ABSTRACT
In an incomplete block design, sixty-nine volunteers consumed a control meal without vegetables and three out of four, vegetable meals (i.e. broccoli, green peas, whole leaf spinach, chopped spinach; containing between 1.7 and 24.6 mg β-carotene, 3.8 and 26 mg lutein, 0.22 and 0.60 mg folate, and 26 and 93 mg vitamin C) or a meal supplemented with synthetic β-carotene (33.3 mg) (van der Hof et al., 1999). Meals were consumed for four days and fasting blood samples were taken at the end of each period. Consumption of the spinach-supplemented meal did not affect plasma levels of β-carotene, although the β-carotene content was 10-fold those for broccoli and green peas, which induced signifi cant increases in plasma β-carotene levels (28 and 26%, respectively). The β-carotene-supplemented meal increased plasma concentrations of β-carotene effectively. All vegetable meals increased the plasma concentrations of lutein and vitamin C. A signifi cant increase in plasma folate concentration was found only after consumption of the spinach-supplemented meal, which provided the highest level of folate. Disruption of the spinach matrix increased the plasma responses to both lutein and folate, whereas it did not affect the response to β-carotene. The authors conclude that the bioavailabilities of lutein and folate from spinach are improved by disruption of the vegetable matrix. However, proper selection of superior cultivars is important. Though increasing intakes of carotenoid-rich plant-foods can increase serum carotenoid concentrations and macular pigment optical density in most, not all, individuals. Kopsell et al. (2006) studied to, (a) characterize tissue lutein and β-carotene concentrations in carotenoid-rich spinach cultigens, and (b) determine serum carotenoid and macular pigment optical density responses in human subjects consuming spinach cultigens differing in tissue lutein and β-carotene concentrations. Thirteen spinach cultigens were evaluated for carotenoid accumulation over two consecutive growing seasons. ‘Springer’ (8.4 and 6.5 mg 100-1 gram of fresh mass for lutein and β-carotene, respectively) and ‘Spinner’ (12.1 and 9.2 mg 100-1 gram of fresh mass for lutein and β-carotene, respectively) spinach cultigens were selected for a dietary intervention study and represented low-and highlutein concentrations. The high-lutein ‘Spinner’ and low-lutein ‘Springer’ spinach treatment groups consisted of 10 subject volunteers ingesting fi ve 50-gram spinach servings per week during a 12-week intervention. Average serum lutein concentrations increased by 22% from baseline for subjects consuming low-lutein spinach. Subjects consuming high-lutein spinach showed increases of 33% in serum lutein from baseline. Average macular pigment optical density did not change for the low-lutein treatment group; however, subjects in the high-lutein group demonstrated increases in macular pigment optical density. This study demonstrates that serum carotenoid and macular pigment optical density are determined by lutein concentrations present in the spinach matrix. Results emphasize the role of
cultigen selection among vegetable crops in determining the phytochemical effects on human health.
