People living with diabetes are at risk of developing kidney disease – diabetic nephropathy.

Diabetic nephropathy occurs when the small blood vessels in the kidneys become damaged from high blood glucose levels.

The role of the kidney is to filter the blood and pass waste products and excess fluid into the urine. When the kidney filters become damaged, there can be a build-up of waste products and fluid in the body. The most common cause of kidney disease is diabetes and high blood pressure.

Kidney disease is progressive and once it becomes severe, dialysis or a kidney transplant is required. If you have been told you have chronic kidney disease or diabetic nephropathy it is important that you make some dietary changes.

The benefit of improving your diet

You can look after your kidneys by making certain food choices. Your diet can:

• Reduce the amount of work for the kidneys
• Slow down the decline of the kidneys

What should you eat if you have kidney disease?

Kidney disease has different stages which relate to how well the kidneys are working. There are different guidelines for different stages of kidney disease, and it is always best to work with an accredited practising dietitian to understand the best diet for you.

The following information contains general advice for reducing stress and slowing down the decline of the kidney.

Salt (sodium)

It is impossible to talk about kidney health without talking about salt. That is because when we eat too much salt, our body holds onto more fluid. This can lead to swelling in the feet, ankles, legs and hands, shortness of breath and high blood pressure.

Eating less salt can help to reduce your blood pressure and create less work for the kidneys. The recommended daily intake of salt is less than 2300mg per day (which is about 1 teaspoon). The average person eats almost twice this amount.

Often, it is assumed that salt mostly comes from the salt we add to our home-cooked meals – this is not actually the case! Most of our salt comes from processed foods, with the main sources in a typical Australian diet coming from cereals, milk products, processed meats (such as ham, bacon and sausages) and snack foods. Other food products that also contain high amounts of salt are bread, cheese, takeaway foods and off-the-shelf sauces and dressings.

Strategies to lower your salt intake

• Eat mostly fresh foods such as vegetables, fruit, unprocessed and unseasoned meats, fish and poultry
• Limit your intake of packaged, processed foods
• Look for foods labelled as – salt free, very low salt, reduced salt, no added salt, unsalted and lightly salted
• Select food products with less than 400mg sodium per 100g

Hot tip!

• Download the FoodSwitch app on your smartphone
• Turn on the ‘Salt Switch’ filter

Scan barcodes and find easy product-swaps that are lower in salt.

Protein

We need protein in our diet to build muscle, repair tissue, fight infections and stay well. However, when we eat more protein than our body needs, it is turned into urea and removed by the kidneys.

Eating too much protein creates more work for the kidneys. Reducing protein intake has been shown to reduce stress on the kidneys.

What you can do

• Check your portion size of high protein foods such as chicken, beef, lamb, fish, tofu and eggs
• Keep your protein portions to the size of your palm
• Fill only ¼ of your dinner plate with high-protein foods
• Have one or more meat-free meals per week
• Swap animal-proteins for plant-based proteins such as kidney beans, chickpeas, tofu and lentils

What about carbohydrates?

Having high blood glucose levels can make kidney disease worse. Whereas, good glycaemic control can slow the progression of kidney disease. A sign of good glycaemic control is an HbA1c of less than 7%.

The carbohydrate recommendations for people with kidney disease are no different from the advice for people living with diabetes. This includes:

• Eating low-GI carbohydrates
• Limiting intake of high-sugar foods
• Sticking to the standard serving sizes for carbohydrate-containing foods such as dairy, fruit and grains
• Selecting grain-based foods that are high in fibre
• Spreading carbohydrates out across the day
• Eating carbohydrates with a small serve of lean-proteins and plenty of vegetables

Remember if you are trying to portion-control your protein and carbohydrates because you have kidney disease and diabetes, it always helps to fill your plate with lots of vegetables or salad.

Potassium and Phosphate

Potassium and phosphate are other micronutrients that are filtered by the kidneys. If kidney disease progresses, the kidneys may no longer be able to remove enough of the extra potassium and phosphate from your blood, and you may be instructed to limit your intake.

This is only necessary if you are advised by your doctor and would be best to do under supervision of a dietitian.

Plant-based diets for diabetes and kidney disease

Plant-based diets are becoming more popular and recognised for their health benefits for both diabetes and kidney disease. They consist mostly of vegetables, wholegrains, legumes, fruits and nuts. They usually contain small amounts of animal-products and minimal amounts of processed foods. An example of a plant-based diet is the Mediterranean Diet.

Some of the benefits of eating a plant-based diet for kidney disease are:

• Low intake of salt which reduces stress on the kidneys
• High intake of vegetables which keeps you feeling full
• Smaller portions of proteins and less production of urea and less workload for the kidneys
• Reduced acid-load in the body which can make kidney disease worse
• High intakes of beneficial nutrients such as antioxidants and fibre

Key Points

• Diabetic nephropathy is a type of kidney disease
• Kidney disease is made worse by high blood pressure and high blood glucose levels
• You can slow down the progression of kidney disease by:
  • Keeping blood glucose levels in target
  • Lowering or maintaining blood-pressure in target range
• You can also look after your kidneys by reducing their workload
• This is achieved by:
  • Eating less than 2300mg salt per day
  • Sticking to the recommended portion-sizes of high protein foods
• Plant-based diets have health benefits for both diabetes and kidney disease
• If kidney disease progresses you may have to change your diet, this should be done with the advice of your healthcare team

Further information

• Kidney Health Australia – Nutrition and Kidney Failure Factsheets (available in 17 languages)
• Bush Tucker and Kidney Disease Booklet – Guidelines for people with chronic kidney disease who wish to eat Indigenous foods.
• Nutrition and Early-Stage Kidney Disease – Nutrition Education Material Online (NEMO)

 Charlotte Lentfer, APD