Nutritional Supplements with Oral Amino Acid Mixtures Increases Whole-Body Lean Mass and Insulin Sensitivity in Elderly Subjects with Sarcopenia

https://doi.org/10.1016/j.amjcard.2008.03.004Get rights and content

Decreases in whole-body lean mass can cause sarcopenia, a disease frequently found in the elderly. This condition is frequently associated with frailty and disability in aging as well as the onset and progression of several geriatric syndromes. Sarcopenia therefore must be managed with multidimensional approaches that include physical training, nutritional support, and metabolic and anabolic treatment. The purpose of our study was to assess the effect of an orally administered special mixture of amino acids (AAs) in elderly subjects with reduced lean body mass and sarcopenia. A randomized, open-label, crossover study was conducted in 41 elderly subjects (age range: 66–84 years) with sarcopenia, assigned to 2 distinct treatments (AAs and placebo). All subjects had normal body weight (body mass index within 19–23). The AA treatment consisted of 70.6 kcal/day (1 kcal = 4.2 kJ) of 8 g of essential AA snacks, given at 10:00 am and 5:00 pm. Lean mass was measured with dual-energy x-ray absorptiometry in leg, arm, and trunk tissues. Significant increases in whole-body lean mass in all areas were seen after 6 months and more consistently after 18 months of oral nutritional supplementation with AAs. Fasting blood glucose, serum insulin, and homeostatic model assessment of insulin resistance (an index of insulin resistance) significantly decreased during AA treatment. Furthermore, a significant reduction in serum tumor necrosis factor–α (TNF-α) and a significant increase in both insulin-like growth factor–1 (IGF-1) serum concentrations and in the IGF-1/TNF-α ratio were also found. No significant adverse effects were observed during AA treatment. These preliminary data indicate that nutritional supplements with the oral AA mixture significantly increased whole-body lean mass in elderly subjects with sarcopenia. The improvement in the amount of whole-body lean mass could be linked to increased insulin sensitivity and anabolic conditions related to IGF-1 availability.

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Subjects and experimental design

A randomized, open-label, crossover study of AAs versus placebo was designed and conducted in 41 consecutive elderly outpatients with overt sarcopenia and reduced whole-body lean mass. The diagnosis of sarcopenia was confirmed by clinical evaluations (physical and anthropometric) and by instrumental validation with dual energy x-ray absorptiometry (DEXA) (DPX-L Lunar; Radiation Corporation, Madison, WI) that demonstrated reduced lean mass in leg, arm, and trunk tissues. All subjects gave their

Results

A mild but significant increase in body weight was demonstrated at the end of the study (after 16 months) in both groups of elderly subjects with sarcopenia. In effect, the mean values of body mass index significantly increased in Group A from 20.9 ± 1.2 to 22.3 ± 1.7 (p <0.05), and in Group B from 20.6 ± 1.4 to 22.5 ± 1.9 (p <0.01); whereas the total body fat mass remained unchanged throughout the study (from 26.5% ± 3.6% to 26.9 ± 3.9 %). No changes in arterial blood pressure levels or heart

Discussion

Sarcopenia, the pathologic decrease in whole-body lean mass in the elderly, is characterized by increased frailty, polypathology, and disability related to hypocynetic conditions. This deleterious condition of aging carries high economic and social costs. Therefore, the correction of sarcopenia can be considered a primary outcome of geriatric rehabilitative procedures.

Our clinical investigation clearly demonstrated that long-term nutritional supplementation with a special mixture of oral AAs

Conclusion

Our study shows that nutritional supplementation with oral AA mixtures increases whole-body lean mass in elderly subjects with sarcopenia. More studies need to be performed, both along these lines and also to develop new perspectives about the nutritional approach to sarcopenia.

Author Disclosures

The authors who contributed to this article have disclosed the following industry relationships:

Sebastiano B. Solerte, MD, PhD, has no financial arrangement or affiliation with a corporate organization or a manufacturer of a product discussed in this article.

Carmine Gazzaruso, MD, has no financial arrangement or affiliation with a corporate organization or a manufacturer of a product discussed in this article.

Roberto Bonacasa, MD, has no financial arrangement or affiliation with a corporate

Acknowledgment

We thank medical writer Dr. Robert Coates (Centro Linguistico, Bocconi University, Milan, Italy) for his linguistic revision.

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    This work was supported in part by a grant from the University of Pavia, Pavia, Italy (project FAR, financial year 2005).

    Statement of author disclosure: Please see the Author Disclosures section at the end of this article.

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