Abstract
Fish-derived proteins, particularly fish protein hydrolysates (FPH), offer potential as high-quality sources of dietary protein, whilst enhancing economic and environmental sustainability. This study investigated the impact of a blue whiting-derived protein hydrolysate (BWPH) on aminoacidaemia in vivo and skeletal muscle anabolism in vitro compared with whey protein isolate (WPI) and an isonitrogenous, non-essential amino acid (NEAA) control (0.33 g·kg−1·body mass−1) in an ex vivo, in vitro experimental design. Blood was obtained from seven healthy older adults (two males, five females; age: 72 ± 5 years, body mass index: 24.9 ± 1.6 kg·m2) in three separate trials in a randomised, counterbalanced, double-blind design. C2C12 myotubes were treated with ex vivo human serum-conditioned media (20%) for 4 h. Anabolic signalling (phosphorylation of mTOR, p70S6K, and 4E-BP1) and puromycin incorporation were determined by immunoblotting. Although BWPH and WPI both induced postprandial essential aminoacidaemia in older adults above the NEAA control, peak and area under the curve (AUC) leucine and essential amino acids were more pronounced following WPI ingestion. Insulin was elevated above baseline in WPI and BWPH only, a finding reinforced by higher peak and AUC values compared with NEAA. Muscle protein synthesis, as measured by puromycin incorporation, was greater after incubation with WPI-fed serum compared with fasted serum (P = 0.042), and delta change was greater in WPI (P = 0.028) and BWPH (P = 0.030) compared with NEAA. Myotube hypertrophy was greater in WPI and BWPH compared with NEAA (both P = 0.045), but was similar between bioactive conditions (P = 0.853). Taken together, these preliminary findings demonstrate the anabolic potential of BWPH in vivo and ex vivo, thus providing justification for larger studies in older adults using gold-standard measures of acute and chronic MPS in vivo.
Highlights
Post hoc testing revealed that leucine did not differ at baseline between conditions
After 30 min, leucine was significantly elevated in both whey protein isolate (WPI) and blue whiting-derived protein hydrolysate (BWPH) compared with the non-essential amino acids (NEAAs) control (d = 2.87 and d = 8.21, respectively), and these differences persisted until the conclusion of the trial
After 60 min, leucine was significantly higher in WPI compared with BWPH (d = 2.23) and remained so until 180 min
Summary
The decline in muscle strength, quality, and physical function with age, otherwise known as sarcopenia [1], is associated with physical disability, an increased risk of falls, decreased quality of life, hospitalisation, and mortality [2,3,4,5,6]. Dietary protein is recognised as an important strategy to manage and prevent sarcopenia, offering substantial therapeutic benefits when applied synergistically with resistance exercise [7,8,9,10]. 31–50% of non-institutionalised older adults fail to meet the Recommended Daily Allowance (RDA). Older people are less responsive to a low-dose amino acid (AA) bolus, such “anabolic resistance” may be overcome with greater protein or essential amino acid (EAA) For protein of 0.8 g·kg−1 ·body mass−1 ·day−1 [11], despite the fact that several authors have advocated intakes in excess of 1.0 g·kg−1 ·body mass−1 ·day−1 for this population [12,13,14,15].
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