Renal Diet: Proven Foods for Healthy Kidneys & Foods You Must Avoid (Science Based)

Kidney Cleanse: The Best Foods and Herbs

The renal diet includes kidney-friendly foods that can be beneficial if you suffer from chronic kidney disease (CKD). Foods such as fruits and vegetables, fish, and small portions of lean meat are foods that are good for the kidneys. To help care for your kidney health if you have CKD, it is also important to avoid foods that are high in sodium, potassium, and phosphorus.

Chronic kidney disease impairs the kidneys’ function to remove salts and minerals from the body. Therefore, it is essential that a renal diet (or, kidney-friendly diet) is one that promotes good kidney health. This can also slow down the progression of CKD and help you lead a better, more fulfilling life.

In this article, you will learn about what foods to avoid with kidney disease. You will also find out about healthy food choices on the renal diet that are good for your kidneys.

The Connection Between Renal Diet and Kidney Disease

Your kidneys are bean-shaped organs that help to filter blood, remove waste, balance minerals, and maintain fluid balance.

If you have CKD or renal disease, it is essential to consume foods that boost kidney health.

The journal Nutrients reported that switching to a kidney-friendly diet can protect the kidneys from further damage. If you have chronic kidney disease, consuming foods that are good for the kidneys can prevent an accumulation of minerals in the body that could lead to further complications. (1)

One cohort study found that a renal diet that includes foods to avoid with kidney disease improved symptoms of CKD. Switching to a healthy kidney diet helped to improve outcomes of CKD by nearly 20%. (2)

The Journal of Nephropharmacology reports that a renal diet should limit sodium and potassium intake to no more than 2 grams per day. The limit for phosphorus on a renal diet menu is up to 800 mg per day. (3)

The renal diet also includes dietary restrictions depending on the stage of the kidney disease. For example, a chronic kidney disease stage 3 diet restricts protein to 0.8 g per kg of body weight. This is because protein can affect the filtration efficiency of the kidneys and aggravate CKD. (4)

However, in serious cases of kidney disease where hemodialysis is necessary, protein intake is increased in the kidney diet. (5)

What Is the Renal Diet?

The renal diet menu includes foods that are known to be good for the kidneys and avoids foods associated with kidney disease. The renal diet should also be adapted to a person’s dietary needs depending on their stage of chronic kidney disease.

In general, the renal diet restricts foods that are high in sodium, potassium, and phosphorus.

Let’s look briefly at the effects of these minerals on kidney function in cases of CKD.

Sodium effects on the renal diet

The kidney-friendly diet restricts sodium because too much salt increases blood pressure, levels of protein in urine (proteinuria), and can aggravate CKD.

The journal Seminars in Dialysis reports that on average, people tend to consume more sodium than the recommended daily limit of 2.3 grams per day. However, a renal diet should restrict salty foods because they increase proteinuria and limit the benefits of other therapies. (6)

Even healthy people should limit their use of sodium in the diet, because hypertension due to sodium increases the risk of CKD. (6)

The National Kidney Foundation says that many processed foods, convenience foods, cured foods, and salted snacks contain high levels of sodium. Checking label packaging and using low-sodium alternatives in cooking can help monitor your sodium intake. (7)

Effects of potassium on the renal diet

Potassium is a mineral that is essential for a healthy heart and proper muscle function. However, a kidney-friendly diet restricts potassium-rich foods as impaired kidney function can lead to too much potassium in your body – hyperkalemia.

The journal Nutrients reports that in early stages of chronic kidney disease, it may not be necessary to limit the intake of potassium-rich foods in a renal diet. Foods rich in potassium can improve cardiovascular health and improve the symptoms of CKD. (8)

However, in cases of advanced CKD, doctors recommend limiting potassium to no more than 3 grams per day to prevent hyperkalemia. (8)

As well as avoiding too much potassium on a low kidney function diet, researchers warn that advising intermittent hemodialysis patients to limit or avoid many potassium rich plant-based foods, especially fruits and vegetables, may affect negatively on their health and may contribute to conditions such as constipation or hypertension. (9)

However, the researchers agreed that due to lack of conclusive data and until further studies are conducted, doctors should continue to advise restriction of high-potassium foods. (9)

How phosphorus affects the renal diet

Phosphorus is an essential mineral that is prevalent in protein-rich foods. Scientific research points to the fact that too much phosphorus could affect renal function and aggravate CKD symptoms.

