With what seems like an endless number of potential diet plans to follow, it can feel overwhelming to discern what diet program is best for you. This is especially true for the estimated 10% of American adults who suffer from chronic kidney disease, or CKD. As with many chronic conditions, the renal diet is an important component of managing kidney disease; however, generalized or conventional dietary guidelines might be harmful if you suffer from kidney problems. If you feel lost when it comes to eating for healthy kidneys, the guidelines outlined in this article are a great place to start.
What Is the Renal Diet?
The renal diet was created to help minimize complications of chronic kidney disease and also prolong the healthy functioning of the kidneys. To better understand the reasoning behind the recommendations of the renal diet, it is important to first have a background knowledge of how the kidneys normally function and how kidney disease affects these processes.
Functions of Healthy Kidneys
The kidneys help manage several essential functions in the body, including:
- Filter bodily fluids to remove waste, toxins, and drugs/medications through urine
- Regulate or produce certain hormones
- Promote a balance of electrolytes and fluids in the body
- Regulate blood pressure
- Stimulate production of red blood cells
Chronic Kidney Disease
Chronic kidney disease, also called renal disease, involves damage to the kidneys resulting in the diminished ability to perform the above functions. This means that the body can no longer adequately remove substances such as toxins, fluids, or waste products from digestions like potassium and phosphorus from your bloodstream. It is believed that 31 million Americans suffer from chronic kidney disease.
Who Needs to Follow the Renal Diet?
Anyone diagnosed with chronic kidney disease can benefit from following the renal diet. If you are unsure, it is important to first speak with your healthcare provider or a Registered Dietitian. Doctors can use blood or urine tests to help detect kidney disease.
Risk Factors for Chronic Kidney Disease
The following are factors that may increase your risk of getting chronic kidney disease:
- Hypertension (high blood pressure)
- Family history of kidney disease
- Certain ethnicities (African Americans, Hispanics, Native Americans, and Asians are all at increased risk)
- Age (persons over 60 years old are more likely to develop chronic kidney disease)
- Heart disease
Signs/Symptoms of Chronic Kidney Disease
Kidney failure is progressive, meaning it usually gets gradually worse. Many people will not notice any symptoms in the early stages, so it is important to work with your doctor on a plan to monitor your kidney function, which can be done with a blood or urine test. As chronic kidney disease progresses into later stages, people may notice the following symptoms:
- Changes in urine output (either too much or not enough)
- Edema, or swelling, in the feet and ankles
- Shortness of breath
- Nausea, vomiting, or loss of appetite
- Muscle cramping
- Sleeping difficulties
Renal Diet: Foods, Recipes, and More
Renal failure involves a reduced ability to filter out waste products from our diet, so the renal diet was created to reduce the intake of substances that can be harmful if they accumulate in the body. This includes potassium, phosphorus, and sometimes fluids and protein. The renal diet is also low in sodium (salt) since lowering blood pressure can help protect the kidneys.
Lowering sodium, or salt, intake is an important component of most healthy diets; however, it can be especially important for people with kidney disease. This is because reduced salt intake can help lower blood pressure. Since high blood pressure is one of the leading causes of kidney disease, it is important to avoid this to help prevent further damage to the kidneys. The following foods are high in salt, and those on the renal diet should limit their intake of them:
- Processed meats including bacon, sausage, luncheon meat, pepperoni, bratwurst, hot dogs
- Canned foods, including soups or vegetables, except for those labeled "no salt added"
- Condiments like hot sauce, ketchup, barbecue sauce, soy sauce, gravy
- Salty snacks like salted nuts, pretzels, chips, certain cheeses, or crackers
Since some of the largest contributors to dietary sodium intake are processed foods and foods served in restaurants, it is helpful to prepare more foods from scratch at home if you're following the renal diet. Other low-sodium foods that can be part of the renal diet include:
- Fresh or frozen fruits and vegetables, or canned foods labeled "no salt added"
- Fresh meat
- Fresh dairy
- Salt-free seasonings and herbs like garlic powder, chili powder, oregano, lemon, cilantro, or vinegar
Potassium is a nutrient that helps regulate muscle contraction, including the muscles in our heart. With chronic kidney disease, the body cannot filter our potassium fast enough, which increases the risk for hyperkalemia, or build up of potassium in the blood. Consequences of abnormal potassium levels include muscle cramps, irregular heartbeat, or, in extreme cases, heart attacks. To prevent this, limit your potassium intake. It is important to talk with your doctor or dietitian first to find out what your blood potassium levels are and whether you need to follow a potassium restriction.
The following are high-potassium foods which you may need to cut down on while on the renal diet:
- Juices like orange juice, prune juice, tomato juice, and grapefruit juice
- Certain fruits including oranges, avocados, bananas, cantaloupe and honeydew melons, prunes, and raisins
- Some vegetables, such as potatoes, spinach, kale, tomatoes and tomato sauce, winter squash, and artichokes
- Dried beans of all kinds (kidney beans, black beans, pinto beans, etc.)
Lower potassium alternatives to the above foods that may be included as part of the renal diet include:
- Fruits: Grapes, strawberries, apples, peaches, pineapple
- Vegetables: lettuce, onions, peppers, cauliflower, radishes,
- Grains: white breads, white rice, tortillas, pita bread
Similar to potassium, phosphorus can build-up in the blood of people with chronic kidney disease and become too high. This is known as hyperphosphatemia, and can lead to a frail bone structure with high risk for bone fractures. It may also cause unwanted mineral deposits in the brain, lungs, eyes, etc. To prevent this, your doctor may suggest that you lower your phosphorus intake as part of the renal diet.
High phosphorus foods to limit include:
- Diary (milk, yogurt, cheese, ice cream)
- Certain whole grains like oatmeal, bran cereal, and whole-wheat bread
- Beer and dark-colored sodas (Coke, Pepsi, Root beer, etc.)
- Nuts and peanut butter
- Processed foods made with inorganic phosphorus as a preservative
Lower phosphorus options that may be safer while on the renal diet are:
- Milk substitutes like rice milk or almond milk, and nondairy creamer without phosphate additives
- White breads, white rice, or corn
- Lighter colored sodas like Sprite or 7 Up
- Unsalted popcorn or pretzels
Protein recommendations on the renal diet depend on how far the disease has progressed and whether you are on dialysis. You should consult your doctor or dietitian to help you determine the right amount of daily protein intake. As a general guideline, food sources of protein include:
- Meat products of all kinds
- Diary (milk, yogurt, cheese, etc.)
Since the kidneys play an important role in remove excess fluids from the body, your doctor may monitor your liquid intake while on the renal diet. If this is the case for you, keep in mind that fluids can come in many forms, including:
- Foods that melt like ice cream, gelatin, and ice
Finding the balance between sodium, potassium, phosphorus, fluids, and protein intake can feel overwhelming. Thankfully, there are many recipes online that are renal diet friendly. The following websites can serve as an excellent resource when deciding on meals to prepare:
Kidney disease is the ninth leading cause of death in the United States, but thankfully, we are learning more about how diet can help improve health outcomes for those suffering. Often, renal diet recommendations get tailored to each patient based on the progression of the disease, which is why it's so important to make dietary changes with guidance from your doctor or a Registered Dietitian.
If you know you have kidney disease, it is important to be mindful of your intake of sodium, potassium, phosphorus, and protein, as this helps manage the symptoms of kidney disease while also preserving the healthy functioning of your kidneys. If you think you may have kidney problems or are showing signs and symptoms of an issue with your kidney, speak with your healthcare provider right away.