Ask the Experts - Dietary Recommendations for Patients With Diabetic...
Ask the Experts - Dietary Recommendations for Patients With Diabetic...
What are the specific dietary recommendations for patients with diabetic nephropathy?
Jose D. Beswilan, MD
Data from experimental diabetic animal models have established an important ameliorating role of dietary protein restriction on the progress of kidney damage. The scientific basis for these observations is unclear but may relate to the ability of amino acids to raise glomerular filtration rate (GFR) and perhaps exacerbate hemodynamic insult to the glomerulus. Moreover, lowering dietary protein reduces proteinuria, which may in turn prevent continuing tubular damage and prevent progression.
However, the results in humans are conflicting. The EURODIAB survey in patients with type 1 diabetes showed an association between high dietary protein intake and presence of nephropathy, and data from small, short-term intervention studies have suggested a positive benefit of restricted protein intake on nephropathy progression. A meta-analysis of the majority of these trials has revealed that there is a probable benefit in diabetic but not other nephropathies. This conclusion has led to the current Position Statement of the American Diabetes Association, which states, "...the general consensus is to prescribe a protein intake approximately equal to the adult recommended dietary allowance (RDA) of 0.8g/kg body weight per day (~ 10 % of daily calories)...once the GFR begins to fall, further restriction to 0.6g/kg body weight per day may prove useful in slowing decline..."
There are several problems with this advice:
Another important dietary consideration relates to salt intake. Generally, Western diets are high in salt and this contributes to hypertension as well as to blunting the effectiveness of antihypertensive treatments, specifically ACE inhibitors or angiotensin II receptor blockers (AIIRBs). This is because a high salt intake will suppress the activity of the renin angiotensin system and thus diminish the ability of blocking drugs to lower blood pressure. In this regard it is also important to advise against proprietary
Lo-Salt
preparations, as these often contain potassium chloride, which must be taken with caution in renal impairment or when on ACE inhibitors or AIIRBs because of their potassium-retaining potential. Because patients with nephropathy have a higher risk for cardiovascular disease, they should also be given advice about fat and cholesterol intake. Any dietary advice should be given by trained staff familiar with the complex requirements of patients with both diabetes and renal impairment.
What are the specific dietary recommendations for patients with diabetic nephropathy?
Jose D. Beswilan, MD
Data from experimental diabetic animal models have established an important ameliorating role of dietary protein restriction on the progress of kidney damage. The scientific basis for these observations is unclear but may relate to the ability of amino acids to raise glomerular filtration rate (GFR) and perhaps exacerbate hemodynamic insult to the glomerulus. Moreover, lowering dietary protein reduces proteinuria, which may in turn prevent continuing tubular damage and prevent progression.
However, the results in humans are conflicting. The EURODIAB survey in patients with type 1 diabetes showed an association between high dietary protein intake and presence of nephropathy, and data from small, short-term intervention studies have suggested a positive benefit of restricted protein intake on nephropathy progression. A meta-analysis of the majority of these trials has revealed that there is a probable benefit in diabetic but not other nephropathies. This conclusion has led to the current Position Statement of the American Diabetes Association, which states, "...the general consensus is to prescribe a protein intake approximately equal to the adult recommended dietary allowance (RDA) of 0.8g/kg body weight per day (~ 10 % of daily calories)...once the GFR begins to fall, further restriction to 0.6g/kg body weight per day may prove useful in slowing decline..."
There are several problems with this advice:
Data in type 2 diabetes are inadequate.
There may be potential for protein malnutrition, particularly if the patients are nephrotic.
Ability to comply with further dietary advice is difficult for many patients.
There may be qualitative differences between proteins of animal and vegetable origin.
Another important dietary consideration relates to salt intake. Generally, Western diets are high in salt and this contributes to hypertension as well as to blunting the effectiveness of antihypertensive treatments, specifically ACE inhibitors or angiotensin II receptor blockers (AIIRBs). This is because a high salt intake will suppress the activity of the renin angiotensin system and thus diminish the ability of blocking drugs to lower blood pressure. In this regard it is also important to advise against proprietary
Lo-Salt
preparations, as these often contain potassium chloride, which must be taken with caution in renal impairment or when on ACE inhibitors or AIIRBs because of their potassium-retaining potential. Because patients with nephropathy have a higher risk for cardiovascular disease, they should also be given advice about fat and cholesterol intake. Any dietary advice should be given by trained staff familiar with the complex requirements of patients with both diabetes and renal impairment.
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