Nutrition and Metabolism
In this chapter we will study
procedures used for nutritional assessment of a patient;
methods of nutritional support;
varieties, pathology, and treatment of malnutrition;
two common eating disorders—anorexia nervosa and bulimia nervosa; and
fad diets and how to recognize suspicious dietary advice.
Clinical Approaches to Nutrition
Understanding and appreciating nutrition has become
increasingly important in our everyday lives. We are
constantly bombarded with advertisements and books
promising rapid and safe weight loss. On the other
hand, prolonged illnesses and certain medical
procedures can induce
a lack of one or
more nutrients due to dietary deficiency or the
inability to properly absorb nutrients. Inherited
phenylketonuria and cystic fibrosis, require specific
diets for proper management.
In developing countries
or other areas with limited economic means, states of
malnutrition such as
relatively common. And just as a lack of certain
vitamins and minerals can cause disease, too much of
a certain substance, as in hypervitaminosis, can also
have harmful effects.
Interactions between nutrients and drugs are
common. Malnutrition can impair drug absorption or
metabolism, leading to potentially hazardous side
effects. Drugs may also alter appetite or interfere with
the metabolism of specific macromolecules, leading to
energy and nutrient imbalances. Finally, drugs may
hinder the absorption of vitamins and minerals.
Assessing Nutritional Status
A nutritional assessment determines a patient’s health
from a nutritional perspective. An abbreviated
assessment can be conducted by a clinician, while a
complete assessment is most often performed by either
a dietitian or a clinician who has advanced training in
nutrition. Either type employs many of the same
procedures involved in obtaining a patient history and
conducting a physical examination.
A complete nutritional assessment consists of the
patient’s history, body measurements, a physical
examination, and laboratory tests (if warranted). The
patient history provides information about the risk
factors for poor nutrition, which can be divided into
four broad categories:
identifies specific diseases that
predispose a patient to poor nutrition, such as
AIDS, cancer, diabetes mellitus, lung disease, or
physiological conditions such as obesity, low
body weight, or anorexia.
indicates whether the
patient is at risk for nutritional deficiency.
factors as having no one to eat with, little money
for food, inadequate food storage or preparation
facilities, minimal education, poor self-esteem,
and lack of transportation all predispose a patient
to nutritional deficit.