The vitamin A nutritional value of banana and plantain fruits depends not only on the concentration of provitamin A carotenoids but also on the relative proportion of the individual provitamin A carotenoids present. This is because individual provitamin A
carotenoids compounds have different vitamin A activities, due to differences in their chemical structures. The relative vitamin A activity of 13-cis-b-carotene has been estimated as 53% of all-transb- carotene (Schieber and Carle, 2005), while trans alpha carotene has only one half of the biological activity of all-trans-b-carotene (Fraser and Bramley, 2004; Trumbo et al., 2003). Lutein has no vitamin A activity. From a nutritional viewpoint, fruit/foods with higher alltrans- b-carotene contents are preferred as all-trans-b-carotene is the provitamin A carotenoids with the highest vitamin A nutrition value.