Classification and definition of protein-calorie malnutrition.

The Eighth Joint Expert Committee on Nutrition of FAO and WHO1 emphasized the need for an accepted classification and definition of protein-calorie malnutrition. There are two pressing reasons for this. Bengoa' summarzed the available information about the frequency of protein-calorie malnutrition in different countries. There are many gaps, partly because for some countries there are no data, and partly because data which do exist are not always comparable. It is important that studies of prevalence should be extended and that the same criteria should be used everywhere. Secondly, the prevailing pattern of malnutrition in any region may give some information about the nature of the dietary deficiency and so will have a bearing on the preventive measures which are most appropriate. There are two schools of thought about this. According to what might now be called the classical theory, kwashiorkor results from a deficiency of protein with a relatively adequate energy supply, whereas marasmus is caused by an overall deficiency of energy and protein. From this it follows that where the kwashiorkor syndrome prevails, protein-rich supplements would be an appropriate method of prevention. On the other hand, Gopalan and his co-workers' produced evidence that there are no quantitative or qualitative differences in the diets of children who subsequently develop kwashiorkor or marasmus. They therefore proposed that the difference in the clinical picture reflects not a difference in diet but a difference in the capacity of the child to adapt. Whichever of these theories is correct the fact remains that according to reports in the literature the prevailing pattern does differ from one country to another.' If the differences are real there must be some reason for them, and the first step in finding the reason is to put the observations on a firm foundation with an agreed system of classification. The need for this is urgent because an alteration in the pattern of protein-calorie malnutrition and in its age of onset has important implications for the planning of preventive policies. General Problems of Classification The purpose of a classification is to be useful, and different classifications may be needed in different situations. With protein-calorie malnutrition a qualitative classification is needed to distinguish patterns of severe malnutrition in children admitted to hospital, whereas a quantitative classification is needed in community studies of prevalence and severity. Secondly, classification of malnutrition must inevitably be arbitrary, and can therefore be determined only by agreement. …