William McCormack

Protein Supplementation at Breakfast and Lunch for 24 Weeks beyond Habitual Intakes Increases Whole-Body Lean Tissue Mass in Healthy Older Adults

BACKGROUND Key areas of research on the preservation of lean tissue mass (LTM) during aging are determinations of the protein requirement and optimal protein intake at meals. OBJECTIVE The aim of this study was to determine the effect of protein supplementation at breakfast and lunch for 24 wk beyond habitual intakes on whole-body LTM in healthy adults aged 50-70 y. METHODS In a single-blinded, randomized, controlled design, 60 healthy older men and women (aged 61 ± 5 y) with a body mass index (in kg/m(2)) of 25.8 ± 3.6 consumed either 0.165 g/kg body mass of a milk-based protein matrix (PRO) or an isoenergetic, nonnitrogenous maltodextrin control (CON) at breakfast and midday meals, the lower protein-containing meals of the day, for 24 wk. Dual-energy X-ray absorptiometry was used to measure the change in LTM. RESULTS After the intervention, protein intake in the PRO group increased from 0.23 ± 0.1 to 0.40 ± 0.1 g/kg for breakfast and from 0.31 ± 0.2 to 0.47 ± 2 g/kg for the midday meal. In response, LTM increased by 0.45 (95% CI: 0.06, 0.83) kg in the PRO group compared with a decrease of 0.16 (95% CI: -0.49, 0.17) kg in the CON group (P = 0.006). Appendicular LTM accounted for the majority of the difference in LTM, increasing by 0.27 (95% CI: 0.05, 0.48) kg in the PRO group compared with no change in the CON group (P = 0.002). CONCLUSIONS Protein supplementation at breakfast and lunch for 24 wk in healthy older adults resulted in a positive (+0.6 kg) difference in LTM compared with an isoenergetic, nonnitrogenous maltodextrin control. These observations suggest that an optimized and balanced distribution of meal protein intakes could be beneficial in the preservation of lean tissue mass in the elderly. This trial was registered at clinicaltrials.gov as NCT02529124.

Angiogenin levels and ANG genotypes: dysregulation in amyotrophic lateral sclerosis.

Objective To determine whether 5 single nucleotide polymorphisms (SNPs) associate with ALS in 3 different populations. We also assessed the contribution of genotype to angiogenin levels in plasma and CSF. Methods Allelic association statistics were calculated for polymorphisms in the ANG gene in 859 patients and 1047 controls from Sweden, Ireland and Poland. Plasma, serum and CSF angiogenin levels were quantified and stratified according to genotypes across the ANG gene. The contribution of SNP genotypes to variance in circulating angiogenin levels was estimated in patients and controls. Results All SNPs showed association with ALS in the Irish group. The SNP rs17114699 replicated in the Swedish cohort. No SNP associated in the Polish cohort. Age- and sex-corrected circulating angiogenin levels were significantly lower in patients than in controls (p<0.001). An allele dose-dependent regulation of angiogenin levels was observed in controls. This regulation was attenuated in the ALS cohort. A significant positive correlation between CSF plasma angiogenin levels was present in controls and abolished in ALS. Conclusions ANG variants associate with ALS in the Irish and Swedish populations, but not in the Polish. There is evidence of dysregulation of angiogenin expression in plasma and CSF in sporadic ALS. Angiogenin expression is likely to be important in the pathogenesis of ALS.

Evaluation of the antioxidant capacity of a milk protein matrix in vitro and in vivo in women aged 50–70 years

Abstract Bovine milk proteins have emerged as a novel, dairy-based source of dietary antioxidants and a component of a nutritional strategy to maintain muscle mass during ageing. The aim of this study was to characterise the in vitro antioxidant capacity (AOC) of a milk-based protein matrix (MPM) before and after simulated gastrointestinal digestion (SGID) and determine whether plasma AOC was similarly modified in vivo following acute ingestion of the MPM in healthy 50–70 years old women. To achieve this, the AOC of the MPM was measured by the oxygen radical absorbance capacity (ORAC) assay prior to and following SGID. In parallel, plasma obtained from women prior to and for 3 h following ingestion of the MPM was analysed ex vivo for change in AOC to evaluate the translation in vivo. SGID of the MPM increased AOC by ∼35% (27,365 ± 2152 versus 42,592 ± 2299 μmol TE/100 g dw; p < 0.05). Sampled ex vivo, ingestion of the MPM increased fasting plasma AOC by ∼23% (10,952 ± 751 to 13,519 ± 800 μmol TE/L; p < 0.05). These data provide preliminary evidence of an association between the change in the ORAC-based measurement of AOC of an MPM subjected to simulated digest in vitro and the change in plasma AOC following ingestion of the MPM sampled ex vivo from healthy elderly women.

