For example, visual acuity can be markedly improved
through administration of anthocyanin pigments to animal
and human subjects, and the role of these pigments in
enhancing night vision or overall vision has been particularly
well documented [23]. Oral intake of anthocyanosides
from black currants resulted in significantly improved
night vision adaptation in human subjects [24],
and similar benefits were gained after administration of
anthocyanins from bilberries [25]. Three anthocyanins
from black currant stimulated regeneration of rhodopsin
(a G-protein-coupled receptor localized in the retina of
the eye), and formation of a regeneration intermediate
was accelerated by cyanidin 3-rutinoside [26]. These studies
strongly suggest that enhancement of rhodopsin regeneration
is at least one mechanism by which anthocyanins
enhance visual acuity.