An Overview of Sarcopenia: Focusing on Nutritional Treatment Approaches

Abstract

Sarcopenia is a syndrome characterized by the progressive and generalized loss of skeletal muscle mass and strength. This condition is associated with physical disability, decreased quality of life, and increased mortality. Therefore, reducing the prevalence of sarcopenia could significantly lower healthcare costs. Sarcopenia can be classified into primary and secondary sarcopenia. The former is related to aging and begins after the fourth decade of life; after that, there is a muscle loss of around 8% per decade until age 70 years, which subsequently increases to 15% per decade. On the other hand, secondary sarcopenia can affect all individuals and may result from various factors including physical inactivity, malnutrition, endocrine disorders, neurodegenerative diseases, inflammation, and cachexia. Understanding the multiple mechanisms involved in the onset and progression of sarcopenia allows for us to develop strategies that can prevent, treat, or at least mitigate muscle loss caused by increased protein breakdown. One potential treatment of sarcopenia is based on nutritional interventions, including adequate caloric and protein intake and specific nutrients that support muscle health. Such nutrients include natural food rich in whey protein and omega-3 fatty acids as well as nutritional supplements like branched-chain amino acids, β-hydroxy-β-methylbutyrate, and vitamin D along with food for special medical purposes. It is important to emphasize that physical exercises, especially resistance training, not only promote muscle protein synthesis on their own but also work synergistically with nutritional strategies to enhance their effectiveness.

Keywords: branched-chain amino acids; muscle mass; muscle strength; nutrients; omega-3 fatty acids; vitamin D; whey proteins; β-hydroxy-β-methylbutyrate.

Figure 1

The insulin-like growth factor 1 (IGF1)–Akt pathway that controls muscle growth via mammalian target of rapamycin (mTOR) and muscle degradation via FoxO. Reproduced with permission from Schiaffino et al. [25].

Figure 2

Time needed to complete the “Chair stand test” based on different types of physical activity and age groups. Reproduced with permission from Landi et al. [78].

Figure 3

Tumor-specific expression profiles of cachexia-inducing factors (CIFs) and their correlations with the prevalence of cachexia and weight loss. (A) Schematic representation of the expression pattern of 25 CIFs in different tumor types of The Cancer Genome Atlas (TCGA); (B,C) Pearson’s correlations coefficient (r) with corresponding p values for the covariation between the number of differentially expressed CIFs (y-axis) from TCGA data sets (tumor tissues vs. matched normal TCGA and GTEx data) and the percentage of weight loss (x-axis; (B)) or the percentage of cachexia prevalence (x-axis; (C)) for specific tumour types from relevant literature data. Reproduced with permission from Freire et al. [98].

Figure 4

The metabolism of beta-hydroxy-beta-methyl-butyrate. Reproduced with permission from Wilson et al. [149].