Elsevier

Nutrition

Volume 20, Issue 5, May 2004, Pages 445-451
Nutrition

Applied nutritional investigation
Effect of β-hydroxy-β-methylbutyrate, arginine, and lysine supplementation on strength, functionality, body composition, and protein metabolism in elderly women

https://doi.org/10.1016/j.nut.2004.01.009Get rights and content

Abstract

Objective

With advancing age, there is a gradual loss of muscle mass, strength, and functionality. The current studies were conducted to determine whether a mixture of specific nutrients, arginine and lysine, which support protein synthesis, and β-hydroxy-β-methylbutyrate (HMB), which can slow protein breakdown, could blunt the gradual loss of muscle that occurs in the elderly, thus improving strength and functionality.

Methods

In double-blind studies conducted at two separate sites, women (mean 76.7 y) were randomized to a placebo group (n = 23) or an experimental treatment group (2 g β-hydroxy-β-methylbutyrate, 5 g arginine, and 1.5 g lysine daily; n = 27).

Results

After 12 wk, there was a 17% improvement in the “get-up-and-go” functionality test in the experimental group (−2.3 ± 0.5 s) but no change in the placebo group (0.0 ± 0.5 s; P = 0.002). The improvement in functionality also was reflected by increased limb circumference, leg strength, and handgrip strength (all P < 0.05) and positive trends in fat-free mass (P = 0.08). Whole-body protein synthesis, estimated with the 15N-glycine tracer technique over a 24-h free-living period, increased approximately 20% in the experimental treatment group as opposed to the placebo group (P = 0.03).

Conclusion

These studies indicated that daily supplementation of β-hydroxy-β-methylbutyrate, arginine, and lysine for 12 wk positively alters measurements of functionality, strength, fat-free mass, and protein synthesis, suggesting that the strategy of targeted nutrition has the ability to affect muscle health in elderly women.

Introduction

Beginning at approximately age 40 y, muscle mass in humans atrophies at a rate of approximately 8% per decade1, 2, 3, 4 until age 70 y, when this loss increases to 15% per decade.3 The underlying cause of this loss is multifactorial and appears to involve motor unit remodeling,5 possibly age-related disease effects,6 and a decrease in hormonal activity,7 all of which can contribute to the decrease in the rate of protein synthesis observed with age.8, 9, 10 It is estimated that the rate of protein synthesis in humans decreases by as much as 38% by middle age (50 y) and by 55% with advanced age (70+ y) when compared with younger individuals (∼20 y).10

Several strategies have been proposed to stem age-associated muscle loss, such as exercise, complete nutrition intervention, and hormone therapy. However, only resistance training has been proven effective.11, 12, 13 Unfortunately, exercise training is adopted only by a very small percentage of elderly individuals. Although relatively easy to implement, complete nutritional intervention has not always been effective,13, 14, 15, 16 and hormonal therapy poses significant potential side effects without consistent effects on muscle.17

One strategy with potential is to use targeted nutritional supplementation that stimulates the process of protein synthesis over that of protein breakdown. For example, a recent study has shown that supplementation of essential amino acids increases muscle protein anabolism in the elderly.18 Other studies have successfully implemented such a strategy to minimize muscle loss related to acquired immunodeficiency syndrome19 and cancer-related cachexia20 by supplementing an amino acid mixture of arginine (ARG) and glutamine to support protein synthesis in addition to the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) to blunt the rate of protein breakdown. In both diseases, muscle wasting was reversed over an 8-wk period by daily supplementation of this mixture.

The objective of the current studies was to determine whether a once-daily dosage of HMB, ARG, and lysine (LYS) could improve the age-associated changes in muscle mass, functionality, and protein metabolism in elderly women. LYS was used in this nutrient mixture because it is one of the only true essential amino acids,21 and data have shown that supplementation of essential amino acids in the elderly may stimulate muscle protein anabolism.18 In addition, recent studies have demonstrated that the requirement for LYS is much higher than generally accepted22, 23; thus, supplemental LYS may help meet this requirement in the diet of the elderly person. ARG was used because it has been shown to stimulate whole-body protein synthesis.24, 25 HMB was included in the mixture because it has been shown to prevent excessive muscle proteolysis during metabolic stress26, 27, 28 and has recently been shown to enhance muscle mass gains in exercising older men and women.29

Section snippets

Subjects

Twenty-nine women in study 1 (65 to 90 y) and 28 women in study 2 (62 to 85 y) were recruited from senior citizen centers and adult assisted-living and care facilities. One week before the initiation of the study, each subject filled out a questionnaire detailing her medical history. Subjects were excluded if they were receiving active treatment for liver or kidney disease. They also were excluded for uncontrolled hypertension or uncontrolled diabetes. All subjects gave written informed consent

Subjects

Table I summarizes the data for body weight, composition, and strength measures. In study 1, 10 subjects (81.1 ± 1.8 y) assigned to the placebo supplement and 13 subjects (84.2 ± 1.6 y) assigned to the HMB/ARG/LYS supplement completed the 12-wk study. Four of the 14 placebo-supplemented subjects (29%) withdrew from the study. Two withdrew because of flu symptoms, one dropped out because of a pre-existing medical condition, and the fourth subject died of an unrelated cardiovascular accident. Two

Discussion

The current study demonstrated that using a nutritional supplement containing HMB, ARG, and LYS results in increased fat-free mass, increased limb circumferences, enhanced strength, and improved functionality in elderly women. Previous attempts to increase muscle mass in the elderly without exercise use various hormonal treatments. Administrations of growth hormone, insulin-like growth factor, and testosterone have significant potential side effects that are of concern, and each has been tested

Summary

Daily supplementation of HMB, ARG, and LYS for 12 wk positively altered measurements of functionality, strength, fat-free mass, and protein synthesis, suggesting that the strategy of targeted nutrition has the ability to affect muscle health in elderly women.

Acknowledgements

The authors thank Dr. John Rathmacher for his contribution in acquisition of data, Dr. Naji Abumrad for his critical review of the manuscript, Metabolic Technologies, Inc. for supplying the supplements, and the volunteers for their faithful participation in this study. They also thank the nursing staffs of the General Clinical Research Center (GCRC, RR-00095) at Vanderbilt University and Meg Speer and the staff of Eastern Star Masonic Home, Boone, Iowa. They appreciate the excellent technical

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  • Cited by (0)

    The study was supported in part by a gift from Metabolic Technologies, Inc., Ames, Iowa and the Clinical Nutrition Research Unit (DK-26657) and the General Clinical Research Center (RR-00095) at Vanderbilt University.

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