The World Health Organization defines nutrition as "a process whereby living organisms utilize food for maintenance of life, growth and normal function of organs and tissues and the production of energy". Malnutrition results when this process goes wrong, whether because of problems on the intake side or because of problems in processing the intake.

The most important nutrition deficiency disease is protein-energy malnutrition, which is important because of its high mortality rate, its wide prevalence, and the irreversible physical and sometimes mental damage it may cause. In addition, there are three major types of diseases resulting from micronutrient deficiencies. These are:

• xerophthalmia, which is important because of its contribution to the mortality of malnourished children, its wide prevalence, and the permanent blindness it causes;

• nutritional anemias, which are important because of their wide distribution, their contribution to mortality from many other conditions, and their effects on working capacity; and

• endemic goiter, because of its wide distribution.

Xerophthalmia results primarily from vitamin A deficiency, anemia from iron deficiency, and goiter from iodine deficiency.

The most widespread form of malnutrition is protein-energy malnutrition (PEM), sometimes described as protein-calorie malnutrition (PCM). It is so prevalent that in the absence of other specifications, references to malnutrition are understood to indicate PEM. Kwashiorkor and marasmus are intense forms of PEM. At times the term undernutrition is used to designate PEM.

PEM is usually due to a lack of energy foods rather than to a lack of protein intake. The symptoms of protein deficit often observed in cases of severe malnutrition result from the fact that the protein that is obtained is diverted to fulfilling immediate energy needs, and thus is not available for the body building and maintenance functions normally fulfilled by protein. If energy supplies are adequate, the protein remains available for its body building and maintenance functions, a phenomenon described as protein sparing.

The United Nations Administrative Committee on Coordination has a Sub-Committee on Coordination (ACC/SCN) that is responsible for coordinating nutrition-related activities among the UN agencies. In its draft of Ending Malnutrition by 2020 (1999) the SCN summarized the global dimensions of nutrition problems as follows:

Major Nutritional Challenges

• Over 200 million children are underweight for their age.

• Stunting dominates malnutrition and is linked to mental impairment: current UN goals leave a billion children growing up by 2020 with impaired development. Malnutrition is the tip of the iceberg: suboptimal growth will have affected many more, by 2020 at least a further 1 billion children will have suffered from stunted growth on a cumulative basis.

• Stunting occurs especially in infants born with low birthweight from malnourished mothers. Low birthweight, its causes and remedies, has been neglected.

• About 1 billion adults in developing countries are underweight (i.e. with a body mass index of less than 18.5). This type of adult malnutrition impairs work capacity and lowers resistance to infection. Maternal malnutrition increases the risk to future generations.

• Infantile anaemia causes poor brain development; also exacerbated by maternal malnutrition.

• Maternal anaemia is pandemic - over 80% in some countries with scandalously high rates of maternal deaths. Rates are also high in schoolchildren and adolescents.

• Evidence suggests a fundamental link between maternal and childhood malnutrition and a subsequent increased susceptibility in adult life to abdominal obesity, diabetes, heart disease and high blood pressure.

• These diet-related non-communicable chronic adult diseases - including cancers - already present a major public health challenge particularly in developing countries. By 1990, coronary heart disease had become the leading cause of death world-wide and over 60% of the 15 million deaths attributed to diseases of the circulatory system were in the developing world.

   (ACC/SCN, 1999)

In addition, the ACC/SCN noted that obesity affects about 250 million people.

Continue to II-b. Causes of Malnutrition

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Subsection II-a last updated on September 25, 1999