Lutein supplements are not bioavailable in the Mongolian gerbil while consuming a diet with or without cranberries

Lutein is a carotenoid that may be involved in the prevention of macular degeneration and is available as supplements. Cranberries are a potential "functional food" due to anti-adhesion and antioxidant properties. This study was designed to determine the bioavailability of lutein supplements in Mongolian gerbils, as prior studies have focused on beta-carotene, and to investigate any interactions between a lutein supplement and a diet containing cranberries. Gerbils (n = 28) were divided into treatment groups: lutein + cranberry; lutein + control; cottonseed oil + cranberry; and cottonseed oil + control. The lutein supplement (50 microg lutein in oil) was delivered orally for 14 days, and then blood, livers, and eyes were collected. Samples were analyzed by high-performance liquid chromatography (HPLC) and total antioxidant status was determined. Serum and liver were analyzed for lutein, retinol, and alpha-tocopherol. Serum lutein concentrations were extremely low in all four groups. Serum total antioxidants did not differ (p > 0.2) among diet groups. Serum retinol concentrations were significantly lower in the cranberry groups (p = 0.0024). In conclusion, gerbils are able to thrive on a high cranberry diet. However, this study showed that lutein, as a daily supplement in oil, is not bioavailable in Mongolian gerbils.