ABSTRACT
Health is a state of complete physical, mental and social well-being and not merely the absence of disease or in rmity.
World Health Organization
Illness may be considered a programmed host response to infection and injury that is intended to aid recovery in the long term. However, illness can also lead to a set of “sickness behaviors” that include lethargy, sleepiness, loss of appetite (anorexia), reduced grooming, low regard for personal hygiene, and a state of mild depression. It is thought that sickness behavior is linked with increased levels of cytokines produced in response to invading microbes, injury, or chronic diseases stress.* The short-term host response to illness is powered ultimately by muscle loss. Chapter 1 provides an overview of the relations between nutrition, illness, and weight loss (Section 1.1). The important features of the host response to illness and injury are described in Section 1.2. In Section 1.3, we compare weight loss due to cachexia or anorexia with the effects of calorie restriction. In principle, there are many ways to improve well-being because illness is usually multidimensional. Possible modalities for improving health using bioactive peptide are outlined in Section 1.4. Overall, bioactive peptides and proteins present diverse opportunities for moderating the host response to illness thereby improving nutrition and health. The avoidance of weight loss during illness is an interesting surrogate measure of well-being that might be applied to evaluate bioactive peptides.
