Absorbability of Calcium from Brassica Vegetables: Broccoli, Bok Choy, and Kale

Absorption of calcium from three intrinsically labeled Brassica sp. vegetables was measured in 15 normal women in a three-way randomized design. The test load of calcium was about 83 mg for each source. Fractional calcium absorption from broccoli averaged 0.478 ± 0.089, from bok choy stems, 0.519 ± 0.089, from bok choy leaves, 0.520 ± 0.074, and from kale 0.527 ± 0.091. These differences were both absolutely small and statistically insignificant. Mean absorbability of milk calcium ingested at the same load has been previously shown to be 0.463 ±0.095. This value is slightly but significantly lower than the average value for the Brassica sources combined (0.514 ± 0.090). Thus, Brassicu vegetable sources exhibit excellent calcium bioavailability.