Committing to better eating habits through diet and nutrition is important for your overall health. When you are diagnosed with Kidney Disease, making changes to your daily diet is a smart decision. Dietary intervention is one of the most important interventions in slowing down CKD progression.
The Importance of Diet in Kidney Disease
When your kidneys are not working properly they cannot get rid of waste products and extra fluids. Minerals in food eaten such as potassium, phosphorus, and sodium may also collect in your body which puts your heart, bones, lungs, and health at risk. The goal of the diet is to control your protein; potassium, phosphorus, calcium, sodium (salt), and fluid intake to help your dialysis treatments get rid of the waste products, minerals, and excess fluid. In addition, your diet must give you enough calories and protein to support a healthy body.
Limiting fluids, eating a low-protein diet, and limiting salt is a great start to a healthier you. In advanced stages of CKD, the kidneys can no longer remove excess potassium, resulting in an elevated level of potassium in the blood called hyperkalemia. To limit this increase, eating a diet of food with lower potassium levels can be required. Potassium is a mineral found in many of the foods you eat. It plays a role in keeping your heartbeat regular and your muscles working right. It is the job of healthy kidneys to keep the right amount of potassium in your body. The healthy kidney takes out waste products and extra minerals from foods eaten. It keeps sodium and water balanced. It supports normal bone health by balancing phosphorus and calcium.
Dietary Approaches to Stop Hypertension (DASH)
The DASH (Dietary Approaches to Stop Hypertension) Diet has been recommended by the National Kidney Foundation and approved by The National Heart, Lung and Blood Institute, The American Heart Association, the Dietary Guidelines for Americans, and also forms the basis for the USDA MyPyramid. DASH stands for Dietary Approaches to Stop Hypertension. The DASH diet is a lifelong approach to healthy eating that’s designed to help treat or prevent high blood pressure (hypertension). According to Fresenius Kidney Care the average American will consume 3,400 mg of sodium a day. The DASH Diet helps manage high blood pressure and kidney disease with fruits, veggies, whole grains, and low-fat dairy. Today’s leading health organizations are heartily endorsing the DASH Diet for the informed health-conscious diner.
What is the DASH Diet?
The DASH Diet is rich in fruits, vegetables, low-fat dairy products, whole grains, fish, poultry, beans, seeds, and nuts. It is low in salt and sodium, added sugars and sweets, fat and red meats.
Read also: Renal Diet Guide: Navigating Orange Juice Consumption
Who is the DASH Diet for?
The DASH diet is a recognized treatment for hypertension, heart disease, and kidney disease and can slow the progression of heart and kidney disease. If you already have chronic kidney disease, you should speak with your doctor and dietitian before starting any new diets as you may have special restrictions to consider. The DASH diet should not be used by people on dialysis. Individuals on dialysis have special dietary needs that should be discussed with a registered dietitian.
Example DASH diet for a 2,000 calorie diet
| Food Group | Daily Servings | Serving Size |
|---|---|---|
| Grains | 6-8 | 1 Slice bread 1 oz dry cereal 1/2 cup cooked rice, pasta, or cereal |
| Vegetables | 4-5 | 1 cup raw leafy vegetable 1/2 cup cut-up raw or cooked vegetable 1/2 cup vegetable juice |
| Fruits | 4-5 | 1 medium fruit 1/4 cup dried fruit 1/2 cup fresh, frozen, or canned fruit 1/2 cup fruit juice |
| Fat-free or low-fat milk | 2-3 | 1 oz milk or yogurt 1 1/2 oz cheese |
| Lean meats, poultry, and fish | 6 or less | 1 oz cooked meats, poultry, or fish 1 egg |
| Nuts, seeds, and legumes | 4-5 per week | 1/3 cup or 1 1/2 oz nuts 2 Tbsp peanut butter 2 Tbsp or 1/2 oz seeds 1/2 cup cooked legumes (dry beans and peas) |
| Fats and oils | 2-3 | 1 tsp soft margarine 1 tsp vegetable oil 1 Tbsp mayonnaise 2 Tbsp salad dressing |
| Sweets and added sugars | 5 or less | 1 Tbsp sugar 1 Tbsp jelly or jam 1/2 cup sorbet, gelatin 1 cup lemonade |
- Whole grains are recommended for most grain servings as a good source of fiber and nutrients.
- Serving sizes vary between 1/2 cup and 1 1/4 cups, depending on cereal type. Check the product's Nutrition Facts label.
