Calcium absorption from commonly consumed vegetables in healthy Thai women

The absorbability of calcium from ivy gourd, a green leafy vegetable (Coccinia grandix Voigt.) and winged bean young pods (Psophocarpus tetragonolobus [L] DC) were measured in 19 healthy adult women aged 20 to 45 y, in a 3-way, randomized-order, crossover design with an average calcium load of 100 mg and milk as the referent. The test meals were extrinsically labeled with 44Ca and given with rice as breakfast after an overnight fast. Absorption of calcium was determined on a blood sample drawn 5 h after ingestion of the test meal. Fractional calcium absorption (X+/- SD) was 0.391 +/- 0.128 from winged beans, 0.476 +/- 0.109 from ivy gourd, and 0.552 +/- 0.119 from milk. The difference in fractional calcium absorption for these 2 vegetables was significant (P < 0.05) and the fractional calcium absorption from these 2 vegetables were both significantly lower than from milk. The difference was partly accounted for by the phytate, oxalate, and dietary fiber content of the vegetables. However, calcium bioavailability of these 2 vegetables, commonly consumed among Thais, was relatively good compared to milk (71% to 86% of milk) and could be generally recommended to the public as calcium sources other than milk and Brassica vegetables.