Cicely Williams, in her original description of
kwashiorkor, implied that deficiency of
protein in the baby's food could be a main cause of the syndrome. The hallmark of
kwashiorkor is oedema. According to the 'classical' theory, an inadequate intake of
protein leads to a low
plasma albumin concentration, which in turn causes oedema. This theory has been contested from several points of view: that hypoalbuminaemia is not the major factor determining the presence of oedema, and that there is no real evidence of
dietary protein deficiency. The resolution of this question is of some importance from the point of view of public health diagnosis and prevention. A crucial point in the argument is the pathogenesis of oedema, which is discussed in some detail. Although it is clearly multifactorial, with
electrolyte disturbances--
potassium deficiency and
sodium retention--playing an important role, it is contended that the classical theory is essentially correct. On the dietary side, recent experimental work supports the earlier view that the development of oedema depends on a relative deficiency of
protein with a relative excess of energy. Comparisons of intakes with requirements are unconvincing in view of uncertainty about the validity of the estimates of children's needs for
protein.