The rate of diabetes in Canada is increasing and people with diabetes are living longer, consequently, we are seeing a steady increase in diabetic nephropathy in this population. In 2000 the WHO estimated there to be 171 million people with diabetes worldwide and that by 2030 this number would be expected to more than double to a total of 366 million(1). A Statistics Canada Health Survey demonstrated in 2006 that about 1.3 million Canadians over the age of 12 reported that they have been diagnosed with diabetes, this is 5% of the Canadian population(2). Over the last 10 years the number of newly diagnosed end-stage renal disease (ESRD) patients with diabetes increased by 114% (from 1,066 in 1995 to 2,139 in 2004). This increase correlates with the increase in the incidence of diabetes in the Canadian population. More than 40% of those with ESRD also have diabetes(3). Over the coming years, as diabetes educators, we need to prepare ourselves to counsel more patients with diabetes complications including diabetic nephropathy.
Having spent my last few years working in a diabetes centre counseling clients with diabetes it has been quite an adjustment for me to move to an in-patient nephrology floor. In the diabetes centre I spent a lot of time talking to my clients about the benefits of choosing high fibre grains and cereals, filing half their plate with vegetables, having a variety of fruit throughout the day, not eating too much animal protein and ensuring that they met Canada’s Food Guide (CFG) requirements for low-fat dairy foods. Suddenly, I am required to counsel the opposite of what I came to believe was a healthy diet, not only for those with diabetes, but also the general population. In contrast, I now counsel my clients to choose refined grain products and avoid many that are high fibre, limit the variety of fruits and vegetables, cut back on their dairy products and sometimes increase their animal protein intake. If this is a difficult concept for me to overcome, just imagine how our diabetes clients who have developed renal disease must feel. Many of them have struggled to make the diet and lifestyle changes we suggested when they were seen in the diabetes center. Now, another dietitian (or in some cases, perhaps the same dietitian), is telling them the opposite of what they may have strived so hard to change.
Considerations for a Renal Diet
The onset and progression of diabetic nephropathy maybe gradual or rapid. Dietary recommendations are tailored to the individual and the stage of their diabetic nephropathy. Below is a summary of the potential changes in diet that our clients with diabetic nephropathy may face along their renal failure journey.
As kidney function declines, so does the kidney’s ability to filter potassium. A consequent rise in serum potassium can lead to cardiac arrthymias and at higher levels may cause cardiac arrest. In pre-end stage renal disease (ESRD) dietary potassium may have to be restricted depending on serum potassium levels. Clients with ESRD, on hemodialysis, generally need to follow a potassium-restricted diet. However, due to frequent filtration, clients on peritoneal dialysis don’t usually need to restrict potassium, on the contrary, they often need to supplement high potassium foods as their serum potassium may be low. Hyperglycemia and some hypertension medications can also cause hyperkalemia, requiring a low potassium diet.
Some common high potassium foods that may need to be restricted:
|Apricot||Asparagus||Multi-grain breads||Nuts & seeds|
|Banana||Sweet potato||Wholegrain cereals||Legumes|
|Orange||Avocado||Wholegrain pasta||Salt substitutes|
|Cantaloupe||Squash||Wholegrain cookies||Brown sugar|
|Dried fruit||Yam||Wholegrain crackers||Molasses|
Some common low potassium foods that may be consumed in moderation:
|Blueberries||Cucumber||Rice cereal||Sugar substitute|
|Raspberries||Eggplant||Cream of wheat||White sugar|
|Peach (canned)||Green beans||White rice||
|Pineapple||Yellow beans||White pasta & noodles||
Serum phosphorous levels in clients with renal failure rise as a result of the kidneys’ inability to maintain electrolyte balance. Excess serum phosphorous leads to withdrawal of calcium from the bones causing bone demineralization(4). An increase in serum phosphorous and calcium can also lead to metastatic calcification. There is evidence that a dietary phosphorous restriction in early renal failure may help slow the progression of renal disease(5). Phosphate binders (e.g. Tums, CaCO3, Renagel or Amphojel) can be taken at meals to bind excess phosphorous in the intestines so that it is excreted and not absorbed. Many clients with ESRD will require a dietary phosphorous restriction together with phosphate binders. This will help control their serum phosphorous levels preventing metastatic calcification and maintaining their bone health.
Some common high phosphorous foods that may need to be restricted:
|Cheese||Corn||Multigrain breads||Nuts & nut butters|
|Offal||Green peas||Wholegrain cereals||Seeds|
|Legumes||Potato||Wholegrain pasta||Cola products|
|Wholegrain rice||Malted milk|
|Wholegrain cookies||Baking powder|
Low phosphorous foods that can be substituted for high phosphorous foods:
|Instead of:||mg PO4||Choose:||mg PO4|
|Milk (1 cup)||
|Nondairy creamer (1 cup)||
|Hard cheese (1 oz)||
|Cream cheese (1 oz)||
|Ice-cream (1/2 cup)||
|Sherbert (1/2 cup)||
|Peanuts (2 oz)||
|Low fat/salt popcorn (1 1/2 cups)||
|Oatmeal (1 cup)||
|Cream of wheat||
|Raisin Bran (1 oz or 3/4 cup)||
|Cornflakes (1 oz or 1 1/4 cup)||
|Diet coke (1 can)||
|Diet gingerale (1 can)||
Some studies have shown that protein restriction reduced the risk for decline in the glomerular filtration rate (GFR) or creatinine clearance. A moderately low protein diet of < 0.8 – 0.9 g/kg/day can be used in pre-dialysis renal failure(6). When clients start dialysis they will require larger amounts of protein (1.2-1.3 g/kg/day) to help replace losses from dialysis and also to help prevent malnutrition which is common in this population. It is recommended that clients aim for 60% high biological value (HBV) protein. As HBV protein sources are also high in phosphorous, the use of phosphate binders is usually indicated to help bind the excess phosphorous.
