Abstract
Dietary fat increases carotenoid bioavailability by facilitating their transfer to the aqueous micellar fraction during digestion. However, the specific effect of both quantity and type of dietary fat required for optimal carotenoid absorption remained unexplored. In the present study, the effect of amount and type of vegetable oils on carotenoid micellarization from carrot, spinach, drumstick leaves and papaya using in vitro digestion/Caco-2 cell model have been assessed. Although, dietary fat (0.5-10% w/w) significantly increased the micellarization of carotenoids from all the test foods, the extent of increase was determined by the food matrix (papaya > drumstick = spinach > carrot) and polarity of carotenoids (lutein > β-carotene = α-carotene > lycopene). Among the dietary fats tested the carotenoid micellarization was twofold to threefold higher with dietary fat rich in unsaturated fatty acids (olive oil = soybean oil = sunflower oil) compared to saturated fatty acids (peanut oil = palm oil > coconut oil). Intestinal cell uptake of lutein exceeded that of β-carotene from micellar fraction of spinach leaves digested with various oils. However, cellular uptake of β-carotene is depended on the carotenoid content in micellar fraction rather than the type of fat used. Together these results suggest that food matrix, polarity of carotenoids and type of dietary fat determines the extent of carotenoid micellarization from vegetables and fruits.