Clinical Effectiveness of Protein and Amino Acid Supplementation on Building Muscle Mass in Elderly People: A Meta-Analysis
Yang Y-m (2014) Clinical Effectiveness of Protein and Amino Acid Supplementation on Building Muscle Mass in Elderly
People: A Meta-Analysis. PLoS ONE 9(9): e109141. doi:10.1371/journal.pone.0109141
Clinical Effectiveness of Protein and Amino Acid Supplementation on Building Muscle Mass in Elderly People: A Meta-Analysis
Zhe-rong Xu 0
Zhong-ju Tan 0
Qin Zhang 0
Qi-feng Gui 0
Yun-mei Yang 0
Conrad P. Earnest, Texas A&M University, United States of America
0 1 Department of Geriatrics, First Affiliated Hospital, School of Medicine, Zhejiang University , Hangzhou , China , 2 State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Department of Geriatrics, First Affiliated Hospital, School of Medicine, Zhejiang University , Hangzhou , China
Objective: A major reason for the loss of mobility in elderly people is the gradual loss of lean body mass known as sarcopenia. Sarcopenia is associated with a lower quality of life and higher healthcare costs. The benefit of strategies that include nutritional intervention, timing of intervention, and physical exercise to improve muscle loss unclear as finding from studies investigating this issue have been inconsistent. We have performed a systematic review and meta-analysis to assess the ability of protein or amino acid supplementation to augment lean body mass or strength of leg muscles in elderly patients. Methods: Nine studies met the inclusion criteria of being a prospective comparative study or randomized controlled trial (RCT) that compared the efficacy of an amino acid or protein supplement intervention with that of a placebo in elderly people ($65 years) for the improvement of lean body mass (LBM), leg muscle strength or reduction associated with sarcopenia. Results: The overall difference in mean change from baseline to the end of study in LBM between the treatment and placebo groups was 0.34 kg which was not significant (P = 0.386). The overall differences in mean change from baseline in double leg press and leg extension were 2.14 kg (P = 0.748) and 2.28 kg (P = 0.265), respectively, between the treatment group and the placebo group. Conclusions: These results indicate that amino acid/protein supplements did not increase lean body mass gain and muscle strength significantly more than placebo in a diverse elderly population.
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Sarcopenia is an age related loss of muscle mass and strength,
and is associated with a lower quality of life resulting from a
reduced ability to perform daily living tasks [1]. Sarcopenia results
in increased healthcare costs of approximately $900 per elderly
adult which in the USA is approximately $18.5 billion per year
[2]. Prevalence of sarcopenia differs by gender, living
circumstances, and continent: 13.2% of Chinese men and 4.8% of
Chinese women who are $70 years of age have sarcopenia, while
4570% and 717.5% of American men and 2%59% and 4
10% of American women have sarcopenia, respectively [3].
Agerelated muscle loss is highly prevalent in nursing homes, with rates
being as high as 68% in elderly men and 21% in elderly females
[4], whereas community dwelling elderly have lower prevalence
rates in males (10%) but higher rates in women (33%) [5].
Inadequate nutrition, oxidative stress, low physical activity
levels, inflammation, and reduced hormone concentrations
contribute to age related muscle loss [6]. Possible strategies that
reliably increase muscle mass and strength in the elderly have been
actively investigated, but conclusions on the benefits of different
nutritional interventions, timing of administration, and physical
exercise from studies have been conflicting [720].
Several nutritional interventions such as creatine monohydrate,
whey protein, caseinate, and essential amino acids appear to
augment protein synthesis in muscles [1,21,22]. Numerous studies
have found that these nutritional supplements enhance the
magnitude of gain in lean body mass and muscle strength in
older adults undergoing exercise training [1,6,15]. Essential amino
acid and leucine supplementation have increased protein synthesis
in muscles and are thought to be better strategies for offsetting
muscle loss than intact protein [7,16,2224], due in part to their
higher absorption [22]. However, several studies that compared
the effect of whey protein or amino acid supplementation on
skeletal muscle mass, lean body mass, or strength in healthy elderly
to that of placebos have not detected a significant difference
between the two groups [8,17].
Many of the studies evaluating the impact of protein or amino
acid supplementation on sarcopenia have been small and
evaluated different supplements. In order to maximize the
biostatical power of placebo controlled clinical trials, we have
performed a meta-analysis to assess the ability of protein or amino
acid supplementation to augment lean body mass or strength of leg
muscles in elderly patients.
Experimental Methods
PubMed, Google Scholar, The Cochrane Library, EMBASE,
and ClinicalTrials. (...truncated)