Fat-soluble nutrient concentrations in different layers of human cataractous lens

Purpose. Recent epidemiologic studies suggest that differential risk for ca taract in different areas of the lens may be related to intake of carotenoi ds, retinol, and tocopherol. Nevertheless, there is little information abou t differential localization of these nutrients in the lens. To determine th e spatial distribution of fat-soluble nutrients within the lens, we determi ned levels of these nutrients in the epithelium/outer cortex vs. inner cort ex/nucleus. Methods. Concentrations of carotenoids, retinol, and tocopherol were determ ined in the epithelial/cortical (younger, more metabolically active tissue) and nuclear (older, less metabolically active) layers of human cataractous lenses (n = 7, 64-75 yr) by reverse-phase high-performance liquid chromato graphy (HPLC). Results. Lutein/zeaxanthin was the only carotenoid, which was detected, in human lens. Consistent with prior reports, no beta-carotene or lycopene wer e detected. Concentrations of lutein/zeaxanthin, tocopherol, and retinol in epithelium/cortex tissue were approximately 3-, 1.8-, and 1.3-fold higher than in the older lens tissue. Specifically, the epithelial/cortical lens l ayer, comprising about half of the tissue, contains 74 % of lutein/zeaxanth in (44 ng/g wet wt), 65 % of a-tocopherol (2227 ng/g wet wt), and 60 % of r etinol (30 ng/g wet wt). Conclusions. The data suggest that upon development and aging, there is dif ferential localization of these nutrients. The data are also consistent wit h a protective role of these nutrients against oxidative damage in the epit helium and cortex of the human lens.