Docosahexaenoate-enriched fish oil and medium chain triglycerides shape the feline plasma lipidome and synergistically decrease circulating gut microbiome-derived putrefactive postbiotics

Matthew I. Jackson,Catherine Mounier,Dennis E. Jewell

doi:10.1371/journal.pone.0229868

Abstract

The purpose of this study was to examine the influence of medium-chain fatty acid-containing triglycerides (MCT), long-chain polyunsaturated fatty acid-containing triglycerides, and their combination on the plasma metabolome of cats (Felis catus), including circulating microbiome-derived postbiotics. After a 14-day lead-in on the control food, cats were randomized to one of four foods (control, with 6.9% MCT, with fish oil [FO; 0.14% eicosapentaenoate, 1.0% docosahexaenoate], or with FO+MCT; n = 16 per group) for 28 days. Analysis of plasma metabolites showed that the addition of FO and MCT led to synergistic effects not seen with either alone across a number of lipid classes, including fatty acids, acylcarnitines, and acylated amines including endocannabinoids. Notably, the FO+MCT group had an increase in ketone body production relative to baseline and beyond that seen with MCT alone. N-acyl taurines, the accumulation of which has been implicated in the onset of type 2 diabetes, were significantly decreased in the FO+MCT group. Significant decreases in the gut microbiome-derived postbiotic classes of indoles/indolic sulfates and phenols/phenolic sulfates were observed only the FO+MCT group. Overall, the combination of MCT and FO led to number of changes in plasma metabolites that were not observed with either oil alone, particularly in postbiotics.

Highlights

Dietary fatty acids esterified in triglyceride form are an important source of nutritional energy and consist of diverse carbon chain lengths and degrees of unsaturation
Differences between LCPUT and medium-chain fatty acid-containing triglycerides (MCT) are apparent from the outset of their catabolism; MCTs are hydrolyzed to medium-chain saturated fatty acids (MCFAs) by pancreatic lipase with an avidity exceeding that for long
CAPTEX-355 (ViaChem Inc, Plano, TX, USA) was chosen as the source of MCT as it was enriched for caprylate (C8:0) over caprate (C10:0) and caproate (C6:0) and contained negligible amounts of the transition fatty acids laurate (C12:0) and myristate (C14:0), which are typically high in coconut and palm oils and do not exhibit the same biochemical properties as the canonical MCFAs caproate (C6:0), caprylate (C8:0), and caprate (C10:0)

Summary

Introduction

Dietary fatty acids esterified in triglyceride form are an important source of nutritional energy and consist of diverse carbon chain lengths and degrees of unsaturation. Found at orthogonal extremes of these characteristics are the medium-chain saturated fatty acids (MCFAs) and the long-chain polyunsaturated fatty acids (LCPUFAs), each of which is typically consumed in triglyceride form (MCT and LCPUT, respectively). Differences between LCPUT and MCT are apparent from the outset of their catabolism; MCTs are hydrolyzed to MCFAs by pancreatic lipase with an avidity exceeding that for long.

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