Interindividual variability in response to protein and fish oil supplementation in older adults: a randomized controlled trial

Abstract

Background Precision nutrition is highly topical. However, no studies have explored the interindividual variability in response to nutrition interventions for sarcopenia. The purpose of this study was to determine the magnitude of interindividual variability in response to two nutrition supplementation interventions for sarcopenia and metabolic health, after accounting for sources of variability not attributable to supplementation. Methods A 24 week, randomized, double‐blind, placebo‐controlled trial tested the impact of leucine‐enriched protein (LEU‐PRO), LEU‐PRO plus long‐chain n‐3 PUFA (LEU‐PRO+n‐3) or control (CON) supplementation in older adults (n = 83, 71 ± 6 years) at risk of sarcopenia. To estimate the true interindividual variability in response to supplementation (free of the variability due to measurement error and within‐subject variation), the standard deviation of individual responses (SDR) was computed and compared with the minimally clinically important difference (MCID) for appendicular lean mass (ALM), leg strength, timed up‐and‐go (TUG), and serum triacylglycerol (TG) concentration. Clinically meaningful interindividual variability in response to supplementation was deemed to be present when the SDR positively exceeded the MCID. The probability that individual responses were clinically meaningful, and the phenotypic, dietary, and behavioural determinants of response to supplementation were examined. Results The SDR was below the MCID for ALM (LEU‐PRO: −0.12 kg [90% CI: −0.38, 0.35], LEU‐PRO+n‐3: −0.32 kg [−0.45, 0.03], MCID: 0.21 kg), TUG (LEU‐PRO: 0.58 s [0.18, 0.80], LEU‐PRO+n‐3: 0.73 s [0.41, 0.95], MCID: 0.9 s) and TG (LEU‐PRO: −0.38 mmol/L [−0.80, 0.25], LEU‐PRO+n‐3: −0.44 mmol/L [−0.63, 0.06], MCID: 0.1 mmol/L), indicating no meaningful interindividual variability in response to either supplement. The SDR exceeded the MCID (19 Nm) for strength in response to LEU‐PRO (25 Nm [−29, 45]) and LEU‐PRO+n‐3 (23 Nm [−29, 43]) supplementation but the effect was uncertain, evidenced by wide confidence intervals. In the next stage of analysis, similar proportions of participant responses were identified as very likely, likely, possibly, unlikely, and very unlikely to represent clinically meaningful improvements across the LEU‐PRO, LEU‐PRO+n‐3, and CON groups (P > 0.05). Baseline LC n‐3 PUFA status, habitual protein intake, and numerous other phenotypic and behavioural factors were not determinants of response to LEU‐PRO or LEU‐PRO+n‐3 supplementation. Conclusions Applying a novel, robust methodological approach to precision nutrition, we show that there was minimal interindividual variability in changes in ALM, muscle function, and TG in response to LEU‐PRO and LEU‐PRO+n‐3 supplementation in older adults at risk of sarcopenia.

Effects of Omega-3 Fatty Acid Supplementation on Skeletal Muscle Mass and Strength in Adults: A Systematic Review

“…Of all studies, 4 were 2-arm RCTs ( Table 3 ). The mean age of the study participants was between 63 and 77.4 years [ 9 34 35 36 ]. As studies have investigated the effect of omega-3 fatty acids in combination with other ingredients or foods (e.g., fruit juice), the control group for intervention in these studies corresponded to a formula or food without omega-3 fatty acids.…”

“…While most studies utilizing protein supplementation with omega-3 are beneficial, one study reported no significant effects of EPA and DHA on skeletal muscle mass and strength. The study was conducted in a manner similar to the aforementioned studies with older adults aged ≥ 65 years [ 35 ] and defined sarcopenia or low handgrip strength according to the European Working Group on Sarcopenia in Older People 2010 (EWGSOP1) criteria [ 1 ]. A 10.6 g whey protein and 3.1 g of total leucine, or protein with omega-3 fatty acids containing 0.8 g EPA and 1.1 g DHA were supplied to the participants for 24 weeks.…”

Inter‐individual variability in redox and performance responses after antioxidant supplementation: A randomized double blind crossover study

“…Similar approaches have been implemented in some recent interesting original studies regarding the effect of an endurance training protocol on various muscle and whole-body adaptations, 26 the impact of sprint interval exercise training on fasting and postprandial insulin sensitivity adaptations, 27 and the effect of protein and fish oil supplementation on biochemical, morphological and functional characteristics in older adults. 29 For the aims of the present study, we designed a two-treatment, two-period AB/BA crossover design. 41 We assessed potential carry-over effects as previously suggested, 42 data was analyzed using a linear mixed-effects model, 17 and individual probabilities of response along with the population proportions of response were also calculated.…”

“…To our knowledge, this is the first study to investigate inter‐individual variability in the responses after a nutritional intervention within the context of exercise physiology and sports nutrition. Similar approaches have been implemented in some recent interesting original studies regarding the effect of an endurance training protocol on various muscle and whole‐body adaptations, 26 the impact of sprint interval exercise training on fasting and postprandial insulin sensitivity adaptations, 27 and the effect of protein and fish oil supplementation on biochemical, morphological and functional characteristics in older adults 29 . For the aims of the present study, we designed a two‐treatment, two‐period AB/BA crossover design 41 .…”

“…). Based on these concerns, more suitable methodological frameworks and statistical analyses have been proposed 15,22–24 and applied in some very recent original studies and meta‐analyses 25–30 . It is noteworthy that most of these studies do not support the idea of significant inter‐individual variability in response to an intervention, as evidenced by the larger variation observed in the responses of the control group compared to the intervention group.…”