Human Protein Deficiency: Results of a Nigerian Village Study

Abstract

A skimmed milk supplement was fed to lactating women to raise the protein content of their energy adequate diet from 25 or 50 grams to 100 g/day. The amount of milk secreted, as well as the amount consumed by the child, increased significantly. The children gained more weight. There was no change in concentration of total milk solids, protein or lactose in the majority of cases. Hence, the principal effect of protein deficiency on milk secretion was a decrease in volume. Skimmed milk protein also fed as a supplement to subclinically malnourished village children caused an increase in growth rate, plasma amino acids, total body albumin (but not in plasma albumin level), albumin and gamma globulin turnover and plasma levels of insulin and thyroid hormones. There was a fall in plasma level of cortisol, growth hormone and in total body water, especially the extracellular compartment. The transition from subclinical malnutrition to kwashiorkor was associated with a further severe decline in protein synthesis and turnover and in the activities of several plasma enzymes. The essential role of hormonal changes in the adaptive responses to low protein intake has been emphasized. The level of hormones in plasma, as well as the concentration of total essential amino acids and the turnover of plasma proteins, are useful early indicators of the relative adequacy of protein intake by human population groups.