The nature of nutritional deficiency in relation to growth failure and poverty.

A new classification of essential nutrients is proposed based on whether the major response to a deficiency is either (a) specific defects which lead to loss of particular functions and characteristic clinical signs and symptoms or (b) a primary cessation of growth. Diagnosis of deficiency of the nutrients which give rise to growth failure (nitrogen, essential amino acids, potassium, sodium, phosphorus, sulphur, zinc, magnesium) is particularly difficult because of the nature of the response and the lack of a body store. The implications of the differences in the types of deficiency are explored in relation to assessment of the likelihood that widespread deficiency exists. Poverty is particularly likely to be associated with unrecognised deficiency of these "growth" nutrients because of the monotony of the diet. This will lead to slow growth. There is probably a difference in the nutrient requirements for longitudinal and ponderal growth. Of the growth nutrients sulphur is likely to be required in much higher amounts for skeletal growth than soft tissue growth.