In Vitro Evidence of α‑Linolenic Acid Ethyl Ester Hydrolysis and Transesterification in the Gastrointestinal Tract in the Presence of Acylglycerols

Abstract

Omega-3 polyunsaturated fatty acids (n-3 PUFA), such as α-linolenic acid (ALA), are crucial for human health. Although n-3 PUFAs in food are mainly in triacylglycerol (TAG) form, they are often provided as ethyl esters (EE) in supplements. Previous research has demonstrated improved postprandial bioavailability of n-3 PUFAs in the EE form when coingested with fat, potentially due to transesterification during digestion. To shed light on the bioavailability improvement, this study investigated the influence of triolein and 2-monoolein on the digestion of ALA-EE using an in vitro model, employing 1H NMR spectroscopy and liquid chromatography combined with mass spectrometry. ALA-EE hydrolysis increased from 6.6 to 22–29% with acylglycerols, reaching 55.8% after longer incubation with 2-monoolein. Transesterification of ALA in acylglycerols was observed, especially after incubation with 2-monoolein, but its correlation with ALA-EE hydrolysis remained ambiguous. Therefore, the bioavailability improvements were attributed to the facilitating effect of TAG lipolysis products on ALA release.