In Vitro and In Vivo Digestibility of Soybean, Fish, and Microalgal Oils, and Their Influences on Fatty Acid Distribution in Tissue Lipid of Mice.

Bo-Ram Na,Jeung-Hee Lee

doi:10.3390/molecules25225357

Abstract

The digestion rates of microalgal (docosahexaenoic acid, DHA, 56.8%; palmitic acid, 22.4%), fish (DHA, 10.8%; eicosapentaenoic acid, EPA, 16.2%), and soybean oils (oleic, 21.7%; linoleic acid, 54.6%) were compared by coupling the in vitro multi-step and in vivo apparent digestion models using mice. The in vitro digestion rate estimated based on the released free fatty acids content was remarkably higher in soybean and fish oils than in microalgal oil in 30 min; however, microalgal and fish oils had similar digestion rates at longer digestion. The in vivo digestibility of microalgal oil (91.49%) was lower than those of soybean (96.50%) and fish oils (96.99%). Among the constituent fatty acids of the diet oils, docosapentaenoic acid (DPA) exhibited the highest digestibility, followed by EPA, DHA, palmitoleic, oleic, palmitic, and stearic acid, demonstrating increased digestibility with reduced chain length and increased unsaturation degree of fatty acid. The diet oils affected the deposition of fatty acids in mouse tissues, and DHA concentrations were high in epididymal fat, liver, and brain of mice fed microalgal oil. In the present study, microalgal oil showed lower in vitro and in vivo digestibility, despite adequate DHA incorporation into major mouse organs, such as the brain and liver.

Highlights

DHA (C22:6) is a major n-3 polyunsaturated fatty acid (PUFA) that is uniquely concentrated in the brain, nervous tissues, and retina
(8.8%), showing that this oil is rich in the n-3 fatty acids (FAs) of EPA and DHA; the main FAs at the sn-2 position include palmitic (20.0%), EPA (17.3%), palmitoleic (12.3%), DHA (19.0%), and myristic acid (9.8%)
Microalgal oil mainly contains DHA (56.8%), docosapentaenoic acid (DPA) (12.3%), and palmitic (22.4%), whereas EPA is present in trace amounts (0.6%); at the sn-2 position, it contains DHA (67.3%), DPA (15.2%), and palmitic acid

Summary

Introduction

DHA (C22:6) is a major n-3 polyunsaturated fatty acid (PUFA) that is uniquely concentrated in the brain, nervous tissues, and retina. Fish oil contains EPA (13.3%) and DHA (8.9%), while microalgal oil extracted from Schizochytrium sp. Dietary oil is emulsified with bile acid and the sn-1,3 fatty acids (FAs) of triacylglycerol (TAG) are hydrolyzed by sn-1,3 specific pancreatic lipases, and absorbed by small intestinal mucosal cells in the form of 2-monoacylglycerol (MAG) and free fatty acids (FFAs) [7,8]. Oil is composed of different types of FAs and the position of FAs in the glycerol backbone of TAG varies, leading to differences in digestibility, absorption, and bioavailability after ingestion. Microalgal oil contains a large amount of DHA and when ingested, it has a low hydrolysis rate. The digestibility and absorption rate of ingested microalgal oil is low, resulting in reduced bioavailability of DHA

Methods

Results

Conclusion