Consumption of a Specially-Formulated Mixture of Essential Amino Acids Promotes Gain in Whole-Body Protein to a Greater Extent than a Complete Meal Replacement in Older Women with Heart Failure

Abstract

Heart failure in older individuals is normally associated with a high body mass index and relatively low lean body mass due to, in part, a resistance to the normal anabolic effect of dietary protein. In this study we have investigated the hypothesis that consumption of a specially-formulated composition of essential amino acids (HiEAAs) can overcome anabolic resistance in individuals with heart failure and stimulate the net gain of body protein to a greater extent than a commercially popular protein-based meal replacement beverage with greater caloric but lower essential amino acid (EAA) content (LoEAA). A randomized cross-over design was used. Protein kinetics were determined using primed continuous infusions of L-(2H5)phenylalanine and L-(2H2)tyrosine in the basal state and for four hours following consumption of either beverage. Both beverages induced positive net protein balance (i.e., anabolic response). However, the anabolic response was more than two times greater with the HiEAA than the LoEAA (p < 0.001), largely through a greater suppression of protein breakdown (p < 0.001). Net protein accretion (g) was also greater in the HiEAA when data were normalized for either amino acid or caloric content (p < 0.001). We conclude that a properly formulated EAA mixture can elicit a greater anabolic response in individuals with heart failure than a protein-based meal replacement. Since heart failure is often associated with obesity, the minimal caloric value of the HiEAA formulation is advantageous.

Keywords: aging; anabolic response; protein quality; sarcopenia; stable isotope tracer.

Conflict of interest statement

Wolfe and Wei are inventors of US patent US 9,597,367 B2. Methods for improving muscle and heart function. Wolfe has received honoraria from Trivita, Inc. There are no other potential conflicts of interest.

Figures

Figure 1

Experimental protocol. Each subject was studied twice. In one study the test drink was a specially-formulated composition of essential amino acids (HiEAA), and in the other study the test drink was a commercially available drink with lower essential amino acid content (LoEAA).

Figure 2

Plasma enrichments of infused tracers (Phe M+5/M+0 and Tyr M+2/M+0) and one (Tyr M+4/M+0) derived from Phe M+5 through hydroxylation. Samples were taken before and following consumption either the HiEAA or the LoEAA after the 180 min sample was collected. Values (n = 7) are expressed as mean ± standard error of the mean (SEM). TTR, tracer to tracee ratio; M+0 is the most abundant form of naturally occurring Phe or Tyr; M+i (e.g., M+2, M+4, and M+5) is heavier than M+0 by i mass unit.

Figure 3

Total changes in whole-body protein kinetics (protein synthesis (PS), protein breakdown (PB), and net protein balance (NB)) from basal post-absorptive values following either the HiEAA or the LoEAA. *** Significantly different between meals, p < 0.001. Values (n = 7) are expressed as mean ± SEM.

Figure 4

Net protein accretion efficiency. Efficiency was determined by dividing net protein accretion (g protein over 240 min) by either the amino acid content, multiplied by 100 (left) or by the caloric content (right) of the HiEAA or the LoEAA. *** Significantly different from the LoEAA, p < 0.001. Values (n = 7) are expressed as mean ± SEM.

Figure 5

Time course responses and total area under curves (AUC) of plasma concentrations of essential amino acids (EAAs), non-essential amino acids (NEAAs), leucine, and branched chain amino acids (leucine, isoleucine, valine, BCAAs) following either consumption of the HiEAA or the LoEAA. There were significant effects for treatment, time, and treatment-by-time interaction for EAAs, leucine, and BCAAs (for all, p < 0.001) as well as NEAAs (for all, p < 0.02). Values (n = 8) are expressed as mean ± SEM. *** significantly different from the LoEAA, p < 0.001.