The phrase “renal diet” may be one of the most confusing in the nutrition world. If you Google it, you will find endless lists of foods to avoid. These lists and advice are often conflicting, which can be confusing and frustrating.
You may even find websites that claim foods or regimens will “cure” kidney disease. This is completely bogus 99% of the time, and these recommendations can be dangerous to people with kidney disease. I’d steer clear of sites making claims like these.
Read on to understand what a renal diet is and what it means for you.
What Does a “Renal Diet” Mean?
“Renal” is simply a fancy word for “kidney”. In the medical world, kidney has many different names including “renal” and “neph”. For example, the formal title for your kidney doctor is a “nephrologist”.
So, a renal diet is a diet that is good for kidneys. The kicker is, there is no single renal diet that is right for everyone. A healthy renal diet for you is very dependent on what kind of kidney disease you have, what your kidney function is, and what your other labs look like.
Know that there is no single food that will cure or prevent progression of kidney disease. A healthy renal diet must focus on whole diet patterns instead of eating (or limiting!) single foods.
A Renal Diet is Different For Everyone!
Some of the “renal diet” confusion comes from the fact that a kidney friendly diet is not the same for everyone. For example, a renal diet for someone with early stages of kidney disease is very different than a renal diet for the later stages of disease.
To complicate things further, both of those diets are different than a renal diet for someone who is on dialysis or has a history of kidney stones. No wonder everyone is confused!
Here is an overview of how the recommendations for a renal diet differ. This will help you learn what a renal diet is for you.
What Is a Renal Diet for Chronic Kidney Disease?
A renal diet for Chronic Kidney Disease (CKD) changes drastically depending on the stage of CKD you have. I’ll walk you through each aspect of a renal diet for CKD and help you understand how needs change.
For all stages of kidney disease, sodium should be limited to 1,500-2,300mg per day on a renal diet. (1) This helps control blood pressure (which is key to preventing more kidney damage!) and swelling.
Keeping sodium in check can also help lower the amount of protein in your urine.
In CKD stage 1-3a (or, a GFR of 45ml/min or more), a healthy renal diet is moderately low in protein. Most people should aim for 0.8 grams of protein per kilogram body weight per day in these early stages. This is plenty of protein to maintain or build muscle!
If CKD progresses to stages 3b-5 (or, a GFR less than 45ml/min), protein recommendations go down. For this stage, the National Kidney Foundation recommends a protein intake between 0.55-0.6 g/kg body weight. (1)
Of note, people who have both diabetes and CKD should not limit protein this much. Aim for 0.8 g/kg body weight if you have diabetes. (1)
On dialysis, protein needs increase. A diet high in protein is important to maintain muscle and prevent poor nutrition in people on dialysis. Protein recommendations go up to 1.2 grams of protein per kilogram body weight per day for people on dialysis. (1)
Protein needs are tricky and may be different based on your body size, nutrition status, medical history, and age. Ask your dietitian how much protein is right for you!
On a renal diet, dietary potassium only needs to be limited in people with high blood potassium. In the early stages of kidney disease, blood potassium levels are usually normal! In fact, a diet high in potassium can help control blood pressure and protect your kidneys. (2)
If kidney disease progresses to stage 4 or 5, high blood potassium levels (aka hyperkalemia) are more common. The kidneys are not able to get rid of potassium as well. Potassium can build up in your body and, in severe cases, cause serious issues like heart arrhythmias. If your blood potassium level is high, then cutting back how much potassium you eat is a good idea. (1)
Artificial phosphorus should be limited for nearly everyone with kidney disease, no matter the stage.
High levels of phosphorus can cause bone disease, heart disease and even faster progression of kidney disease.
Natural sources of phosphorus, such as in whole grains, beans, nuts, seeds, and lentils, usually do not need to be restricted until very advanced CKD (if ever). This is especially true if phosphorus from animal products is avoided and plant proteins are used in place of meat, chicken and fish at meals.
Dietary Acid Load
Dietary acid load primarily comes from animal protein. Fruits and vegetables help neutralize acid. This is why it is so important that any renal diet include PLENTY of fruits and veggies, no matter the stage!
Aim for at least 5 servings of fruits and vegetables every day.
