Manganese absorption from mangold (Beta vulgaris): comparison of intrinsic and extrinsic labels

The validity of the use of extrinsic labeling for studies of manganese absorption in man was evaluated using a test meal containing Beta vulgaris intrinsically labeled with ⁵⁴Mn to which ⁵²Mn was added extrinsically. Whole body retention of the two isotopes was measured in a whole body counter during days 7-25 after administration of the test meal to six subjects. No difference in level of retention or rate of excretion was observed for the two isotopes. The calculated absorption (X = SD) was 6.0 ± 3.4% and 6.2 ± 2.9% for ⁵⁴Mn and ⁵²Mn, respectively, resulting in a ⁵⁴Mn : ⁵²Mn ratio for fractional absorption from the test meal of 0.95 ± 0.14 (X ± SD). These results demonstrate that extrinsic labeling with radioisotopes of manganese is a valid method for measurement of manganese absorption from vegetables when studied in humans.