Approximately 40% of body weight is made up of muscles and
thus quantitatively it is a critical organ that should not be ignored.
In addition to structural function in movement and maintenance of
posture and balance, skeletal muscle also contributes to metabolic
functions of the body. The muscle constitutes the main reservoir of
proteins and amino acids and in particular glutamine is synthesized
and stored in the muscle in large amounts. It also participates in
the regulation of glucose levels. Muscle loss occurs naturally with
aging, although the rate of decline can vary depending on the peak
attained in early life. Beyond ageing, muscle decline is associated
with many pathological states and chronic diseases, including
malnutrition-this is further accelerated by hospital immobilization
and bed rest. Most of these pathological conditions are associated
with different degrees of chronic inflammation, which plays a
critical role in the onset of muscle atrophy and malnutrition. Loss of
muscle is strongly linked to decline physical function, lower quality
of life and higher mortality. Nutrition intervention is vital to help
preserve and rebuild muscle. In recent years, an active metabolite
of the essential amino acid leucine, β-hydroxy-β-methyl-butyrate
(HMB), has attracted interest, with reported anabolic and anticatabolic
effects on muscle. Scientific research has been focused
on the use of HMB to maintain or rebuild muscle mass in older
populations, especially those at risk of sarcopenia. The impact of
early nutritional therapy on muscle mass and physical function
have been assessed in hospitalized and community-dweller older
subjects. In particular, the benefits of a protein-enriched oral
nutritional supplement (ONS) with HMB have been extensively
demonstrated. Evidence indicates that the use of such ONS can
lead to better nutritional status, as well as improved clinical and
functional outcomes in patients.