The modulation of metabolic stress responses by ω-3 fatty acids: molecular to whole-body perspectives

Abstract

Although there are indications that n-3 PUFA may be beneficial for different aspects of physiological function, particularly in situations of metabolic stress, little is known about their potential modulatory effects in healthy, young adults. In Chapter 2, we investigated whether 4g/d n-3 PUFA (FO) for 4 weeks prior to and during 2-week, 40% energy restriction (ER), could preserve lean mass. ER facilitated a 3.2kg loss of body mass, of which 1.1kg lean mass, which was unaffected by n-3 PUFA supplementation. In addition, n-3 PUFA did not influence whole-body changes in energy metabolism or muscle function. In Chapter 3, we measured the phosphorylation status of mTOR and rpS6 in muscle from healthy males, as a proxy for muscle protein synthesis, to determine the effect of n-3 PUFA supplementation for 4 weeks on muscle anabolic signalling during 2-week, 40% ER. We demonstrated that muscle anabolic signalling during ER, as the change in phosphorylation status of mTOR and rpS6, was unaffected by n-3 PUFA in the basal state. RpS6 status was significantly potentiated by n-3 PUFA following resistance exercise and consumption of 10g protein, during ER, while mTOR status was not. N-3 PUFA did not significantly change the expression of genes related to muscle development and autophagy. In Chapter 4, we demonstrated that n-3 PUFA supplementation ingested 1 hour before exercise does not elicit worthwhile improvements in exercise function and time trial performance in trained cyclists. Using a Bayesian statistical approach, we determined there was a low-to-very low probability of improvements in exercise function. Collectively, the findings of this thesis suggest n-3 PUFA supplementation in healthy males does not elicit wortwhile improvements in whole-body physiology and muscle function.