Lack of effects of fish oil supplementation for 12 weeks on resting metabolic rate and substrate oxidation in healthy young men: A randomized controlled trial.

Sebastian Jannas-Vela,Kaitlin Roke,Lawrence L Spriet,Stephanie Boville,David M Mutch,Conrad P Earnest

doi:10.1371/journal.pone.0172576

Abstract

Fish oil (FO) has been shown to have beneficial effects in the body via incorporation into the membranes of many tissues. It has been proposed that omega-3 fatty acids in FO may increase whole body resting metabolic rate (RMR) and fatty acid (FA) oxidation in human subjects, but the results to date are equivocal. The purpose of this study was to investigate the effects of a 12 week FO supplementation period on RMR and substrate oxidation, in comparison to an olive oil (OO) control group, in young healthy males (n = 26; 22.8 ± 2.6 yr). Subjects were matched for age, RMR, physical activity, VO2max and body mass, and were randomly separated into a group supplemented with either OO (3 g/d) or FO containing 2 g/d eicosapentaenoic acid (EPA) and 1 g/d docosahexaenoic acid (DHA). Participants visited the lab for RMR and substrate oxidation measurements after an overnight fast (10–12 hr) at weeks 0, 6 and 12. Fasted blood samples were taken at baseline and after 12 weeks of supplementation. There were significant increases in the EPA (413%) and DHA (59%) levels in red blood cells after FO supplementation, with no change of these fatty acids in the OO group. RMR and substrate oxidation did not change after supplementation with OO or FO after 6 and 12 weeks. Since there was no effect of supplementation on metabolic measures, we pooled the two treatment groups to determine whether there was a seasonal effect on RMR and substrate oxidation. During the winter season, there was an increase in FA oxidation (36%) with a concomitant decrease (34%) in carbohydrate (CHO) oxidation (p < 0.01), with no change in RMR. These measures were unaffected during the summer season. In conclusion, FO supplementation had no effect on RMR and substrate oxidation in healthy young males. Resting FA oxidation was increased and CHO oxidation reduced over a 12 week period in the winter, with no change in RMR.Trial Registration: ClinicalTrials.gov NCT02092649

Highlights

Omega-3 polyunsaturated fatty acids are a family of fatty acids (FAs) characterized by unique physical and structural properties that influences several aspects of metabolism and physiology in the human body [1,2]
red blood cells (RBCs) levels of eicosapentanoic acid (EPA) were increased in the fish oil (FO) group from 0.6 to 3.1% of total FAs (p < 0.001)
The primary finding of this well-controlled study was that 12 weeks of FO supplementation had no effect on resting metabolic rate (RMR) and substrate oxidation in young, healthy males

Summary

Introduction

Omega-3 polyunsaturated fatty acids are a family of fatty acids (FAs) characterized by unique physical and structural properties that influences several aspects of metabolism and physiology in the human body [1,2]. Omega-3 FAs bind to peroxisome proliferator-activated nuclear receptors (PPARs), altering the expression of proteins involved in fat metabolism [12], such as fatty acid translocase/cluster of differentiation 36 [13], uncoupling protein-3 (UCP-3) [14] and CPT-1 [10]. These adaptations suggest that supplementation with EPA and DHA may increase whole body RMR and promote a shift towards fatty acid (FA) oxidation

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