Absorption of selenium from wheat, garlic, and cod intrinsically labeled with Se-77 and Se-82 stable isotopes

There is limited information on the absorption of selenium from different foods in humans because of technical difficulties associated with isotopic labeling of dietary selenium. Wheat, garlic, and cod fish were intrinsically labeled with Se-77 or Se-82 stable isotopes. Labeled meals were fed in random order to 14 adults, with a minimum washout period of six weeks between each test meal. Apparent absorption was measured as luminal loss using a fecal monitoring technique over an 8-day period. Plasma appearance of the isotope was measured at 7, 24, and 48 hours post-ingestion. Selenium absorption (+/- SD) was significantly higher (p < 0.001) from wheat (81.0 +/- 3.0%) and garlic (78.4 +/- 13.7%) than from fish (56.1 +/- 4.3%). Lowest plasma concentration was observed after the fish meal at all three time points, with a peak at 24 hours, whereas wheat produced the highest plasma concentration at all three time points and peaked at 7 hours. Selenium absorption from wheat and garlic was higher than from fish, and inter-individual variation was low. Form of selenium and food constituents appear to be key determinants of post-absorptive metabolism.