An in vivo microdialysis characterization of the transient changes in the interstitial dialysate concentration of metabolites and cytokines in human skeletal muscle in response to insertion of a microdialysis probe.

Skeletal muscle has recently been described as an endocrine organ, capable of releasing cytokines and regulators of metabolism. Microdialysis of the interstitial space of skeletal muscle enables analysis of the release of such cytokines. The purpose of this study was to determine the transient changes in concentration of metabolites and cytokines in human skeletal muscle in a 7h period following the insertion of a microdialysis probe. In total, sixteen microdialysis catheters were inserted into the vastus lateralis of male participants (age 26.2±1.35y, height 180.8±3.89cm, mass 83.9±3.86kg, BMI 25.7±0.87kgm(-2), body fat 26.1±3.0%). Serial samples were analyzed by micro-enzymatic and multiplexed immunoassay. Muscle interstitial glucose and lactate levels remained stable throughout, amino acid concentrations stabilized after 2.5h, however, insertion of a microdialysis catheter induced a 29-fold increase in peak IL-6 (p<0.001) and 35-fold increase in peak IL-8 concentrations (p<0.001) above basal levels 6h post insertion. In contrast to stable amino acid, glucose and lactate concentrations after 2h, commonly reported markers of tissue homeostasis in in vivo microdialysis, the multi-fold increase in IL-6 and IL-8 following insertion of a microdialysis catheter is indicative of a sustained disturbance of tissue homeostasis.

Muscle strength can better differentiate between gradations of functional performance than muscle quality in healthy 50–70 y women

Highlights • Muscle strength is a better predictor of functional performance than muscle quality.• Extended gait speed is a functionally relevant measure in healthy 50–70 y women.• Healthy adults need functional assessments that allow performance toward maximum.

Body composition analysis of inter-county Gaelic athletic association players measured by dual energy X-ray absorptiometry

ABSTRACT Gaelic Football and Hurling are two sporting codes within the Gaelic Athletic Association. The purpose of this study was to report the body composition phenotype of inter-county Gaelic athletic association players, comparing groups by code and field position. 190 senior, male, outfield inter-county players (144 hurlers and 46 Gaelic footballers) were recruited. Stature and body mass was measured, estimates of three components of body composition, i.e. lean mass, fat mass and bone mineral content was obtained by dual energy X-ray absorptiometry (DXA), and normative data for Gaelic athletic association athletes by code and position was compared. Other than in the midfield, there was limited difference in body composition between codes or playing position. Stature-corrected indices nullified any existing group differences between midfielders for both codes. Further comparisons with a non-athletic control group (n = 431) showed no difference for body mass index (BMI); however, the athletic group has a lower fat mass index, with a greater lean mass in accounting for the matched BMI between groups. In addition to providing previously unknown normative data for the Gaelic athletic association athlete, a proportional and independent tissue evaluation of body composition is given.

A comparison of the insulinotropic and enterogastric response to ingestion of an equivalent quantity of maltodextran and whey protein

. It was hypothesized that the insulinotropic action of whey proteinmay, in part, be mediated via the secretion of the enterogastric hormones, represented by glucagon-like peptide-1 (GLP-1).The present paper reports on the post-prandial response of plasma glucose, insulin and GLP-1 to feeding maltodextran and anequivalent quantity of whey protein. With ethical approval and informed consent four young, healthy subjects ( n = 4, age 25(2.8) y, BMI21.8(1.1) kg/m

Seasonal changes in body composition of inter-county Gaelic Athletic Association hurlers

ABSTRACT Longitudinal change in body composition for elite-level inter-county hurlers was reported over a single season and four consecutive seasons. Body composition measured by dual-energy x-ray absorptiometry (DXA) of 66 senior, male, outfield players was obtained. Four successive measurements were taken: off-season (OFF1), pre-season (PRE), mid-season (MID) and the off-season of the following season (OFF2). A subsample of 11 hurlers were measured at all time points over 4 consecutive seasons. DXA-derived estimates of fat and lean mass were normalised to stature for analysis (kg∙m‒2); data are (mean [lower: upper, 95% confidence interval]). A concurrent increase of lean mass (0.31 [0.19: 0.43] kg∙m‒2) and loss of fat mass occurred (−0.38 [−0.50: −0.26] kg∙m‒2) OFF1 to PRE. Lean mass accrual was maintained PRE to OFF2 while the initial loss of fat mass was restored MID to OFF2 (0.52 [0.40: 0.64] kg ∙ m‒2), with the trunk acting as the primary region of change. Over the four seasons, a net increase of lean mass was observed (~ 0.9 [0.4: 1.4] kg per annum) with a negligible overall change for fat mass over time. However, the cycling of fat mass (OFF to PRE and MID to OFF) within each season was recurrent season-to-season.