Changes of blood selenium in New Zealand adults with time and importation of Australian wheat.

Blood selenium (Se) in residents of Hamilton, in the North Island of New Zealand, varied during 1973 to 1980 with maximum and minimum values of 87 and 57 ng/ml Se. These changes are consistent with values calculated from variations in dietary intake of Se of wheat products from the blending of New Zealand wheat (11 ng/g Se) with imported Australian wheat (150 ng/g Se). Se concentrations found in wheat products such as bread and flour were also in agreement with similarly calculated values. In contrast, the blood Se in residents of Dunedin and Tapanui, in the South Island of New Zealand, did not change with importation of wheat and coincided with the Hamilton minimum. This is attributed both to the similarity of Se levels in the associated soils, and to the absence of importation of Australian wheat into the South Island, which produces over 90% of the New Zealand wheat crop.