Metabolic fate (absorption,β-oxidation and deposition) of long-chainn-3 fatty acids is affected by sex and by the oil source (krill oil or fish oil) in the rat

Abstract

The effects of krill oil as an alternative source of n-3 long-chain PUFA have been investigated recently. There are conflicting results from the few available studies comparing fish oil and krill oil. The aim of this study was to compare the bioavailability and metabolic fate (absorption, β-oxidation and tissue deposition) of n-3 fatty acids originating from krill oil (phospholipid-rich) or fish oil (TAG-rich) in rats of both sexes using the whole-body fatty acid balance method. Sprague-Dawley rats (thirty-six male, thirty-six female) were randomly assigned to be fed either a krill oil diet (EPA + DHA + DPA = 1·38 mg/g of diet) or a fish oil diet (EPA + DHA + DPA = 1·61 mg/g of diet) to constant ration for 6 weeks. The faeces, whole body and individual tissues were analysed for fatty acid content. Absorption of fatty acids was significantly greater in female rats and was only minimally affected by the oil type. It was estimated that most of EPA (>90 %) and more than half of DHA (>60 %) were β-oxidised in both diet groups. Most of the DPA was β-oxidised (57 and 67 % for female and male rats, respectively) in the fish oil group; however, for the krill oil group, the majority of DPA was deposited (82-83 %). There was a significantly greater deposition of DPA and DHA in rats fed krill oil compared with those fed fish oil, not due to a difference in bioavailability (absorption) but rather due to a difference in metabolic fate (anabolism v. catabolism).

Differences in long chain polyunsaturates composition and metabolism in male and female rats

“…Our findings of greater accumulation of 22:6n-3 and 22:5n-6 in female rat plasma are in general agreement with a variety of observations related to DHA tissue content in rats [25, 37–40]. Similarly in human subjects, higher erythrocyte DHA levels were observed in women of childbearing age by Smit et al [17] and Magnusardottir et al [23], as well as in postmenopausal women after hormone replacement therapy [21, 22].…”

Genome-Wide Association Study for Serum Omega-3 and Omega-6 Polyunsaturated Fatty Acids: Exploratory Analysis of the Sex-Specific Effects and Dietary Modulation in Mediterranean Subjects with Metabolic Syndrome

“…Some PUFA are specifically required for reproduction [104]. It has been reported that PUFA concentrations are higher in females than in males during pregnancy and there are some studies showing sex-specific effects for some PUFA in determining several outcomes [68][69][70][71][72][73][74]140,141]. Although this is still an emerging field, the promotion of research investigating sex-specific differences [142] could provide more information regarding sex-specific effects on gene*sex interactions in determining PUFA levels for a more personalized nutrition.…”

“…Another issue in these meta-analyses is the lack of focus on potential sex-specific differences, as well as overall dietary pattern modulating PUFA interventions. Regarding sex, several human studies as well as research in animal models [66][67][68][69][70][71][72][73] have reported some differences between males and females on analyzing the PUFA effects on diverse cardiovascular risk phenotypes. However, more specific research remains to be done in order to better understand the potential differences.…”

Dietary ALA from Spinach Enhances Liver n‐3 Fatty Acid Content to Greater Extent than Linseed Oil in Mice Fed Equivalent Amounts of ALA

“…Longer experiments in different types of animals to ensure fatty acid levels reach equilibrium and a comprehensive fatty acid analysis of blood lipids (plasma, erythrocytes, or leukocytes) and other tissues are needed. For further insight on absorption and metabolism of n-3 PUFA from glycolipids, intake and excretion measurements as well as tracer studies using isotope-labeled ALA are needed [39][40][41].…”