After consideration of all these interactions among carotenoids, the most likely explanation for the difference in bioavailability of b-carotene between fruit and vegetables was their different matrixes. More destructive methods are required for freeing b-carotene from chloroplasts within plant cells of dark-green, leafy vegetables than from chromoplasts of yellow and orange fruit where b-carotene is dissolved in oil droplets. In carrots, b-carotene is present as crystals, which dissolve very slowly. The subsequent incorporation of b-carotene into fat micelles for absorption may also be more difficult for b-carotene
from vegetables than from fruit because of the nature of the dietary fiber (27, 28), which may result in more entrapment of bcarotene before it can be incorporated into micelles