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

Recent epidemiologic studies suggest that differential risk for cataract in different areas of the lens may be related to intake of carotenoids, retinol, and tocopherol. Nevertheless, there is little information about differential localization of these nutrients in the lens. To determine the spatial distribution of fat-soluble nutrients within the lens, we determined levels of these nutrients in the epithelium/ outer cortex vs. inner cortex/nucleus.

Concentrations of carotenoids, retinol, and tocopherol were determined 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 chromatography (HPLC).

Lutein/zeaxanthin was the only carotenoid, which was detected, in human lens. Consistent with prior reports, no beta-carotene or lycopene were 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 layer, comprising about half of the tissue, contains 74% of lutein/zeaxanthin (44 ng/g wet wt), 65% of alpha-tocopherol (2227 ng/g wet wt), and 60% of retinol (30 ng/g wet wt).

The data suggest that upon development and aging, there is differential localization of these nutrients. The data are also consistent with a protective role of these nutrients against oxidative damage in the epithelium and cortex of the human lens.