Glycidol exposure evaluation of humans who have ingested diacylglycerol oil containing glycidol fatty acid esters using hemoglobin adducts

Glycidol fatty acid esters (GEs) have been found as impurities in refined edible oils including diacylglycerol (DAG) oil, and concerns of possible exposure to glycidol (G), a known animal carcinogen, during digestion have been raised. We previously measured N-(2,3-dihydroxy-propyl)valine (diHOPrVal), a G hemoglobin adduct, for DAG oil exposed and non-exposed groups and showed there was no significant difference between them. In the present study, we conducted an additional analysis to verify the outcome of the previous report. The first experiment was designed as a matched case-control study to adjust variables with an increased sample size. The average levels of diHOPrVal were 6.9 pmol/g-globin (95%CI: 4.9–9.0) for 14 DAG oil exposed subjects and 7.3 pmol/g-globin (95%CI: 6.1–8.5) for 42 non-exposed volunteers, and no significant difference in levels was found between the two groups. In a second experiment, we compared the adduct levels of 12 DAG oil exposed subjects before and after discontinuing use of DAG oil, and found there was no significant change in diHOPrVal levels (from 7.1 ± 1.1 to 7.5 ± 1.4 pmol/g-globin). These results suggest that there was no increased exposure to G for humans who ingested DAG oil daily, although the evaluated population was limited.