Selenium content of wheat for bread making in Scotland and the relationship between glutathione peroxidase (EC 1.11.1.9) levels in whole blood and bread consumption.

The selenium content of the 1989 harvest of wheat used for bread making in Scotland ranged from 0.028 microgram/g dry weight for home-grown wheat to 0.518 microgram/g for Canadian wheat. The tonnage values indicate that 13.8% of the wheat used in bread making came from Canada. This reflects in a calculated dietary intake of 31 micrograms/d which is well below the recommended levels of 70 and 55 micrograms for adult males and females respectively (National Research Council, 1989). The average glutathione peroxidase (EC 1.11.1.9) level in 478 samples of human whole blood was 6.08 (SE 0.065) units/ml. This increased to 6.65 (SE 0.321) in sixty-two subjects consuming brown or wholemeal bread but was unaffected by oily fish consumption. Analysis of a small number of samples of whole milk, eggs and meat indicated slightly higher concentrations than previously published values but this trend was insufficient to compensate for the lower cereal provision of Se.