Circulating Amino Acid Concentration after the Consumption of Pea or Whey Proteins in Young and Older Adults Affects Protein Synthesis in C2C12 Myotubes

Abstract

As older adults tend to reduce their intake of animal-source proteins, plant-source proteins may offer valuable resources for better protein intake. The aim of this study was to assess whether the pea proteins can be used to achieve blood amino acid levels that stimulate muscle protein synthesis. We measured variations in plasma amino acid concentrations in young and older adults given pea (NUTRALYS^® S85 Plus) or whey proteins either alone or in a standardized meal. The effect of amino acid concentrations on protein synthesis in C2C12 myotubes was determined. In terms of results, plasma amino acid concentrations reflected the difference between the amino acid contents of whey and pea proteins. Blood leucine showed a greater increase of 91 to 130% with whey protein compared to pea protein, while the opposite was observed for arginine (A greater increase of 147 to 210% with pea compared to whey). Culture media prepared with plasmas from the human study induced age-dependent but not protein-type-dependent changes in myotube protein synthesis. In conclusion, pea and whey proteins have the same qualities in terms of their properties to maintain muscle protein synthesis. Pea proteins can be recommended for older people who do not consume enough animal-source proteins.

Keywords: aging; amino acids; pea protein; protein synthesis; skeletal muscle; whey protein.

Figure 1

Study design.

Figure 2

Changes in leucine concentrations in plasmas from young and older participants after the PP, WP, MPP, and MWP dietary treatments. To calculate the plasma leucine concentration change, the baseline value measured at T0 was subtracted from the other values measured at the different time-course points. Results are expressed as means ± SEM. PP: pea protein solution; WP: whey protein solution; MPP: standardized meal plus pea protein solution; MWP: standardized meal plus whey protein solution.

Figure 3

The p70 S6 kinase phosphorylation state and protein synthesis in C2C12 myotubes conditioned with media containing plasmas prepared from the human study. After 5 days of differentiation, C2C12 myotubes were treated with 10% human plasma in HBSS media for 4 h in the presence of 1 µM puromycin. We compared two plasma samples from each participant at each dietary treatment and calculated the difference between the two values, i.e., the value obtained with plasma samples at the peak plasma leucine concentration (Cmax) minus the value obtained with plasma samples prepared at the baseline timepoint (T0). The graphs plot differences for (A) the activation state of p70 S6 kinase and (C) the incorporation of puromycin in neosynthesized peptides. The tables display p values for the main effects and interactions following a 3-way repeated measures ANOVA for differences in (B) changes in the activation state of p70 S6 kinase and (D) changes in the incorporation of puromycin in neosynthesized peptides after the PP, WP, MPP, and MWP dietary treatments. Results are expressed as means ± SEM. Significant main effects or interactions are in bold (p < 0.05). PP: pea protein solution; WP: whey protein solution; MPP: standardized meal plus pea protein solution; MWP: standardized meal plus whey protein solution.