Plant proteins produce significantly less acid than animal proteins. Eating more plant proteins like nuts, seeds, lentils, whole grains, and beans in place of animal proteins can slow CKD progression.
Both dehydration and not drinking enough fluid can hurt kidneys. However, most people with kidney disease do not need to limit fluid unless kidney disease is very advanced. Most people on a renal diet for kidney disease should drink about 2 liters of water each day.
However, people with some health conditions may need to limit fluid. Here are some examples:
- Advanced stages of CKD
- Heart failure
- Liver failure
Fluid needs on a renal diet are tricky! Ask your doctor how much fluid is right for you.
What Is a Renal Diet for Polycystic Kidney Disease?
A renal diet for polycystic kidney disease (PKD) is based on GFR level and what stage of CKD you have. If you have PKD with normal kidney function (GFR >90ml/min), you have stage 1 CKD.
Please refer to the “What Is a Renal Diet for Chronic Kidney Disease?” above for more specific recommendations.
Sodium and fluid are especially important on a renal diet for people with PKD. Eating too much salt can cause faster cyst growth, in addition to raising blood pressure. (5)
A very high fluid intake is often recommended for people with PKD to slow cyst growth too! Drinking 3-4 liters of fluid each day reduces a hormone called “vasopressin”. Vasopressin can accelerate cyst growth in PKD. So, drinking a lot of water can help slow cyst growth. (5)
There are some new studies done in animals showing some promising benefits of a keto diet for PKD. However, more research is needed before this diet should be recommended to people with PKD. Learn more about the keto diet and PKD.
What Is a Renal Diet for People with a Kidney Transplant?
Nutrition is an important piece of protecting a new kidney! A renal diet after kidney transplant is individual to your lab values.
For most people, a renal diet after transplant is similar to the early stages of CKD. It is best to limit sodium and large amounts of protein, especially animal protein. Focusing on eating lots of fruits and vegetables will help keep your new kidney working as long as possible!
Food safety is also important for people with a transplant. Transplant medications impact your immune system and increase risk of foodborne illness. Learn how to keep your food safe!
What Is a Renal Diet for Proteinuria?
Proteinuria (or, too much protein in your urine) often goes hand-in-hand with kidney disease. Proteinuria is especially common for people who have kidney disease as a result of diabetes.
Kidney disease with proteinuria is usually more severe and progresses faster. So, we want to do everything we can to keep urine protein levels down!
Limiting protein (based on your stage of CKD) and sodium to 2,300mg/day will help lower protein in your urine. (1)
What Is a Renal Diet for Glomerulonephritis?
There are no special nutrition recommendations for glomerulonephritis. A renal diet for glomerulonephritis should be based on your GFR and stage of kidney disease.
What Is a Renal Diet for Kidney Stones?
There is no one renal diet that is good for kidney stones. Healthy eating for kidney stones is based on the type of stone you make and your 24-hour urine results. In my course, Kidney Stone Nutrition School, I teach you how to interpret your 24 hour urine results and tailor your diet for maximum stone prevention.
Calcium oxalate kidney stones are most common, and make up about 80% of kidney stones. The most common urine risk factor for kidney stones is hypercalciuria (or, high urine calcium). A dietary pattern that limits sodium to 2,300mg, non-dairy animal protein and added sugar can help lower urine calcium. (6)
No matter the type of kidney stone, drinking at least 3 liters of fluid each day is very important.
A low oxalate diet may also be important for kidney stone prevention. But, this is not the case for everyone.
Learn more about nutrition for calcium oxalate kidney stones. Or, read more about uric acid kidney stones.
Getting Help For a Renal Diet
As you can see, there really is NO one “renal diet”. A renal diet is individualized to your labs and medical history.
Putting all of this information together to figure out what to eat can be overwhelming. I highly recommend asking your nephrologist for a referral to meet with a Registered Dietitian to help you.
In the United States, most insurance covers dietitian visits for kidney disease! It is never too early (or, too late!) to work with a dietitian for kidney health.
For more help with kidney stones, check out my online course, Kidney Stone Nutrition School.
For more help with kidney disease, check out my resources page for a list of renal dietitians I love!
I also have a list of dietitians who specialize in kidney disease and have virtual practices on my resources page. The Academy of Nutrition & Dietetics and the National Kidney Foundation also have tools to help you find a renal dietitian near you!