Nutrition Blog
June 01, 2023

Nutrition Management and PKD | Kidney Nutrition

The best nutrition care for people with kidney disease is personalized to your health goals, nutrition status, other health conditions, and blood and urine test results. One newer area of focus for personalization is the type of kidney disease, whether that is polycystic kidney disease (PKD) or chronic kidney disease (CKD).

Most of the time, when you look for nutrition information for kidney disease, it is focused on the CKD diet. Nutrition is important for people with PKD, and information specific to PKD has only recently begun to appear through research, lived experiences, and online resources.

A PKD diet can help slow the growth of cysts, which may help slow the decline in kidney function. A PKD diet can also help manage conditions such as high blood pressure, metabolic acidosis, heart disease, and kidney stones. The diet for PKD is not the same as the diet for CKD, so let’s break down some of the specific nutrition recommendations for PKD.

Fluid

One of the first recommendations for PKD is to drink more water. Ideally, fluid intake should be individualized, and take into account factors such as your activity level and other health conditions.

As a starting point, drinking 2 to 3 litres per day with PKD can help lower the hormone vasopressin (which is responsible for cyst growth) and improve urine osmolality. High urine osmolality triggers the release of vasopressin, which can affect cyst growth in PKD. For more tips on managing fluids with PKD, check out this blog post.

A common concern with higher fluid intake is frequent urination. Try spacing out your fluids and drinking throughout the day, including during the night if you wake to use the bathroom. As you make nutrition changes, such as reducing sodium intake and drinking adequate fluids, urine osmolality can improve and frequent urination may decrease.

Sodium

High sodium intake is linked to higher urine osmolality, which can cause PKD to progress more quickly due to increased cyst growth. Higher sodium intake is also associated with a greater decline in kidney function, and an increased risk of high blood pressure. Learn more in this previous blog post on high blood pressure and PKD.

The gold standard for measuring sodium intake is a 24-hour urine collection. This test, along with blood tests, can be ordered by your nephrologist or healthcare team to help guide personalized nutrition recommendations.

From a nutrition standpoint, aim for less than 2,300 mg of sodium per day. Free tools such as Cronometer or MyFitnessPal can help you track your sodium intake.

Protein

The amount and type of protein you eat are common topics of discussion with PKD. With PKD, eating too much or too little protein can affect urine osmolality. A 24-hour urine collection or working with a renal dietitian can help determine how much protein is right for you. For many people with PKD, the diet is not very low in protein, which is one of the key differences between PKD and CKD diets that research continues to explore.

When it comes to protein type, plant-based proteins offer many health benefits, including supporting kidney function and helping manage conditions such as high cholesterol and metabolic acidosis. Eating too much animal protein may increase the risk of gout and kidney stones. Including more plant-based proteins is a healthy approach for PKD. Try starting with one meatless meal per week or per day and build from there.

It is also important to consider when you eat protein. Since your kidneys can only filter so much at one time, spreading protein intake evenly throughout the day can be helpful. This approach can also help you feel full for longer.

Other Considerations

Ketogenic Diets

You may be wondering about keto diets. While there is promising research on keto diets and PKD, there is currently no consensus statement.

A keto diet places the body into nutritional ketosis, and concerns have been raised about its safety and long-term sustainability. In contrast, a low-carbohydrate diet focuses on reducing carbohydrates while choosing nutrient-dense foods.

With PKD, both the type and amount of carbohydrates matter. When including carbohydrates, aim for whole grains such as whole grain bread, brown rice, barley, and oatmeal instead of refined carbohydrates.

Heart-Healthy Diets

The connection between heart disease and PKD is strong, making it important to follow an eating pattern that supports both kidney and heart health. This may include choosing low-fat dairy products, nuts, seeds, legumes, and beans more often.

If you include animal proteins, aim for fatty fish such as salmon, trout, or mackerel twice per week. Choose unsaturated fats like olive oil or other non-tropical oils for cooking.

Diets such as the Mediterranean diet or the DASH diet can support both kidney and heart health.

Potassium

Potassium intake should be individualized based on your blood work. Many people with PKD do not need to restrict potassium. Potassium from vegetables, fruits, whole grains, and plant-based proteins can help manage blood pressure.

Phosphorus

Foods with added phosphorus should be avoided by anyone with kidney disease, making it important to read nutrition labels. Other sources of phosphorus can usually be included in a PKD diet unless your healthcare team advises otherwise.

Oxalates

Oxalates are compounds found in many foods, mainly from plant sources. High levels of oxalate in the urine can lead to calcium oxalate kidney stones. With PKD, it may be helpful to limit certain high-oxalate foods such as spinach, beets, oranges, raspberries, and almonds to reduce the risk of kidney stones.

Pairing oxalate-containing foods with calcium can reduce oxalate absorption in the gut and help prevent stones. More information on this topic will be shared in future blog posts.

So, what’s next?

When making nutrition changes with PKD, start with these tips:

  • Aim for half your plate to be vegetables (choose lower potassium or lower oxalate options if needed)
  • Choose plant-based proteins more often (select lower oxalate options if needed)
  • If including carbohydrates, choose whole grains more often
  • Limit sodium by reading food labels, eating at home more often, and cooking with herbs and spices
  • Make water your beverage of choice

Working with your nephrologist or healthcare team to complete a 24-hour urine collection, and partnering with a renal dietitian, can help you create a personalized nutrition plan that meets your needs.

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About the Author

Emily Campbell, RD, CDE, MScFN, is a Registered Dietitian and Certified Diabetes Educator with a master’s degree in foods and nutrition. Emily specializes in helping people with kidney disease navigate the often confusing world of nutrition to support better health. Emily can be found at kidneynutrition.ca.