It has been proposed that a low-protein diet will slow progression of chronic kidney disease although studies have not always supported this belief. The accepted practice is that 60% to 70% of protein comes from high biological value (HBV) protein, but this limits patient choice and patients struggle to follow the diet. When a diet with only 30% HBV protein was trialed, there was a significant increase in serum bicarbonate, and patients preferred the diet. The dietary advice given in predialysis clinics was changed.