In vitro accessibility of β-carotene from cooked Sri Lankan green leafy vegetables and their estimated contribution to vitamin A requirement

Vitamin A deficiency is an important issue for public health in Sri Lanka, where pro-vitamin A carotenoids from green leafy vegetables provide most of the dietary vitamin A. The objective of this study was to analyse the beta-carotene content of seven types of green leafy vegetables and calculate the contribution of one traditionally cooked portion to the recommended daily allowance (RDA) of retinol. The total amount and in vitro accessibility of beta-carotene were determined using HPLC. The in vitro method simulates the conditions in the human intestinal tract. The all-trans-beta-carotene content in the fresh blanched vegetables ranged from 149 mu g g(-1) dry weight (DW) in leaves of Alternanthera sessilis (mukunuwanna) to 565 mu g g(-1) DW in Amaranthus caudatus (thampala). One portion (100g) of green leaves cooked without fat (coconut) only contributed from 140 to 180 mu g mg(-1) of the recommended daily allowance. A. sessilis, Centella asiatica (gotukola), Spinacea oleracea (nivithi) and A. caudatus, cooked with coconut fat contributed 140-680 mu g mg(-1). However, stir-fried or 'malluma' preparations (with coconut products) of Sesbania grandiflora (kathurumurunga) and Manihot esculenta (manioc) may provide more than 1.59-4.37 times the RDA of retinol. These results show that not only the choice of green leaves used but also the addition of fat while cooking is of great importance. (c) 2005 Society of Chemical Industry.