The Phosphorus Pyramid: A Tool for Nutritional Education
Phosphorus retention plays a pivotal role in the onset of mineral and bone disorders (MBD) in chronic kidney disease (CKD). Phosphorus retention commonly occurs as a result of net intestinal absorption exceeding renal excretion or dialysis removal. Dietary phosphorus restriction is challenging, especially for those on dialysis needing a high-protein diet. It is vital to consider the amount of dietary phosphorus, its type (organic vs. inorganic), source (animal vs. plant), protein-to-phosphorus ratio, and bioavailability. Dietary education helps to reduce phosphorus intake while keeping adequate protein intake. Agreement exits regarding the need for dietary phosphate control, but it is quite challenging in the real-life setting. Effective strategies to control dietary phosphorus intake include restricting phosphorus-rich foods, preferring phosphorus sourced from plant origin, boiling as the preferred cooking procedure and avoiding foods with phosphorus-containing additives.
The phosphorus pyramid is herein proposed is an original, visual, user-friendly tool for nutritional education. It can support patients and caregivers in making the right food choices by encouraging adherence to dietary prescriptions, which is a crucial component for CKD-MBD. The Phosphorus Pyramid is a visual tool that was designed to present the phosphate load of various foods. The pyramid consists of six floors in which foods are arranged on the basis of phosphorus content, phosphorus to protein ratio and phosphorus bioavailability.
Understanding Phosphorus
As a natural food component, phosphorus is available as inorganic phosphate salts or as constituent of phosphoproteins, membrane phospholipids, ATP, ADP, DNA, RNA. The restriction of protein intake in non-dialysis CKD patients is generally associated with a lower phosphorus intake. The direct relationship between protein and phosphorus dietary content is well known: on average, a mixed diet contains 12-14 mg of phosphorus per gram of protein. During the “conservative” management of advanced CKD, the use of protein-restricted diets facilitates the reduction of dietary phosphorus intake. An analysis of phosphorus content (mg/100 g edible part) in the various food groups shows that the highest load comes from nuts, hard cheeses, egg yolk, meat, poultry and fish. Reporting the phosphorus content as mg per gram of protein (mg/g protein) is especially useful for identifying which foods supply less phosphorus with the same amount of protein.
Besides the absolute content, a crucial point is the net intestinal absorption of phosphorus. As previously mentioned, added phosphorus is almost completely absorbed: phosphoric acid is usually added to soft drinks (cola-drinks in particular). Boiling causes demineralization of food, thus reducing phosphorus as well as sodium, potassium, and calcium content in both vegetable and animal-derived products. The degree of mineral loss is proportional to the amount of boiling water that is used, the size of the pieces, the cooking time and the absence of the peel for plants.
Read also: Kidney-Friendly Cat Food Explained
Hidden Phosphorus
Phosphorus is the main component of several additives (phosphoric acid, phosphates and polyphosphates) used in industrial food processing to extend conservation, enhance color or flavor, and retain moisture. Food preservatives are added during the various stages of production, processing, preparation, packing, transport or storage. Current regulations require reporting the presence of phosphorus-containing additives on the food labels, but specifying the amounts is not required and is not available in most food composition databases. Such a high content may impair the effects and increase the costs of phosphate binder therapy which is expected to remove no more than 200-300 mg of phosphorus per day .
Renal patients need education and information about dietary sources of phosphorus and especially about the so-called hidden phosphorus. CKD patients are often unaware of artificially added phosphorus in food and drinks. Knowledge about phosphorus is overall lower than knowledge about other nutrients (namely sodium, potassium and proteins) as assessed by a 25-item CKD nutritional knowledge assessment tool (CKDKAT-N).
Levels of the Phosphorus Pyramid
Foods are distributed on six levels on the basis of their phosphorus content, phosphorus to protein ratio and phosphorus bioavailability. Each level has a colored edge (from green to red, through yellow and orange) that corresponds to recommended consumption frequency, which is the highest at the base (unrestricted intake) and the lowest at the top (avoid as much as possible).
- Level 1 (Green Edge): At the base of the pyramid, the first level (green edge) contains foods with very low phosphorus content (i.e., sugar, olive oil, protein-free foods) or very low bio-available phosphorus (i.e., fruit and vegetables). It also includes white-egg which has an extremely favorable phosphorus to protein ratio and is a source of proteins with high biological value and no cholesterol, all of which are issues of particular importance especially in dialysis patients. The intake of these foods is unrestricted. However, during counseling the operator should address special warnings to: diabetic patients, who should avoid sugar and not exceeding with fruit consumption ; overweight or obese patients, who should reduce sugar, olive oil, vegetables fats and butter intake; dialysis patients, who should limit fruits and vegetables consumption to avoid excessive potassium intake.
