Role of dietary factors in the progression of chronic renal disease

Abstract

The available evidence indicates a pronounced effect of protein intake on the deterioration of renal function in several widely differing experimental models of renal disease in rats and mice. The evidence that similar effects occur in humans is suggestive but tenuous. Although the 'hyperfiltration theory' provides a logical explanation for a link between dietary protein intake and the progressive loss of renal function, the mechanisms by which decreases in protein intake may attenuate the progression of renal disease have not been unequivocally established. Decreases in protein intake may modify immunological events, decrease hypertrophy and hyperfiltration in remaining nephrons, affect lipid metabolism, prevent abnormalities in coagulation, alter hormonal secretion and/or effects. All of these factors alone or in combination may play a role in the progression of renal disease. In addition, studies are required to determine 'safe' limits for protein restriction so as to avoid prolonged negative nitrogen balance and malnutrition. The evidence for a role of dietary phosphate in the progression of renal disease is not compelling. The potential role of lipids, although suggestive, is not conclusive. It is possible that each one, protein, phosphate and lipid content of the diet, plays a role in the progression of renal disease. The relative importance of these dietary components may vary depending on the pathogenesis, stage, and mechanisms of progression of any given renal disease. The implications that dietary manipulations may halt or delay the progression of renal disease are enormous. The time is ripe for adequately controlled prospective studies in humans to test the validity of some of the hypotheses proposed. Such studies should carefully consider not only the criteria needed to evaluate the effect of dietary manipulations on the course of renal disease but also the nutritional requirements and current intakes of protein, phosphate, and fatty acids in humans.