Influence of feeding different vegetables on plasma levels of carotenoids,folate and vitamin C. Effect of disruption of the vegetable matrix

Carotenoids. folate and vitamin C may contribute to the observed beneficial effects of increased vegetable intake. Currently, knowledge on the bioavai lability of these compounds from vegetables is limited. We compared the eff icacy of different vegetables, at the same level of intake (i.e. 300 g/d), in increasing plasma levels of carotenoids, folate and vitamin C and we inv estigated if disruption of the vegetable matrix would enhance the bioavaila bility of these micronutrients. In an incomplete block design, sixty-nine v olunteers consumed a control meal without vegetables and three out of four vegetable meals (i.e. broccoli, green peas, whole leaf spinach, chopped spi nach; containing between 1.7 and 24.6 mg beta-carotene, 3.8 and 26 mg lutei n, 0.22 and 0.60 mg folate and 26 and 93 mg vitamin C) or a meal supplement ed with synthetic beta-carotene (33.3 mg). Meals were consumed for 4 d and fasting blood samples were taken at the end of each period. Consumption of the spinach-supplemented meal did not affect plasma levels of beta-carotene , although the beta-carotene content was 10-fold those of broccoli and gree n peas, which induced significant increases in plasma beta-carotene levels (28 (95 % CI 6.4, 55) % and 26 (95 % CI 2.6, 54) % respectively). The beta- carotene-supplemented meal increased plasma concentrations of p-carotene ef fectively (517 (95 % CI 409, 648) %). All vegetable meals increased the pla sma concentrations of lutein and vitamin C significantly. Broccoli and gree n peas were, when expressed per mg carotenoid consumed, also more effective sources of lutein than spinach. A significant increase in plasma folate co ncentration was found only after consumption of the spinach-supplemented me al, which provided the highest level of folate. Disruption of the spinach m atrix increased the plasma responses to both lutein (14 (95 % CI 3.7, 25) % ) and folate (10 (95 % CI 2.2, 18) %), whereas it did not affect the respon se to beta-carotene. We conclude that the bioavailabilities of beta-caroten e and lutein vary substantially among different vegetables and that the bio availabilities of lutein and folate from spinach can be improved by disrupt ion of the vegetable matrix.