Dietary epoxy fatty acids are absorbed in healthy women

BACKGROUND: Epoxy fats in the diet may adversely affect human health. There are no data on the absorption of these fats in humans. METHODS: Triglycerides were synthesized containing two U-13C-labelled monoepoxy or diepoxy stearic acid molecules. Apparently healthy women consumed a standardized fatty meal (30 g fat) containing either 20 mg monoepoxy or 25 mg diepoxy fat (n = 6 and n = 7, respectively). Plasma lipid [U-13C]monoepoxy and diepoxy stearate concentrations were determined (0-24 h) by gas chromatography-mass spectrometry. RESULTS: Plasma triglycerides increased from 1.05 +/- 0.12 to 1.83 +/- 0.13 mmol L-1 (n = 6) and from 1.10 +/- 0.19 to 1.41 +/- 0.27 mmol L-1 (n = 7) (both P < 0.001). Plasma [U-13C]monoepoxy and diepoxy stearate levels increased to 0.18 +/- 0.07 micromol L-1 (n = 6) and to 0.08 +/- 0.03 micromol L-1 (n = 7), respectively. Monoepoxy triglyceride was better absorbed than diepoxy triglyceride: 17 +/- 4 vs. 8 +/- 1% of dose (determined from area under curve (plasma 13C) normalized to that of absorbed triglycerides (plasma 12C); P < 0.02 after log transformation). The absorption of monoepoxy- and diepoxy-labelled triglycerides was related to that of normal triglycerides (r = 0.80, P < 0.05 and r = 0.91, P < 0.001, respectively). CONCLUSIONS: Monoepoxy fats are better absorbed than diepoxy fats in women (17 +/- 4 vs. 8 +/- 1% of dose, P = 0.02). This difference in absorption is important when considering the relative toxicity of epoxidized material in the food chain.