Xanthophyll carotenoids are more bioaccessible from fruits than dark green vegetables

The objectives of this study were to compare the in vitro bioaccessibility of carotene and xanthophyll carotenoids from a range of fruits and vegetables. β-Carotene, lycopene, lutein, zeaxanthin, and β-cryptoxanthin contents of 4 fruits (orange, kiwi, red grapefruit, and honeydew melon) and 4 vegetables (spinach, broccoli, red pepper, and sweet potato) were determined by high-performance liquid chromatography. Bioaccessibility (transfer of carotenoids from digestate to micelles) is defined as the amount of the ingested compound available in the gastrointestinal tract for absorption. Raw fruits and vegetables were subjected to an in vitro digestion procedure, as previously described; and the micellar fractions were prepared by ultracentrifugation. There was generally better transfer of carotenoids to the micelles from fruits rather than vegetables. When present, the xanthophyll carotenoids (lutein, zeaxanthin, and β-cryptoxanthin) were highly bioaccessible from fruits, ranging from 50% to 100%. The dark green vegetables (spinach and broccoli) had lower lutein bioaccessibility (19%-38%) in comparison with fruit (100%-109%). The differences in bioaccessibility between the fruits and vegetables indicate that certain carotenoids are potentially more available from fruit for absorption by gastrointestinal cells. It was observed that the higher the carotenoid content of a fruit or vegetable digestate, the lower the transfer into the micelles. Data are in line with previously published in vitro and in vivo studies in this area. This in vitro digestion method allows a rapid estimation of carotenoid bioaccessibility from different food samples.