Chronic alcoholism. Alcoholic persons may sometimes suffer from malnutrition but are more frequently lacking in several vitamins, especially thiamine, pyridoxine, folate, and vitamin A, as a result of dietary deficiency, defective GI absorption, abnormal nutrient utilization and storage, increased metabolic needs, and an increased rate of loss. A failure to recognize thiamine deficiency in patients with chronic alcoholism may result in irreversible brain damage (e.g., Korsakoff psychosis, discussed in Chapter 23).
Acute and chronic illnesses. The basal metabolic rate becomes accelerated in many illnesses (in patients with extensive burns, it may double), resulting in increased daily requirements for all nutrients. Failure to recognize these nutritional needs may delay recovery. Malnutrition is often present in patients with advanced cancer and AIDS.
Self-imposed dietary restriction. Anorexia nervosa, bulimia, and less overt eating disorders affect a large population of persons who are concerned about body image or suffer from an unreasonable fear of cardiovascular disease (anorexia and bulimia are discussed in a separate section in this chapter).
• Other causes. Additional causes of malnutrition include GI diseases, acquired and inherited malabsorption syndromes, specific drug therapies (which block uptake or use of particular nutrients), and total parenteral nutrition.
The remainder of this section presents a general overview of nutritional disorders. Particular attention is devoted to severe acute malnutrition, anorexia nervosa and bulimia, deficiencies of vitamins and trace minerals, and obesity, with a brief consideration of the relationships of diet to atherosclerosis and cancer. Other nutrients and nutritional issues are discussed in the context of specific diseases throughout the text.
The World Health Organization defines severe acute malnutrition (SAM) as a state characterized by a greatly reduced weight for height ratio that is below 3 standard deviation of WHO standards. Worldwide about 16 million children under the age of 5 years are affected by it. It is common in poor countries, where as many as 25% of children may be affected and where it is a major contributor to the high death rates among the very young. In addition to loss of life, wars also exact a heavy toll on refugees who live in abject poverty. In camps set up for refugees from Syria, as many as 20% of the children are severely or moderately malnourished.
SAM previously called protein energy malnutrition (PEM) manifests as a range of clinical syndromes, all resulting from a dietary intake of protein and calories that is inadequate to meet the body’s needs. The two ends of the spectrum of SAM are known as marasmus and kwashiorkor. It should be noted that from a functional standpoint, there are two protein compartments in the body: the somatic compartment, represented by proteins in skeletal muscles, and the visceral compartment, represented by protein stores in the visceral organs, primarily the liver. These two compartments are regulated differently, as detailed subsequently. The somatic compartment is affected more severely in marasmus and the visceral compartment is depleted more severely in kwashiorkor. Clinical assessment of undernutrition is discussed next, followed by descriptions of marasmus and kwashiorkor.