A meal with mixed soy/whey proteins is as efficient as a whey meal in counteracting the age-related muscle anabolic resistance only if the protein content and leucine levels are increased

Abstract

With aging, skeletal muscle becomes resistant to the anabolic effect of dietary proteins and sarcopenia develops.

Post Meal Energy Boluses Do Not Increase the Duration of Muscle Protein Synthesis Stimulation in Two Anabolic Resistant Situations

“…In the present manuscript, we studied two different muscle wasting conditions for which we have clearly described an anabolic resistance in skeletal muscle following food intake. In these two studies, we showed that whey, a rapidly digested protein rich in leucine, was more efficient than casein at the same protein content for (re)initiating an anabolic response, mainly by increasing muscle protein synthesis postprandially [9,10]. Thus, some of these results which represent the “control” groups in these manuscripts have been already published.…”

“…The gastrocnemius muscles were rapidly removed, weighed and freeze-clamped in liquid nitrogen, and stored at −80 °C. Regarding the muscle protein synthesis measurement, 40 min before the sacrifice, animals were injected intravenously with L-valine (150 μmol per 100 g body weight) containing 100% L-[1- 13 C] valine (Euriso-Top) (see [9] for the detailed protocol).…”

“…It is now well-established that the postprandial anabolic response in skeletal muscle occurs through the stimulation of protein synthesis initiated by increased essential amino acid bioavailability, whereas the decrease in proteolysis mainly occurs through the stimulation of insulin secretion in response to feeding [2,3]. Although decreased physical activity has been identified as a cause, muscle atrophy has also been explained by the presence of anabolic resistance following food intake in several physio-pathological catabolic states as diverse as aging, cancer, and disuse [4,5,6,7,8,9,10]. In each case, increasing dietary protein intake above the current recommended dietary allowances (RDA at 0.8 g/kg/day) [11] has been proposed to overcome the anabolic resistance observed.…”

“…In each case, increasing dietary protein intake above the current recommended dietary allowances (RDA at 0.8 g/kg/day) [11] has been proposed to overcome the anabolic resistance observed. Among dietary proteins, rapidly digested and leucine-rich proteins (i.e., whey) have been shown to be the most efficient for the acute stimulation of muscle protein synthesis during aging, disuse or glucocorticoid treatment when compared to casein, a protein with lower leucine content and whose digestion rate is slower [9,12,13,14]. However, when given in the long-term, whey proteins alone do not appear to be an optimal nutritional strategy to prevent or slow down muscle wasting during aging [15,16] or catabolic states [10,17,18,19].…”

Whey for Sarcopenia; Can Whey Peptides, Hydrolysates or Proteins Play a Beneficial Role?

“…Phosphorylation of Akt and other mTOR signalling proteins (4E-BP1 and p70S6k) were significantly elevated at 60 min post-ingestion of whey and leucine compared to leucine alone (Akt, 4E-BP1) or the fasted state (Akt, 4E-BP1 and p70S6k). Jarzaguet et al [ 63 ] fed aged rats (20 months) whey proteins 144 g/kg feed containing leucine 16.2 g/kg. Phosphorylation status of Akt and other mTOR biomarkers (S6K1 and S6) were significantly elevated after ingestion of whey bolus compared to casein or soy with some diet by time interactions.…”