There are physical, mental, social and environmental changes which tak
e place with ageing; for example, decreased physical activity, increas
e in body fat, decrease in lean body mass and consequently decreased e
nergy intake may be associated with physiological functions that affec
t metabolism, nutrient intake, physical activity and risk of disease.
There are now many studies which have found that undernutrition is pre
valent and often unrecognized in patients admitted to hospitals and in
stitutions. There is also evidence which Links protein-energy undernut
rition or its markers with clinical outcomes in acute and non-acute ho
spital settings and that nutritional supplements can improve outcomes
in some of these settings. However, most clinically-available nutritio
n screening instruments lack sensitivity and specificity, and abnormal
nutritional indicators may simply reflect effects of age, functional
disability, or severe underlying disease. Thus, causal relationship ca
nnot be assumed without a sufficiently powerful intervention study whi
ch adequately adjusts for the effects of non-nutritional factors, such
as the number and severity of co-morbid conditions on clinical outcom
e.