DIFFERENT BIOAVAILABILITY IN HUMANS OF WHEAT AND FISH SELENIUM AS MEASURED BY BLOOD-PLATELET RESPONSE TO INCREASED DIETARY SE

The bioavailabilities of selenium (Se) from Se-rich fish species and Se-rich wheat were compared in a study involving 32 healthy volunteers. Initial serum Se values were 109 +/- 16 mug/L (mean +/- SD). For 6 wk, one group (n = 11) included Se-rich bread in their diet, bringing daily average intake of Se up to 135 +/- 25 mug/d. Another group (n = 11) consumed Se-rich fish daily (average Se intake: 115 +/- 31 mug/d), whereas the control group (n = 10) ate their normal diet, providing 77 +/- 25 mug Se/d. Serum Se increased by 17% (P < 0.01), and platelet Se increased by 30% (P < 0.01) in the wheat group. Although platelet Se decreased by 11% in the fish group, no changes in serum and platelet Se in the fish or control group reached statistical significance. Glutathione peroxidase (EC 1.11.1.9; GSH-Px) activity in serum and platelets did not change during the study, nor did platelet mercury (Hg) content. Since the dietary intake of Hg, arsenium (As), and fatty acids could not satisfactorily explain the lack of response in the fish group, the results are indicative of low bioavailability of fish Se in humans. At present, wheat Se seems to be the most important factor contributing to the body stores of Se in this study population.