Genetic Variability for Lutein Concentrations in Leafy Vegetable Crops Can Influence Serum Carotenoid Levels and Macular Pigment Optical Density in Human Subjects

Leafy vegetables are important sources of dietary carotenoids and rank highest for reported lutein concentrations. We have shown previously that lutein concentrations can range from 4.8 to 13.4 mg/100 g fresh weight (FW) for kale (Brassica oleracea L.), from 6.5 to 13.0 mg/100 g FW for spinach (Spinacia oleracea L.), and from 4.1 to 8.3 mg/100 g FW for basil (Ocimum basilicum L.) cultigens. Lutein and zeaxanthin are typically the only carotenoids present in the eye, where they are responsible for the yellow pigmentation referred to as macular pigment. Macular pigment conveys antioxidant and photo-protective functions that help prevent the onset of aging eye diseases. Increasing intakes of carotenoid-rich foods can increase serum carotenoids and macular pigment in some, but not all individuals. Our main objective was to assess the dietary impact of lutein after consumption of spinach differing in tissue lutein concentrations (8.4 vs. 12.1 mg lutein/100 g FW). Research compared blood serum carotenoid profiles and macular pigment optical densities (MPOD) in human subjects consuming the different spinach products. Heterochromatic flicker photometry determined MPOD responses. Average blood serum lutein concentrations increased significantly from the baseline to the end of a 12-week intervention in subjects consuming the high-lutein spinach. Average MPOD did not change for the no-spinach (control) or low-lutein spinach group. The high-lutein spinach group demonstrated increases in MPOD at 30’ eccentricity between the baseline and 12-weeks. Results emphasize the role of cultigen selection among vegetable crops in determining phytochemical effects on human health.