Absorption kinetics are a key factor regulating postprandial protein metabolism in response to qualitative and quantitative variations in protein intake

Abstract

We have previously demonstrated that increasing the habitual protein intake widened the gap in nutritional quality between proteins through mechanisms that are not yet fully understood. We hypothesized that the differences in gastrointestinal kinetics between dietary proteins were an important factor affecting their differential response to an increased protein intake. To test this hypothesis, we built a 13-compartment model providing integrative insight into the sequential dynamics of meal nitrogen (Nm) absorption, splanchnic uptake, and metabolism, and subsequent peripheral transfer and deposition. The model was developed from data on postprandial Nm kinetics in certain accessible pools, obtained from subjects having ingested a (15)N-labeled milk or soy protein meal, after adaptation to normal (NP) or high (HP) protein diets. The faster absorption of Nm after soy vs. milk caused its earlier and stronger splanchnic delivery, which favored its local catabolic utilization (up to +30%) and limited its peripheral accretion (down to -20%). Nm absorption was also accelerated after HP vs. NP adaptation, and this kinetic effect accounted for most of the HP-induced increase (up to +20%) in splanchnic Nm catabolic use, and the decrease (down to -25%) in peripheral Nm anabolic utilization. The HP-induced acceleration in Nm absorption was more pronounced with soy than with milk, as were the HP effects on Nm regional metabolism. Our integrative approach identified Nm absorption kinetics, which exert a direct and lasting impact on Nm splanchnic catabolic use and peripheral delivery, as being critical in adaptation to both qualitative and quantitative changes in protein intake.

The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption

“…In addition to digestibility issues, it was reported that the dietary protein-derived AAs from the plant-based proteins soy and wheat are more readily converted to urea when compared with the ingestion of milk proteins (56)(57)(58)(59). This would ultimately lower the potential of these plant-based protein sources to stimulate the skeletal muscle anabolic response.…”

“…As described previously, plant-based protein sources are generally lower in lysine and/or methionine than are animal-based protein sources (Table 3, Figure 2). This may impair the postprandial MPS response after the ingestion of plant-based protein sources when compared with animal-based proteins (56)(57)(58)(59). Thus, similar to leucine fortification, it may be hypothesized that adding lysine and/or methionine to plant-based proteins is a useful strategy to improve their anabolic properties.…”

The challenge of diabetes in Asia

“…The model calculations are fairly complex but allow one to predict the kinetics of dietary nitrogen in the body (Juillet et al, 2006). Both the amino acid profi le of the protein and the kinetics of amino acid delivery to the blood can affect the postprandial splanchnic and peripheral uptake of amino acid in humans (Deglaire et al, 2009b;Fouillet et al, 2000Fouillet et al, , 2001Fouillet et al, , 2002bFouillet et al, , 2003Fouillet et al, , 2009Juillet et al, 2008). Increasing protein intake increases splanchnic catabolic use while splanchnic catabolic use and peripheral anabolic use are inversely affected (Fouillet et al, 2009).…”

Linear compartmental systems. I. kinetic analysis and derivation of their optimized symbolic equations

“…. , δ; r ≤ v) are given by: (22) and each submatrix indicated as 0 in Expression (21), which is located in the r th row and vth column of matrix K , has n v rows and n r columns, while all its elements are zeros. It may also possible that one or more of the submatrices denoted as M r,v (r > v if r ≤ f ) may be a matrix r × v, whose elements are all zeros.…”