What does a “Renal Diet” mean?
The phrase “renal diet” may be one of the most confusing in the nutrition world. If you Google this phrase, you will find endless recommendations and lists of foods to avoid and foods that alone will “cure” kidney disease. You might find recommendations to avoid all potassium and phosphorus. You may find recommendations to avoid whole grains and chocolate, to eat meat, to eat more protein and to avoid some vegetables. These lists and conflicting advice can be confusing and frustrating. You just want to figure how to eat right for their kidneys! Although there may be some truth in all of these recommendations, they are not relevant for everyone with kidney disease. The diet right for you is very dependent on what kidney disease you have, what your kidney function is right now and what your other labs look like. Also, unfortunately there is no single food that will cure or prevent progression of kidney disease. The focus should be on whole diet patterns instead of on single foods.
Firstly, what does the word “renal” even mean!? Renal is simply another 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.
A “Renal Diet” is not the same for everyone!
Some of the “renal diet” confusion comes from the fact that a healthy kidney diet is not the same for everyone with kidney disease. A diet healthy for someone with early stages of kidney disease is very different than a healthy diet for the later stages of disease. Both of those diets are different for someone who is on dialysis or has a history of kidney stones. No wonder everyone is confused! Here is a brief description of how the recommendations for a healthy diet change as kidney disease progresses:
Early Stages of Chronic Kidney Disease (GFR* of greater than 20ml/min)
Most people in this stage of kidney disease should focus on eating lots (and ALL types!) of fruits and vegetables, whole grains, small amounts of meat/chicken/fish or switching to plant proteins. Avoiding too much sodium (salt) is important to help control blood pressure or keep blood pressure in a healthy range. Avoid artificial phosphorus in processed foods. Adequate hydration is important.
Later Stages of Chronic Kidney Disease WITHOUT Dialysis (GFR* of less than 20ml/min)
The diet for this stage of Chronic Kidney Disease is very similar to the diet for the early stages of kidney disease. Some people may have to start limiting how much potassium they eat, but this is not true for everyone in the later stages of disease. You need to limit dietary potassium if the amount of potassium in your blood is too high. Or, if you are taking certain medications (called “ACE inhibitors” or “ARBs). It is important to ask your healthcare provider if you should cut back on how much potassium you eat. Potassium is very good for most people as it helps control blood pressure. Cutting back in how much potassium you eat could rob you of the benefits of potassium and many delicious, healthy foods! Cutting back on sodium and artificial phosphorus & maintaining good hydration are still important.
People Who Are On Dialysis
People who are on dialysis have a very specific diet to help alleviate the side effects of dialysis and health consequences of Chronic Kidney Disease. Most people on dialysis need to restrict how much potassium and phosphorus they eat. Depending on their labs, they may need to restrict natural sources of phosphorus in addition to artificial sources. Eating lots of protein is important for dialysis patients as many unfortunately suffer from malnutrition. In addition, you may need to cut back on fluid, depending on how much water your body is holding onto and how much urine your body makes. It is critical for you to work with a dietitian to learn more about the specifics of what diet is best for YOU if you are on dialysis; many recommendations may change based on your lab results.
People With a History of Kidney Stones
The best diet for someone with kidney stones is based on what the kidney stones they are forming are made of. Most kidney stones are made of calcium and oxalate. In general, a healthy kidney stone diet focuses on drinking lots of water (2-3 liters every day!), limiting how much sodium (salt) they eat, eating a moderate amount of protein and getting enough natural calcium (looking at you milk & yogurt!). For some people who continue to struggle with high oxalate in their urine despite eating adequate calcium, cutting back on some very high oxalate foods (spinach, almonds, rhubarb, miso) may be necessary.
I hope you find this very brief overview of the type of “kidney-friendly” diets helpful! Keep in touch with my blog to learn more about the specifics and tips for following each of these diets to help keep your kidneys as healthy as possible!
The National Kidney Foundation also has some great information about a healthy diet for Chronic Kidney Disease. Check it out here!
*”GFR” stands for Glomerular Filtration Rate. This number comes from blood labs your doctor takes. The number is roughly equivalent to what percentage your kidneys are working (i.e a GFR of 35ml/min tells us your kidneys are working at about 35% of what they should be). If you do not know what you GFR is, ask your doctor or dietitian!