Diet basics

Reading labels to control phosphorus in the dialysis diet

People with kidney failure have to be particularly careful about the foods they eat. Just like people with high blood pressure have to watch their sodium intake and people with diabetes need to control their carbohydrate intake, people with kidney disease, especially those on dialysis, need to monitor the amount of phosphorus in the foods they consume.

What is phosphorus?

Phosphorus is the second most common mineral in the body, after calcium. Phosphorus, also called phosphate, is absorbed in the small intestines, and about 85 percent of it is stored in the bones. It helps the body:

• use and store energy
• build strong bones and teeth
• maintain a normal pH balance
• activate enzymes and hormones
• build cell membranes

Nutritionists recommend that healthy adults with normal kidney function get between 700 mg and 1,200 mg of phosphorus each day. However, the average American diet contains much greater amounts of phosphorus.

According to the Food and Nutrition Board, over the last 20 years, phosphorus intake by Americans has increased significantly. Part of this increase is attributed to phosphorus-containing food additives in processed food, which people with kidney disease may want to avoid.

Extra phosphorus is removed by healthy kidneys, and levels start to rise with kidney disease even before a person needs dialysis. When kidneys fail, phosphorus can build up in the blood, a condition called hyperphosphatemia. This condition can cause a variety of toxic effects. A person can experience a wide range of problems such as teeth weakness, bone problems, joint pain or severe itching. High phosphorus levels may also contribute to heart disease, and can sometimes cause painful crystal deposits to form under the skin.

How much phosphorus does dialysis remove?

The amount of phosphorus removed in a dialysis treatment ranges from 250 to 1,000 mg per treatment. This number is affected by the pre-dialysis phosphorus level, the type of dialyzer and the amount of dialysis received. A good functioning dialysis access also makes a difference.

Because dialysis does not remove much phosphorus, it is important to stay on dialysis for the full treatment time. In addition, a low phosphorus diet and phosphorus binders are essential for most dialysis patients.

Foods high in phosphorus

Your dietitian will likely recommend that you limit or avoid foods that are high in phosphorus. Foods that naturally contain high phosphorus levels include milk and some milk products, bran, whole grains, brown rice, wild rice, dried beans and peas, nuts and seeds, organ meats, sardines, beer, corn tortillas and chocolate. Foods that contain high phosphorus due to phosphate additives include some types of baking powder, pancakes, waffles, biscuits, refrigerated bakery products, instant puddings and sauces, processed and enhanced meats, colas and many powdered, bottled or canned beverages.

While you may want to limit or avoid high phosphorus foods, there are alternative foods you can substitute for some of the most common high phosphorus foods that will dramatically lower the amount of phosphorus in your diet. Also, by choosing more unprocessed foods and preparing meals at home you have much greater control over the amount of phosphorus in your food. The following chart shows some high phosphorus foods and suggests some lower phosphorus foods which could be substituted.

High Phosphorus Foods	Phosphorus mg	Lower Phosphorus Alternatives	Phosphorus mg
½ cup milk	120 mg	½ cup rice milk or soy milk (unenriched)	30 – 60 mg (check label- brands differ)
½ cup ice cream	70 mg	½ cup sherbet or Italian ice	0 – 30 mg
1 cup raisin bran	200 mg	1 cup rice krispies	28 mg
2 tablespoons peanut butter	120 mg	2 tablespoons cream cheese	20 mg
1 ounce chocolate candy	60 mg	1 ounce Sweetarts®	0 mg
½ cup instant pudding	340 mg	½ cup Jello®	10 mg
12 ounces cola or Dr Pepper®	45 mg	12 ounces 7UP® or Sierra Mist®	0 mg
1 medium biscuit	202 mg	medium French roll	36 mg

Checking nutrition labels for hidden phosphorus

While many nutrients are listed on the nutrition labels of the foods you buy, it is not required by law for phosphorus to be listed on labels. Therefore, it is rarely listed in milligrams on the label. Some foods, such as cereals, list the % Daily Value for phosphorus. If milligrams or % Daily Value are listed, use the following as a guide to amount of phosphorus in foods:

• Low phosphorus           0-50 mg or less than 5% Daily Value
• Medium phosphorus     51-150 mg or 5-15% Daily Value
• High phosphorus            150 mg or higher or greater than15% Daily Value

If phosphorus is not listed on the nutrition label you can sometimes determine if a product contains phosphorus by reading the list of ingredients. You can spot hidden phosphorus by checking for variations of the word phosphate, such as phosphoric acid, sodium aluminum phosphate, pyrophosphate, polyphosphates and calcium phosphate. These words indicate high phosphorus content. You can also check the ingredient list for foods that you recognize as being high in phosphorus such as baking powder, cheese products or nonfat dry milk.

Remember to also check for phosphorus on the labels on any medicines and supplements you may take.

These days, more food manufacturers are including phosphates in their products than ever before. Phosphorus is used to prevent powder mixes from turning lumpy, to enhance or modify the flavor or texture of food and to extend the shelf life of food. Because phosphate use will likely continue, reading labels is a good habit to practice when food shopping.

Getting enough nutrition while limiting phosphorus

If you are a dialysis patient who has to limit phosphorus in your diet, it’s still possible for you to get the right amount of nutrition. The key is to select from the foods recommended on your eating plan and to pay attention to portion size. Some phosphorus containing foods, like meat, fish and eggs are required to provide adequate protein in the diet. Eating the right portions recommended by your renal dietitian helps keep phosphorus intake within your daily goal.

Your doctor and renal dietitian can help you create a diet high in the nutrients you need and low in the ones that could make you unhealthy.

The role of phosphate binders

Usually, for people with kidney failure, diet modifications alone won’t keep phosphorus levels in a safe zone. This is where phosphate binders can help. Phosphate binders decrease the absorption of phosphorus from food into the blood.

Phosphate binders help bind the phosphorus and remove the excess phosphate from the body through the gastrointestinal tract. This reduces the amount of phosphate that gets into the blood and helps keep your phosphorus level in a healthy range. Phosphorus binders should be taken as prescribed by your doctor or dietitian. Generally, it is recommended that phosphorus binders be taken immediately before or after meals or snacks. Your doctor and/or dietitian will tell you how many binders to take when you eat. It is recommended that you carry phosphorus binders with you so that you will have them handy if you are eating out.

Summary

While so many foods contain phosphorus, you can limit your phosphorus intake by making it a habit to read food labels and make low-phosphorus substitutions on your dialysis diet. Each month your phosphorus labs will show if you are doing well with your phosphorus control. Your renal dietitian can coach you and help plan meals that are low in phosphorus and fit your food preferences.

Related articles on DaVita.com

• Phosphorus and chronic kidney disease
• Common drugs prescribed for dialysis patients
• Potassium, phosphorus and the dialysis diet