Dietary manipulation of plasma albumin concentration.

The variation in plasma albumin concentrations of rats fed a wide range of protein- and energy-deficient diets has been investigated. These changes have been correlated with simultaneous effects of the diets on growth rate, carcass composition, protein and energy balance, and plasma concentration of insulin corticosterone and triiodothyronine (T3). Although rats eating diets of low protein content and libitum developed hypoalbuminemia, those fed equivalent amounts of protein at low energy intakes had plasma albumin concentrations nearer, or equal to control values. Data from the balance study showed that for hypoalbuminemia to occur, not only had dietary protein to be inadequate, it was also necessary for energy consumption to be in excess of requirements. It is suggested that in protein-deficient animals, energy consumed in excess of the amount required for maintenance and the protein-limited growth rate initiates a metabolic response which results in inappropriate use of the meagre protein intake. This "dysadapted" state, in the rat, appears to be indicated by elevated plasma T3 values. The implication that kwashiorkor-like symptoms can be generated by a relative as opposed to a total energy excess is discussed in relation to the appearance of this disease in humans.