Sarcopenia is an age-related poor healthy outcome. nutrition intervention is one , progressive, generalized loss of muscle mass and the decrement in physical activity. Sarcopenia is associated with subsequent health hazards such as disability, falls, functional degeneration, hospitalization and death. There are similar causes between sarcopenia and constipation such as aging, reduced mobility, changes in diet and co-morbidities. Nutrition plays an important role for muscle maintenance. The trial tries to figure out the effect of enriched branched-chain amino acid (BCAA) nutrient on muscle mass, strength and physical performance of sarcopenia in the middle-aged and old people.

Sarcopenia is the progressive loss of skeletal muscle that comes with aging. The population in the World Health Organization (WHO) is ageing rapidly and the proportion of people aged 65 and older will get forecast to increase 25% in 2050. In aging society, sarcopenia has been valued in countries all over the world. The appearance of sarcopenia is associated with decreased physical function, falls, fractures, disability, hospitalization, and poor quality of life. Constipation is a common healthy problem. Similar mechanism and risk factors between sarcopenia and constipation are observed with the association of nutrition, but the interrelationships between them is rarely studied.

Prevention and treatment of sarcopenia is more and more important in the health care. Exercise has positive effects in muscle mass and strength but frail elder can't perform exactly. In addition, dietary intervention is one of the major key to reduce the rate of muscle mass loss and maintain physical performance and function.

Recent studies have found that daily and/or supplemental protein is effective prevention of sarcopenia. Protein is composed of amino acids that can induce a muscle protein anabolic response conditioned by the availability of branched-chain amino acids (such as leucine, isoleucine, valine). Delayed amino acid absorption and anabolic resistance are frequently noted among elderly. Branched chain amino acid (BCAA) or leucine supplementation stimulates muscle protein synthesis.

The recommendation about nutrition for preventing sarcopenia was still inconsistent. The time of study for muscle parameter improvement varies from three days to seven days. At present, there is no consensus about the optimal type of nutritional supplements and hint of how long does nutrition take.

The aim of the present study is to evaluate the influence of enriched BCAA on those people with pre-sarcopenia or sarcopenia. The hypothesis is that subjects after enriched-BCAA supplement improves their physical function, muscle strength, and muscle mass. Subsequently, when dis-continued enriched-BCAA muscle-related outcomes would decline.

Inclusion Criteria:

• over 40 years of age
• generally healthy according to responses to a standard health-screening questionnaire.

Exclusion Criteria:

• uncontrolled hypertension or diabetes
• stroke
• severe liver or renal disease
• gastrointestinal disease
• neuromuscular disease
• infectious disease
• cancer,
• pulmonary disease
• disease of the endocrine system
• history of seizures, neurological or significant psychiatric illness
• sensitivity to study ingredients.