Nestle Supplement 2

NUTRITION AND THE OLDER PERSON TABLE 1. Causes of weight loss in older persons Voluntary Food restriction Increased exercise Involuntary Starvation Cachexia/anorexia Sarcopenia TABLE 2. Potential causes of age-related loss of muscle mass Sedentary lifestyle Reduced levels of and responsiveness to trophic hormones growth hormone androgens (testosterone) insulin-like growth factor 1 dehydroepiandrosterone sulfate (DHEAS) estrogens (estrone, estradiol) 25-hydroxy ergocalciferol (vitamin D) Decrease or imbalance in protein metabolism Neurodegenerative process Muscle fiber atrophy Increased prevalence of disability Decreased functional capacity Decreased basal metabolic rate Alteration in gene expression produces a decline in function. Up to 65% of older men and women report that they cannot lift 10 pounds using their arms.29 Although sarcopenia is due to a reduction in skeletal muscle mass, not all subjects demonstrate a loss in body weight. An increase in fat mass accompanying aging may mask the loss of non-fat mass, resulting in normal or even an obese body weight in sarcopenic persons. Anorexia. Appetite regulation (and, therefore, food intake) is affected by illness, drugs, dementia, or mood disorders.7,30,31 Anorexia may be a physiological response to aging, resulting from changes in the physiological regulation of appetite and satiety.32 The relationship between hedonic qualities of food, gastrointestinal and central satiation drives, and hormonal relationships may explain this observed difference.33 Acute illness is characterized by a spontaneous decrease in food intake despite an increased need for energy and nutrients.34 Although seemingly paradoxical, the voluntary suppression of food intake during illness is common to most species.35 A reduction in food intake accompanying acute illness occurs both before and during hospitalization. In a prospective study of elderly people, 65% of men and 69% of women had an insufficient energy intake in the month before hospitalization.36 This reduction in nutrient and energy intake beginning with acute illness predisposes to a risk for worsening undernutrition during hospitalization. The importance of understanding this relationship lies in the hope that pharmacological37 or dietary interventions38 may reverse this anorexia of aging. CAUSES OF INVOLUNTARY WEIGHT LOSS Loss of body weight in older persons can result from voluntary or involuntary causes (Table 1). Involuntary weight loss may result from several conditions, including ingestion of inadequate calories (starvation), weight loss due to disuse atrophy or hormonal deficiencies (sarcopenia), a decrease in appetite (anorexia) or the effects of disease (cachexia), and a combination of these factors.18 Starvation. Starvation results in a loss of body fat and non-fat mass due to inadequate intake of protein and energy. Starvation is a pure protein-energy deficiency, thus forcing a reduction in both fat and fat-free mass.The key physiological sign of starvation is that it is reversed by the replenishment of nutrients.19 Sarcopenia. Unintended weight loss in older persons may result from a loss in fat-free mass. The age-related decline in muscle mass observed in normal aging has been termed sarcopenia. The fact that muscle mass decreases with age has been known for some time. Earlier work demonstrated that the excretion of urinary creatinine, a measure of muscle creatine content and total muscle mass, decreases by nearly 50% between the ages of 20 and 90 years.20 This age-related loss of muscle mass appears to be fairly consistent, at a rate of approximately 1%–2% per year past the age of 50 years.21 This decline in muscle mass occurs in both sedentary and active aging adults (Table 2). In contrast, in healthy young adults, no net change occurs in skeletal muscle mass under equilibrium conditions due to balance in skeletal muscle protein synthesis and degradation.This age-related reduction in muscle mass and strength is also accompanied by a reduction in motor unit number22 and by atrophy of muscle fibers, especially the type IIa fibers.23 An associated decline in protein synthesis, particularly in the synthesis of myosin heavy chains, has been observed.24 The loss of muscle mass with aging is clinically important because it leads to diminished strength and exercise capacity.25 Dynamic, static, and isokinetic muscle strength decreases with age.26 Maximal oxygen consumption declines with age27 at a rate of 3%–8% per decade beginning at age 30. However, after correction for muscle mass, there is no important decline in VO2Max with aging, indicating that a change in muscle mass is the significant factor.28 The result of age-related muscle mass loss 4 • DECEMBER 2007

Table of Contents Feed for the Digital Edition of Nestle Supplement 2

Nestle Supplement Table of Contents Introduction to Weight Loss in Older Persons Diagnosis and Management of Oropharyngeal Dysphagia in the Elderly The Danger of Weight Loss in the Elderly Nutrients and Frailty

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