Applied Nutritional InvestigationsAttenuation of the protein wasting associated with bed rest by branched-chain amino acids☆
Introduction
Bed rest is associated with decreased nitrogen balance, with skeletal muscle being the major site of the protein loss. The protein loss associated with bed rest is a problem common to all ages, although the consequences are most serious for the elderly because their recuperative powers are weakest.1 Protein loss is always of concern because a loss of 35–40% protein is fatal.2 With intermediate losses, resistance to infection increases as protein depletion increases.3, 4, 5 In the case of bed rest there is also the loss of physical strength that follows a period of immobility.6, 7
Magnetic resonance imaging (MRI) and dual photon x-ray absorptiometry (DPA) measurements on subjects after periods of bed rest ranging from 1–17 wk have shown that most of the protein loss is from the legs and lower back.7, 8, 9, 10 Recovery after 17 wk of bed rest was not rapid; it took 8 wk.8 Thus, it is important in the treatment and rehabilitation of patients with a variety of conditions to institute specific measures to reduce the protein loss that occurs with bed rest. Clearly physical activity would be effective, but physical activity by bed-rest patients is usually not practical.
A bed-rest study by Stuart found that increasing the protein content of the diet from 0.6 g protein kg/d to 1.0 g protein kg/d prevented both the nitrogen loss associated with 7 d of bed rest and any decrease in the whole body protein synthesis rate.11 May and Buse suggested that many of the advantages of giving high protein doses were in fact due to the increased amounts of the branched-chain amino acids (BCAAs) provided.12 The objective of this study was to test this hypothesis by adding supplemental BCCAs to diet during bed rest.
Section snippets
Materials and methods
A total of 19 healthy subjects (17 males, 2 females, age range 22–37 y) were recruited from the surrounding community. Subject characteristics are given in Table I For the protection of human subjects, informed consent for this study was obtained in accordance with the policies of the Temple University Health Science Center and the University of Medicine and Dentistry of New Jersey—School of Osteopathic Medicine Institutional Review Boards.
Results
The data, including subject characteristics, are summarized in Table I. Five subjects were dropped from the study, two because of non-compliance and three because their dietary intakes fell outside the desired limits. Because of the need to use a pair-feeding approach, actual activity factors ranged between 1.02 and 1.45 with a mean of 1.28. Activity factors and their variance were the same for both groups (Table I).
Overall N retention was greater for the BCAA-fed group (P < 0.03, Table I),
Energy balance
The subjects in this study were probably in positive energy balance during bed rest. Energy intake was about 28 kcal · kg−1 · d−1 (Table I). Using the doubly labeled water method to measure the energy expenditure on nine subjects during bed rest, Gretebeck et al.15 found the mean energy expenditure to be 24.2 + 0.8 kcal · kg−1 · d−1. A similar study by Goran et al.16 measured the energy expenditure of five healthy men who although not confined to bed were severely limited in the amount of
Acknowledgements
We would like to thank our subjects for their participation and the staff of the GCRC at Temple University Health Sciences Center for their excellent care of the subjects.
References (28)
Nutrition and immunity: lessons from the past and new insights into the future. 1990 McCollum Award Lecture
Am J Clin Nutr
(1991)- et al.
Effect of dietary protein on bed-rest-related changes in whole-body-protein synthesis
Am J Clin Nutr
(1990) - et al.
Nitrogen balance, concepts and techniques
- et al.
Overnight branched chain amino acid infusion causes sustained suppression of muscle proteolysis
Metabolism
(1995) General aspects of the regulation of protein metabolism by diet and by hormones
- et al.
Excess energy and nitrogen balance at protein intakes above the requirement level in young men
Am J Clin Nutr
(1988) - et al.
Nitrogen balance studies in humans: long-term effect of high nitrogen intake on nitrogen accretion
J Nutr
(1979) - et al.
Mechanisms and nutritional significance of metabolic responses to altered intakes of protein and amino acids with reference to nutritional adaptation in humans
Am J Clin Nutr
(1990) Nutrition and the elderly. A general overview
J Am Coll Nutr
(1984)- et al.
The biology of human starvation
(1950)
Nutrition and the respiratory system
Crit Care Med
Nutrition and Infection
Ann Rev Nutr
Physiological adaptations to weightlessness: effects on exercise and work performance
Exer Sport Sci Rev
Calf muscle area and strength changes after 5 weeks of horizontal bed rest
Am J Sports Med
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2014, Advances in Food and Nutrition ResearchCitation Excerpt :Results obtained show that protein administration prior to or during sleep is followed by normal protein digestion and absorption and results in a significant increase of overnight muscle protein synthesis. A number of studies have demonstrated that prolonged supplementation with essential amino acids (11–50 g per day; equivalent to 22–100 g per day of dietary protein) during a period of 6–28 days of bed rest reduces the loss of muscle mass (Paddon-Jones, Sheffield-Moore, Urban, et al., 2004; Stein, Schluter, Leskiw, & Boden, 1999). However, it should be reminded that such large and prolonged supplementation with essential amino acids is an expensive strategy, which could be less practical than manipulating dietary protein intake.
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This study was supported by NIH grants RO1 AG14078 (TPS), RO1 AG 07988 (GB), R01 AA 10221 (GB), and RR-349 (GB, GCRC branch of the NCRR).