A 2017 review reported that the reason why foods high in phosphorus are limited on the renal failure diet is that kidney disease restricts excess phosphorus excretion. Too much phosphorus can lead to a calcium buildup and affect bone health, lung function, and cardiovascular health. (10)

Protein intake in the renal diet

In the later stages of CKD, protein is often restricted in a kidney-friendly diet because phosphorus is found in protein-rich foods.

The journal Kidney International Reports in 2018 published a review on many studies on the effect of protein in chronic kidney disease. Many studies point to the fact that a low-protein diet can slow the progression of chronic kidney disease. However, a diet that restricts protein can also lead to malnutrition and other complications. Therefore, the review concluded that dietary counseling and reasonable protein intake reduction is necessary to preserve kidney function in CKD patients. (11)

Foods Low in Potassium to Eat as Part of the Renal Diet

A kidney-disease diet should include low-potassium foods so as to limit potassium intake to less than 3 grams a day. However, if you have no risk of hyperkalemia, then scientists say that you could take up to 4.7 grams per day. (8)

Low potassium fruits that are good for your kidneys

Here are some fruits that are low in potassium per portion (1/2 cup), unless otherwise noted, and can be added to a renal diet. (23) Eating more than 1 portion can make a lower potassium food into a higher potassium food.

  • A medium apple with the skin on contains 195 mg of potassium which is 6% of your recommended daily intake (RDI) on a normal diet. However, if you eat an apple without the skin, there is only 145 mg of potassium in it. (9, 10)
  • A small pear contains 172 mg of potassium. (11)
  • Half a grapefruit contains 166 mg of potassium. (12) Please note that grapefruit can interact with some common medications so consult with your doctor if you are not sure about its impact on the drugs you take.
  • 1 medium Orange (1 medium) has 237 mg of potassium. (13)

Other low-potassium fruits that are good choices on a kidney-friendly diet include 1 whole plum (100 g has 157 mg of potassium) (15), 1 small peach (190 mg of potassium per 100 g) (16), 1/2 cup pineapples (109 mg of potassium per 100 g) (17), and 1 cup watermelons (112 mg of potassium per 100 g). (18)

Low potassium vegetables that are good for your kidneys

Vegetables are essential on a chronic kidney disease diet because they contain important nutrients and fiber. However, you should know which vegetables are good on a renal diet.

Here are some vegetables that are low in potassium per portion (1/2 cup), unless otherwise noted. (23) Eating more than 1 portion can make a lower potassium food into a higher potassium food.

  • 1/2 cup of cooked cabbage. (19, 20)
  • 1/2 cup of cauliflower. You can lower its potassium content by boiling the vegetable. (21, 22)

Other fruits that are low in potassium per portion and are kidney-friendly on a renal diet include 1/2 cup cooked carrots (25), 1 stalk celery (26), 1/2 cup green peas (27), and 1/2 cup onions (146 mg of potassium per 100 g). (28)

It is good to remember that blanching or cooking vegetables in plenty of water generally reduces their potassium content.

Other low-potassium foods that are good for kidney disease

Other foods per portion that you can include on a renal diet include white bread, pasta, and rice. (23)

Foods High in Potassium to Avoid in the Renal Diet

If you have chronic kidney disease, especially in the later stages, it is important to limit high-potassium foods.

Fruits with high potassium levels to avoid on the chronic kidney disease (CKD) diet

Let’s look at some of the high-potassium fruits (portion size is ½ cup unless otherwise stated) that you should leave out from a renal diet. (23)

  • 1/2 whole banana. (29)
  • 1 whole pomegranate. (30, 31)
  • 1 medium mango. (32)

Other fruits that should be avoided on a kidney-friendly diet because of their potassium content per portion include dried fruits (some dried fruits can have up to 996 mg potassium for 100 g!) (33), honeydew melons (34), 1 medium kiwifruit (35).

Other high potassium foods to avoid on a renal diet

  • 1/4 whole avocado. (36)
  • Beets. (37)
  • Baked beans. (38)
  • White and sweet potatoes. (39, 40)
  • Tomatoes. (41)

Other high-potassium foods per portion that you should be careful of if you have kidney disease are 1 cup milk, Brussels sprouts, parsnips, pumpkin, and cooked spinach. (23)

Foods Low in Sodium that are Good for the Kidneys

One of the most important aspects of following a renal diet for kidney health is to avoid sodium-rich foods. Salty foods are definitely some of the most important foods to avoid on a kidney-friendly diet.

In general, fresh fruits and vegetables are naturally low in sodium. If you prepare your own food from scratch on a CKD diet, you can easily control the sodium content of food.

To make foods for kidney health tasty and appetizing, you can add various spices and herbs to improve their flavor.

