Protein malnutrition is the result of many factors, including: a deficiency of calories in general as well as of dietary protein; the consequences of a high incidence of infectious diseases including intestinal parasitism; ignorance of the principles of good nutrition; and inadequate purchasing power especially when children are numerous and closely spaced. Early childhood, pregnancy and the nursing period constitute the vulnerable periods when nutritional needs in general and the requirements for protein in particular are greatest.
The impact of malnutrition on economic and social development is all-pervasive. In spite of the high rates of child mortality, fertility levels are so correspondingly high as to maintain a very rapid population growth. There is a general agreement that the persistence of high mortality among infants and children is a major obstacle to family planning, as parents will not reduce the numbers of their children deliberately without greater assurance of their survival to adulthood. (Reduction in malnutrition among infants and children thus emerges as a prerequisite for fertility reduction, without which the population explosion is assuming disastrous proportions). The direct and indirect costs of malnutrition to the economy are often far more than would be required for its prevention. To direct increase in expenditures for medical care must be added the costs to society of rearing children who do not survive to a productive age, who having survived are less responsive to education, or who become constitutionally deficient adults. There is also an economic loss from absenteeism and reduced working capacity. The combined effect is to retard economic as well as social development.
Protein malnutrition is more common in countries where there is a lack of adequate food supplies within a country or as the result of social, economic and cultural factors that limit the consumption of protein by vulnerable groups of the population, even when the total supplies are adequate for the population as a whole. This is why the average figures for protein intake expressed on a per capita basis do not reflect the frequently encountered gross inadequacy of protein in the diet of the vulnerable groups in the population. Moreover, a low intake of calories and frequent episodes of infection often lead to considerable wastage of even the small quantity of protein consumed and are major factors in the widespread protein-energy deficiency. During famine and other emergency situations, this problem becomes particularly serious.
Protein malnutrition is an important cause of infant and young child mortality, stunted physical growth, low work output, premature ageing and reduced life span in the developing world. Recent research has also revealed a link between malnutrition in infancy and early childhood, and impaired learning and behaviour in later life. The widespread occurrence of protein malnutrition especially among infants, pre-school children, and expectant and nursing mothers in many developing nations spells grave danger to the full expression of the genetic potential of the population of large sections of the world community.