhesus monkeys after taking Fructus lycii (Gou Qi Zi) extract.Invest Ophthalmol Vis Sci. 2001 Feb; 42(2):466-71.IO
To study serum and tissue levels of zeaxanthin and lutein after feeding rhesus monkeys an extract of Fructus lycii (gou qi zi).
A carotenoid-containing fraction (P1) from an extract of F. lycii (equivalent to 2.2 mg zeaxanthin) was fed to three rhesus monkeys for 6 weeks as a daily dietary supplement through a nasogastric tube. Three other monkeys were fed with the vehicle (olive oil) similarly for 4 weeks as a control. Another three animals were fed with normal diet only. All animals were killed 4 hours after the last dose. Samples of serum, liver, spleen, brain, and retina were analyzed for zeaxanthin and lutein by high-pressure liquid chromatography.
The basal levels of zeaxanthin and lutein in the monkey sera were 3.0 +/- 1.6 ng/ml (range, 2.3-4.8) and 31.5 +/- 12.2 ng/ml (range, 22.3-42.5), respectively. Serum levels of zeaxanthin and lutein in the P1-fed group were significantly higher than those of vehicle control (P<0.05). Besides the retina, the liver had the highest zeaxanthin and lutein levels, whereas the levels in the brain were undetectable. P1 supplement appeared to elevate zeaxanthin levels in liver and spleen. The level of lutein was higher than that of zeaxanthin in the maculae of rhesus monkeys. However, there were no detectable carotenoids in the peripheral and the equatorial regions of the monkey retina. P1 treatment elevated zeaxanthin density but not lutein in the macula.
Serum levels and macular density of zeaxanthin was raised by feeding a carotenoid-containing fraction of F. lycii. Therefore, F. lycii is a good dietary source of zeaxanthin supplement.