Protein–energy malnutrition (PEM) is the current term for a group of nutritional diseases related to dietary protein and energy (calorie) intake. These diseases are most frequently seen in infants and young children in developing countries but may be a feature of famine or the result of illness for people of all ages throughout the world. Research during the twentieth century has considerably clarified the causes and manifestations of what are now known as dietary-related effects on the growing or mature individual. PEM includes conditions known in the medical world as kwashiorkor, marasmus, and growth retardation in children. Related to PEM are pellagra, starvation, and protein malnutrition. Infection, debilitating disease, and surgical procedures are frequently complicated by PEM. It is, therefore, a factor of importance in determining morbidity and mortality and has to be taken into account by health-care personnel at all levels.

Historical Concepts of Protein and Energy

Early reports of what may have been PEM lack the clinical, pathological, and biochemical details that make identification certain. The history of PEM is thus confined to the nineteenth and twentieth centuries, and it is only in the last 50 years that clarification of the various forms that PEM can manifest has emerged.

In his book Protein and Energy, Kenneth J. Carpenter has provided a detailed survey of nutritional science as it was known in the period from 1614 to 1893 (Carpenter 1994: 1–99). Of particular interest in relation to later discoveries is that the first “balance studies” were carried out by Italian scientist S. Santorio in 1614. He weighed his food and drink as well as his excreta (urine and feces) and measured changes in his own weight. There was an unexplained daily disappearance of 5 pounds of material that he attributed to a breakdown of body tissue that was then secreted through the skin as insensible perspiration; the losses were made good by the nourishment ingested. This was only a more quantitative restatement of Galen’s view in the second century that “[o]ur bodies are dissipated by the transpiration that takes place through the pores in our skins that are invisible to us; therefore we need food in a quantity proportionate to the quantity transpired” (Carpenter 1994: 1).