According to the National Kidney Foundation, food substitutes to make food tastier include garlic, black pepper, lemon juice, and onions. (7)

Foods High in Sodium that are Bad for the Kidneys

If you have to follow a low-kidney function diet because of health complications, you should avoid adding salt to your food.

What are some of the sodium-laden foods to avoid with kidney disease?

High sodium foods to avoid on a renal diet

Any kind of processed food can have varying amounts of salt. Therefore, the National Institute of Diabetes and Digestive and Kidney Diseases recommends carefully checking food labeling for sodium content. (42)

Some of the foods that are generally avoided because of their high sodium content include the following: (7)

  • Convenience foods. Many fast foods, prepared meals, commercial mixes, pizzas, and canned sauces contain high sodium levels.
  • Processed foods. You should also check the food labeling on canned soups, pizza sauces, vegetable juices, broths, and canned vegetables.
  • Dairy products. Cheese can contain surprisingly high levels of sodium which is not good if you have kidney disease.
  • Cured foods. Salt is used in the curing process of many foods. Foods to avoid with kidney disease include bacon, sauerkraut, ham, pickles, and olives.
  • Other high-sodium foods. If you have CKD, then it is good to stay away from foods like hot dogs, soy sauce, bottled salad dressings, and salted butter.

The good news is that there are plenty of healthy alternatives to sodium-rich foods. For example, you can look for low-sodium options. If you used canned vegetables, rinse the vegetables through before using them.

Foods Low in Phosphorus that Are Good for the Kidneys as Part of the Renal Diet

Your doctor may advise you to choose low-phosphorus foods for your kidney-friendly diet. If you have low kidney function, even relatively low levels of phosphorus can build up in your body and have a negative impact on your health.

Most plant-based foods contain some amount of phosphorus. Phosphorus is also present in protein in many animal foods. According to the National Kidney Foundation, phosphorus from plant proteins is not absorbed as much as animal-based protein sources. (45)

Doctors from the Mayo Clinic say that some types of food that are low in phosphorus include lean meat, eggs, poultry, low-fat dairy products, and homemade meals. (46)

Foods High in Phosphorus to Avoid as Part of the Renal Diet

If you are looking for foods to avoid with kidney disease, then it’s important to know where phosphorus can be lurking in your food.

The International Journal of Nephrology says that 1 gram of protein contains 13-15 mg of phosphate. From this, between 30 and 70% is absorbed during the digestion process. (47)

According to the National Kidney Foundation, some phosphorus-rich foods include beef or chicken liver, dairy products, beer, and colas. (45)

The foods to avoid if you have kidney disease are processed foods where phosphorus is added. Phosphorus as a food additive is completely absorbed in the body. (45)

Researchers say that if you have chronic kidney disease, you should avoid processed foods that contain phosphorus additives. In fact, foods containing added phosphorus may have up to 60% more phosphorus than similar-type foods without the additive. (48)

Some foods that may be bad for your kidneys because of added phosphorus include fast foods, convenience foods, processed cheeses, processed meats, and canned sodas. (46)

Most research studies on chronic kidney disease (CKD) recommend carefully reading the packaging on food labels to avoid phosphorus-rich foods. Medical studies about CKD also recommend to cook meals from scratch as much as possible. (48)

To know what look for, check for any additive with the root word “phos” in it. Some examples are phosphoric acid, diphosphates, polyphosphates, and phosphates.

Eat Lower Protein Foods as Part of the Renal Diet

A renal diet menu for advanced kidney disease usually involves limiting protein-rich foods.

Studies have shown that one of the reasons to eat lower protein foods to preserve kidney health is that the kidneys metabolize amino acids. A high-protein diet should be avoided with kidney disease as it can lead to an accumulation of toxins. This puts extra strain on the kidneys and can aggravate chronic kidney disease. (49)

However, medical researchers say that restriction of protein in cases of kidney disease should be closely monitored by a doctor or dietitian. This is necessary to help prevent complications of malnutrition.

Renal Diet: The Bottom Line

Choosing which foods to include on the renal diet to preserve kidney health generally involves limiting sodium, potassium, and phosphorus.

Most natural foods that are unprocessed are naturally low in sodium and don’t contain significant amounts of phosphorus (apart from organ meats and some dairy products).

Even with foods that contain significant amounts of potassium, portion size can help you keep your potassium levels below the recommended amount for kidney disease.

However, the foods to avoid for kidney disease and the foods to include on a renal diet greatly depend on your kidney function and severity of the disease.

Foods on the renal diet menu can help to preserve the health of your kidneys and may slow down the progression of CKD.

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