Assertion: carotenoid | /r/HasProperty | vitamin a precursors
Facets:
Source sentences:
text: We anticipate that some of these previously inexplicable patterns will begin to make sense as biologists include vitamin A pathways in their studies, more carefully consider the fundamental differences between carotenoids that are vitamin A precursors and those that are not, and appreciate the different interdependencies of retinoids, carotenoids, and oxidative state that are involved with different forms of ornamental coloration.
text: Some carotenoids are precursors of vitamin A, and prevent human age-related macular degeneration.