Known related effects of nutrition on aging muscle function.

Nutritional surveys in elderly populations have pointed to low energy and nutrient intake. This is of particular concern among the homebound or frail population groups [1–5] as reflected by considerable involuntary weight loss, including net protein loss [6, 7] leading to muscle wasting [8]. Inadequate intake of a number of nutrients has been associated with decreased body strength, lower resistance to infection and poorer indicators of quality of life [9–11]. Both an inadequate body weight for height and weight loss are associated with hip fractures, reduced autonomy, early institutionalization and increased mortality rates [12–21]. Low muscle mass was shown to be a significant independent risk factor for falls in elderly women after adjustment for age, balance and gait, medications, physical activity, proportion of body fat, and health status [22]. Preservation of muscle function is paramount for the maintenance of autonomy until advanced age. Since age-related decreases in functional ability are neither inevitable nor uniform [23], efforts have been made to identify factors associated with muscle function or functional status in general in many studies over the last decade. Two candidates for modifiable determinants, nutrition and physical activity, have been consistently studied in the context of observational and experimental designs. This chapter will focus on the manner in which nutritional status contributes to the preservation or deterioration of muscle function in the elderly. For this purpose, an epidemiological perspective rather than a mechanistic one will be adopted. Results from cross-sectional and longitudinal observations as well as from experimental studies will be presented and