- Level 2: The second level mainly includes vegetable foods, richer in phosphorus but mainly as phytate, hence with less intestinal absorption: cereals (white bread, pasta, rice, cornflakes) or legumes (peas, broad beans, soy). A special warning regards farmed fish, as they are usually fed with flour and preparations rich in bioavailable phosphorus to promote rapid growth, resulting in sharply increasing the phosphorus content in the edible parts.
- Level 3: Milk and yogurt are also in this section: they have high phosphorus content but one portion a day does not significantly influence the total amount of dietary phosphorus.
- Level 4: The fourth level shows foods with higher phosphorus to protein ratio. These include various products such as turkey, offal (liver, brain) and shrimp, squid, salmon, and soft cheeses.
- Level 5: The fifth level contains foods with very high phosphorus content such as nuts, yolk and hard cheeses.
- Level 6 (Red Edge): Processed foods with phosphorus-containing additives include colas, processed meat, and processed cheese. The boiling pot on the left side suggests boiling as the best cooking method to reduce the phosphorus content.
Additional Dietary Considerations for Kidney Disease
Protein
Protein is well known for its ability to build and repair body tissue. Adequate protein intake can help keep your immune system strong to defend your body against infections. However, when your body breaks down protein it produces waste products that build up in the blood and become harmful to the body.
Eating a low protein diet before starting dialysis may help keep some kidney function and delay the start of dialysis. Your doctor will determine whether a low protein diet is good for you and refer you to a dietitian who can help plan your diet.
Read also: Comprehensive Guide to Renal Diet Meals
Once dialysis is started, protein and calorie needs are greater. Protein needs are increased but still need to be controlled. Not enough protein can cause muscle breakdown, weakness, and increase your chance of infection. Too much protein can create unpleasant symptoms such as nausea, vomiting, fatigue, and taste changes. Protein foods have high amounts of potassium and phosphorus, which are minerals that can remain in the body and reach dangerous levels. Your doctor and dietitian will decide your special protein needs and watch your laboratory values to adjust your diet as needed.
High quality protein foods (from soy and animal protein: chicken, fish, beef, eggs, dairy) are better absorbed by the body when compared to poor quality protein (from plant foods: bread, vegetable, beans). To keep protein for it’s essential functions adequate calories must be eaten. You may achieve the best protein intake when you spread out your protein foods throughout the day instead of at just one or two meals.
Potassium
Potassium is a mineral that is required by the body for nerve and muscle activity. It is found in all types of foods including meat, dairy products, dried beans, and is especially high in fruits and vegetables. When your kidneys no longer can filter extra potassium out of the body, it begins to build up in the blood endangering your heart muscle. Serious complications can occur with too much potassium in the body such as muscle breakdown, irregular heartbeat, and cardiac problems. Potassium levels can become too low and you may have muscle weakness, shakiness, and tingling feelings. You must maintain a good potassium level in the blood.
Portion control (the amount of a food that you eat at one time) is essential in limiting the potassium content you eat. You may also learn ways to decrease the potassium in foods such as buying low sodium/sugar canned fruits and vegetables instead of fresh. Your dietician can also teach you how to double boil certain vegetables such as potatoes to lower the potassium content.
Phosphorus and Calcium Balance
Your body likes to keep a balance between the two minerals - phosphorus and calcium - which are needed for bone health. A healthy kidney plays an important role in this balance by changing vitamin D to the active form, which helps the body to absorb more calcium if needed. In kidney disease, the phosphorus in many foods may build up in the blood and upset this balance causing a decrease in blood calcium. Eat a low phosphorus diet. Avoiding high phosphorus foods such as excess dairy foods - milk, cheese, yogurt, nuts/seeds, chocolate, beans, and bran. In addition avoiding foods that have phosphorus additives (hidden phosphorus) such as colas, muffin and pancake mix, processed meats - hotdogs, sausage, lunch meats, fast foods, and many processed and convenience foods.
Good protein foods that you need to eat are often high in natural phosphorus therefore your doctor will prescribe a phosphorus binder for you to take with your meals and snacks. Phosphorus binders do exactly what the name says, they bind with phosphorus in foods since your body can no longer get rid of this excess phosphorus. There are many different types of phosphorus binders that are available as pills, chewable tablets, liquids, and powders that can be mixed in beverages. Take your phosphorus binders when you eat meals or snacks that contain phosphorus foods. Your dietitian will teach you how to adjust your phosphorus binders for the amount of phosphorus at your meals and snacks to achieve the most binding power.
