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.
Highlights
Heart failure is a global public health concern, affecting approximately 6%–10% of individuals over the age of 65 worldwide [1]
The mechanism underlying the suppression of protein breakdown in response to HiEAA was not likely an insulin response, as we have previously shown that insulin concentration is not increased in response to essential amino acid (EAA) ingestion [14]
We have previously shown that the addition of non-essential amino acids (NEAAs) to a mixture of EAAs provides no benefit in terms of protein synthesis [35]
Summary
Heart failure is a global public health concern, affecting approximately 6%–10% of individuals over the age of 65 worldwide [1]. A diminished response to the normal anabolic effect of nutrient consumption (anabolic resistance), with regard to dietary protein, may be an important aspect of the loss of muscle mass in heart failure. A nutritional solution to the problem of loss of muscle mass in heart failure, even in obese individuals, would be of great value. Such a composition would stimulate the net gain of body protein, but would do so with minimal caloric intake. We have tested the hypothesis that a low-calorie EAA-based dietary supplement will induce a significantly greater gain in whole-body net protein balance than a conventional meal replacement beverage targeting support of heart failure patients. The comparison is significant in terms of the responses of protein synthesis and breakdown to a conventional serving, and because of the considerable differences in the caloric intake associated with the two nutritional approaches
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