Sources of HBV protein:
Protein sources high in phosphorous and potassium:
- Nut butters
Many patients with diabetic nephropathy also suffer from hypertension. Reducing their dietary sodium may help reduce hypertension and further damage to the kidneys. Those clients on hemodialysis may require a sodium restriction to help prevent thirst and excess fluid intake that could lead to fluid retention between dialysis treatments.
Fluid may be restricted in renal failure due to fluid retention between dialysis treatments especially in those clients on hemodialysis who are anuric or oliguric.
Vitamins and minerals
Supplementation of vitamin A in renal disease in contraindicated due to toxicity. Vitamin C intake should be limited to less than 100 mg/day due to the risk of formation of oxalate stones. Folic acid and vitamin B12 are recommended for clients with renal disease to replaces losses during dialysis and support red blood cell (RBC) production(7). Vitamin D metabolism is alterered in clients with renal disease and often supplementation is required in the form of active vitamin D3 (Calcitriol). On hemodialysis loss of blood can lead to anemia, therefore, iron replacement to facilitate the replacement of RBC is often required. Iron supplements with ascorbic acid should be avoided due to there vitamin C content(8) . Erythropoietin may also be required to replace the natural hormone that clients with renal failure may lack.
How do we help our diabetes clients make diet changes when they develop diabetic nephropathy?
I like to start with explaining the rationale for renal diet recommendations. It is easy to give clients a list of high potassium foods and tell them to limit or avoid them, but they are more likely to follow these recommendations if they know that eating too many bananas could cause them to have a heart attack!
Getting clients involved in looking at their current diet and figuring out together how they can make changes allows them to take ownership of their health and new diet. A diet they have helped to modify is a diet they are more likely to stick to.
The table below summaries, by food group, some of the main differences between a diabetes diet and a diet to help manage renal failure:
|Grain products||Increase use of low glycemic index (GI) foods such as barley, pasta and whole intact grains. Eat more high fibre foods.||May need to restrict high fibre and many low GI grains as they are high in potassium and phosphorous.|
|Fruits||Emphasis choosing a variety of whole fruits.||Many fruits may need to be restricted as they are high in potassium.|
|Vegetables||Fill ½ your plate with a variety of brightly coloured vegetables.||Many vegetables may need to be restricted as they are high in potassium and phosphorous.|
|HBV protein||Protein intake should be 0.86 g/kg/day.||Protein recommendations range between 0.8-0.9 g/kg/day pre-dialysis and 1.2-1.3 g/kg/day for dialysis. >60% HBV protein.|
|Vegetarian protein||Vegetarian proteins should be considered as an alternative to animal proteins.||Vegetarian protein sources may need to be restricted as they are high in potassium.|
|Diary products||Have a glass of milk with your meals. Follow CFG for recommendations on dairy products.||Milk and dairy products are often restricted as they are high in phosphorous and potassium.|
Adapted from: Just the Basic (CDA) and the Manual of Clinical Dietetics
Slowing the progression of renal failure – how can we help our clients?
The earliest sign of diabetic nephropathy is microalbuminuria. Diagnosis of microalbuminuria can identify individuals at high risk of the development of progressive nephropathy(6). Recent trials have shown that intervention at this stage to improve metabolic and blood pressure control can prevent the progression to overt diabetic nephropathy(9).
As diabetes educators we can help our clients to delay or slow the progression of diabetic nephropathy by counseling them on the following:
- The best possible glucose control through diet, exercise and medication if necessary.
- Diet and lifestyle changes to help normalize body mass and lower blood pressure.
- A moderately low protein diet (< 0.8-0.9 g/kg/day).
- Regular screening for microalbuminuria. 5. Ensuring those with microalbuminuria are being treated with the appropriate medications e.g. ACE inhibitors.
Adapted from: the Clinical Practice Guidelines for the Management of Diabetic Nephropathy in Canada6.
From brown bread to white and back to brown again…
To end on a positive note, those patients lucky enough to receive a successful kidney transplant can throw many of their diet restrictions out of the window post transplant and return to following a healthy diabetes style diet – they may of course need to see their diabetes educators again in case they have forgotten what it is they are supposed to eat!
- WHO diabetes programme, sept 18, 2006 www.who.int/diabetes/en
- Statistics Canada “Canadian Community Health Survey: New Data on Smoking and Diabetes; The Daily (June 13, 2006) http://www.statcan.ca/daily/english/060613/d060613a.htm
- Focus on Diabetes in End-Stage Organ Disease in Canada. Canadian Institute for Health Information. Feb 2007. http://secure.cihi.ca
- Beto, J. Which diet for which renal failure: Making sense of the options. J Am Diet Assoc. 1995; 95:898-903
- Maroni, BJ. Role of nutrition in prevention of the progression of renal disease. Annu Rev Nutr. 1997; 17:435-455
- Steel, A. Clinical Practice Guidelines for the Management of Diabetic Nephropathy in Canada. Canadian Journal fo Diabetes Care 23:2 53-61
- Makoff, R. Water-soluble vitamin status in patients with renal disease treated with hemodialysis or peritoneal dialysis. J Renal Nutr. 1991; 1:56-73
- Moore, LW. Incidence causes and treatment of iron deficiency anemia in hemodialysis patients. J Renal Nutr. 1992; 2:105-112
- Pedrini, MT. The effect of dietary protein restriction on the progression of diabetic and nondiabetic renal disease: A meta analysis. Ann Intern Med. 1996; 124: 627-632