Amino Acid Supplements and Muscle Building in Older Adults
The Importance of Muscle Mass in Aging
As people age, they often experience a decline in muscle mass, known as sarcopenia. This condition can severely impact mobility and strength, affecting nearly half of individuals over the age of 80. The prevalence is even higher among those with additional health concerns or those recovering from fractures or surgeries. Enhancing muscle mass in these populations could lead to improved health outcomes and a reduced risk of falls and other complications.
Role of Amino Acids in Muscle Development
Amino acids serve as the fundamental building blocks of muscle proteins. While the body can synthesize many amino acids, there are essential amino acids that must be acquired through diet. These essential amino acids, particularly leucine, are crucial for individuals who may be undernourished.
Investigating the Effectiveness of Amino Acid Supplements
Research Overview
Numerous clinical studies have explored the effectiveness of amino acid supplements for muscle building, yielding mixed results. A recent report published in the British Journal of Nutrition aimed to consolidate findings from various studies to assess whether amino acid supplementation benefits older adults facing illness or frailty.
Study Selection and Methodology
The researchers conducted a comprehensive search of medical research databases to locate randomized controlled trials involving participants aged 60 and older, diagnosed with conditions such as frailty, malnutrition, or sarcopenia. They focused on studies that assessed the impact of amino acid supplementation on muscle mass, strength, or overall physical function. This meta-analysis approach aims to identify trends and effects that might not be apparent in individual studies, while also considering the reliability of the data based on participant numbers.
Findings from the Meta-Analysis
Inclusion of Studies
The analysis included 39 studies with a total of 4,274 participants, ranging in age from 60 to 103, and lasting from two weeks to two years. Of these, 31 studies provided participants with protein-rich foods or oral nutritional supplements, while eight studies specifically focused on essential amino acid supplementation.
Effects on Muscle Mass and Strength
Out of the studies, 16 evaluated the impact of amino acid supplements on muscle mass, revealing a statistically significant increase in muscle mass, although the effect size was modest. Additionally, 28 studies assessed muscle strength, primarily through handgrip and leg quadriceps strength tests. Results indicated a small positive influence on muscle strength, particularly among undernourished participants. Essential amino acids demonstrated greater effectiveness than other protein sources.
Impact on Physical Function
Thirty-four studies examined various aspects of physical function, such as walking speed, and found that amino acid supplements generally improved physical performance, though the effect was again small. The most notable benefits were observed in undernourished elderly individuals.
Quality Assessment of Included Studies
Evaluating Study Reliability
The researchers assessed the quality of the identified studies, noting that studies with a placebo-controlled, double-blind design tend to be more reliable. Despite these criteria, only seven of the 39 studies were classified as high quality. Notably, none of these high-quality studies demonstrated significant benefits from amino acid supplementation.
Conclusions and Future Directions
Overall Implications
The researchers acknowledged several limitations, including the exclusion of non-English studies and the focus solely on participants aged 60 and above. Consequently, it is possible that relevant studies were missed. Their findings suggest that while amino acid supplements may offer some benefits to older adults, particularly those who are undernourished, the overall effects are relatively small. Furthermore, the majority of studies reviewed had low quality, raising concerns about potential biases.
To enhance the understanding of amino acid supplementation in older adults, there is an urgent need for higher-quality clinical trials.
Reference
Cheng, H., Kong, J., Underwood, C., Petocz, P., Hirani, V., Dawson, B. & O’Leary, F. Systematic review and meta-analysis of the effect of protein and amino acid supplements in older adults with acute or chronic conditions. British Journal of Nutrition 119, 527-542 (2018).