The effect of caloric intake on nitrogen balance in chronic renal failure.

Giordano (1963) demonstrated that nitrogen equilibrium could be achieved in chronic renal failure on a nitrogen intake which was less than the minimal nitrogen requirement for normal subjects. His diet was mainly synthetic, and a practical diet with low-protein foods was first devised by Giovannetti & Maggiore (1964), later modified to suit British palates by Shaw, Bazzard, Booth, Nilwarangkur & Berlyne (1965). This diet contained a large proportion of high-biological-value protein providing all the essential amino acids except methionine in the amounts recommended by Rose, Wixom, Lockhart & Lambert (1955), a methionine supplement and an adequate supply of calories. Since that time there has been considerable controversy about the minimal nitrogen requirement for equilibrium in chronic renal failure. Shaw et al. (1965) recommended 0.26 g of protein per kg/body weight, Giovannetti & Maggiore (1964) 0.3 g and Ford, Phillips, Toye, Luck & de Wardener (1969) 0.5 g. Giovannetti (1966) stated that for the diet to be successful a high caloric intake was necessary. Ford et al. (1969) concluded that caloric intake had no effect on nitrogen metabolism in chronic renal failure. However, since their experimental protocol did not compare the effects of changing caloric intakes on nitrogen balance while on isonitrogenous diets, their nitrogen intake changing over a fourfold range, no firm conclusions can be drawn. We report here the results of an investigation into the effect of caloric intake on nitrogen metabolism in chronic renal failure.