Sodium and Fluid Balance
One of the important functions of the healthy kidney is its ability to regulate sodium (salt) and water (fluid) balance. The kidneys will keep sodium or fluids if body amounts become too low. They will rid the body of extra fluids or salt to keep the body’s proper balance. When your kidneys are not working sodium and water are not in balance. High salt intake can start the body's thirst reaction, which will lead you to drink more water. In kidney disease this natural response to drink more may cause your body to swell and gain weight, often called edema. Reducing your intake of high salt foods and controlling your water intake is essential.
You will need to reduce your intake of high salt foods such as canned foods, frozen dinners, olives, soy sauce, deli-style lunch meats, cheese, canned soups, and packaged food items. Talk to your dietitian to learn which foods you’ll need to reduce and how to read food labels for salt content. Keep track of the fluids you drink and remember to count any food item that melts at room temperature such as sherbet, Jell-O, and ice cubes. Drain all liquids from canned fruits and low salt vegetables. Count on water as being a true thirst quencher instead of sodas or sugar-containing drinks.
Making Dietary Changes and Maintaining a Healthy Appetite
Making changes in your eating habits is not easy. You may feel frustrated, overwhelmed, and angry. It is even scary to change old familiar habits for new ones. Recognize that your feelings of frustration, fear, and/or anger are normal. Try to develop motivational factors to help you approach the changes.
People new to dialysis often complain of a poor appetite. This may be explained in part by recent hospitalization and illness. Emotional feelings prior to and when starting dialysis can also affect one’s appetite. The build up of waste products can cause taste changes, nausea, and vomiting and will affect the desire to eat. Remember it is important to discuss any appetite changes with your dietitian who can give you specific suggestions based on your own needs. Remember the effect that good nutrition has on your general health. Make smaller portions of food mean something. Raise the calories by adding nutrient dense sugar and fat to your food. Your dietitian or doctor may recommend a nutrition drink or supplement. Have already prepared foods and snacks on hand.
Heart Health and Cholesterol
Heart disease is a serious concern for the kidney patient. In addition to replacing folic acid, a water -soluble vitamin that can be depleted during dialysis, a low cholesterol and saturated fat diet may help prevent this disease. However, whether it is appropriate for you to follow a low cholesterol, low saturated fat diet is dependent on many factors including your doctor’s recommendations, current and past medical history, willingness to make additional changes, and your nutritional status.
Fat is an important calorie source for you. Starting a low cholesterol and low saturated fat diet may cause weight loss if calories are not replaced by other sources. Weight loss may or may not be beneficial depending on your nutritional status. A cholesterol restriction may not be appropriate for an elderly or malnourished patient when it is crucial that adequate nutrition is achieved and/or maintained. Replace unhealthy saturated fats with heart healthy monounsaturated fats found in canola and olive oils. Polyunsaturated fats such as safflower, sunflower, and corn oil may also be used. In addition, omega 3 fatty acids found in fatty fish such as salmon and mackerel may be eaten.
Diabetes and Kidney Disease
Many people with diabetes have been taught to eat more foods with fiber, to limit protein intake, and limit total fat intake. These recommendations were fine before kidney disease was found; some changes may need to be made by those on hemodialysis. Foods high in fiber such as fruits, vegetables, beans, and bran/whole grains need to be limited or avoided because of their high potassium and phosphorus content. Protein needs are often higher because of losses that occur during the dialysis procedure. In some people with kidney disease, fat may become an important calorie source that helps fight weight loss.
Maintaining carbohydrate intake at meals (often difficult with a poor intake) is essential if insulin is used. If a person with kidney disease and diabetes is not eating sufficient calories and carbohydrates then sugar may be beneficial. Talk to your dietitian before adding additional sugar.
Regular meals, snacks eaten at the same time, use of the same kind and amount of food is useful to regulate blood sugar levels, especially if insulin is used. People with diabetes are often taught to grab some orange juice when a low blood sugar reaction occurs. Most people with kidney disease must limit or avoid orange juice because of the potassium content and must learn appropriate food items to consume during a low blood sugar reaction.
The Role of the Kidney Care Team
Your kidney care team will guide you to make the right food choices based on your needs after. Assessment and control of dietary phosphorus intake is a complex, difficult task. In any case, a multidisciplinary approach is required. How the dietitian interacts with the patients is as important as the dietary prescription: an understanding and non judging relationship is crucial for the patient to successfully adhere to the suggestions, thus sustaining the efforts to change habits in order to fulfill the dietary prescriptions .