Low Protein Diet
The low protein diet focuses on obtaining most of a person’s daily calories from complex carbohydrates rather than from proteins. There are two main sources of protein in the diet: higher levels are found in animal products, including fish, poultry, eggs, meat, and dairy products), while lower levels are found in vegetable products (breads, cereals, rice, pasta, and dried beans). Generally foods in the high protein food group contains about 8 grams of protein per serving. Cereals and grains have about 2 grams of protein in 1/2 cup or 1 slice. Vegetables have about 1 gram of protein in 1/2 cup, while fruits have only a trace amount of protein in 1/2 cup. To control protein intake, foods such as starches, sugars, grains, fruits, vegetables, fats, and oils should be eaten at levels sufficient to meet daily energy needs. If a person has diabetes, the diet must also be designed to control blood sugar.
Protein should never be completely eliminated from the diet. The amount of protein that can be included in the diet depends on the degree of kidney or liver damage and the amount of protein needed for an individual to maintain good health. Laboratory tests are used to determine the amount of protein and protein waste breakdown products in the blood. A suggested acceptable level of protein in a low-protein diet is about 0.6g/kg of body weight per day, or about 40 to 50 grams per day. A person suffering from a kidney disease such as nephrotic syndrome, where large amounts of protein is lost in the urine, should ingest moderate levels of protein (0.8 kg per kg of body weight per day).
A sample menu for one day might include:
Breakfast: 1 orange, 1 egg or egg substitute, 1/2 cup rice or creamed cereal, 1 slice whole wheat bread (toasted), 1/2 tablespoon margarine or butter, 1/2 cup whole milk, hot, non-caloric beverage, 1 tablespoon sugar (optional).
Lunch: 1 ounce sliced turkey breast, 1/2 cup steamed broccoli, 1 slice whole wheat bread, 1/2 tablespoon margarine or butter, 1 apple, 1/2 cup gelatin dessert, 1 cup grape juice, hot, non-caloric beverage, 1 tablespoon sugar (optional).
Mid-Afternoon Snack: 6 squares salt-free soda crackers, 1/2 tablespoon margarine or butter, 1 to 2 tablespoons jelly, 1/2 cup apple juice.
Dinner: 1/2 cup tomato juice, 1 ounce beef, 1 baked potato, 1 teaspoon margarine or butter (optional), 1/2 cup steamed spinach, 1 slice whole wheat bread, 1/3 cup sherbet, 4 apricot halves, hot, non-caloric beverage.
Evening Snack: 1 banana.
This sample menu contains about 1850 calories, with a protein content of 8%.
Special, low protein products, especially breads and pastas, are available from various food manufacturers for persons who need to follow a low protein diet. Specific information on the protein content of foods can be found on food labels. Books that list protein contents of various foods as well as low protein cookbooks are also available.
In addition, it is recommended that fat calories be obtained from monounsaturated and polyunsaturated fats. In order to be effective, some persons may also be required to reduce their sodium and potassium ingestion in foods. Sodium restriction improves the ability to control blood pressure and body fluid build-up as well as to avoid congestive heart failure. Foods with high sodium contents, such as processed, convenience and fast foods, salty snacks, and salty seasonings, should be avoided. Potassium is necessary for nerve and muscle health. Dietary potassium restriction is required if potassium is not excreted and builds to high levels in the blood, which may result in dangerous heart rhythms. At very high levels, potassium can even cause the heart to stop beating.
As kidney function decreases, the kidneys may reduce their production of urine, and the body can become overloaded with fluids. This fluid accumulation can result in swelling of legs, hands and face, high blood pressure, and shortness of breath. To relieve these symptoms, restriction of fluids, including water, soup, juice, milk, popsicles, and gelatin, should be incorporated into the low protein diet. Liver disease may also require dietary fluid restrictions.
Tyrosinemia is a rare but serious inherited disease that may also require the use of a low-protein diet. Tyrosinemia is an inborn error of metabolism in which the body can not effectively break down the amino acid tyrosine.
The purpose of a low protein diet is to prevent worsening of kidney or liver disease. The diet is effective because it decreases the stress on the kidney or liver.
Protein restriction lessens the protein load on the kidney or liver, which slows down the continued development of disease.
A person requiring a low protein diet should consult a dietitian familiar with liver or kidney diseases to provide guidance on developing an appropriate diet as well as to learn how to follow the diet effectively. The diet must meet the person’s nutritional needs, cut down the work load on the kidneys or liver, help maintain the kidney or liver function that is left, control the build-up of waste products, and reduce symptoms of the kidney or liver disease. Strict adherence to the diet can be difficult, especially for children. Small amounts of protein-containing food combined with larger amounts of low or no-protein foods can be used to make the diet more acceptable. Some persons eliminate meat, eggs, and cheese from their diets rather than measure the amounts of protein from these foods. However, care must be taken to make sure that adequate protein is included in a vegetarian diet to provide for growth and development, including building muscles and repairing wounds. Another approach, since it is difficult to manage portion sizes of foods other than milk, is to omit meats, fish, and chicken from the diet and use milk as the primary source of protein.
A person with both kidney disease and diabetes must be careful to eat only low-to-moderate amounts of carbohydrates along with monounsaturated and polyunsaturated fats.
The human body reacts to protein deficiency by taking amino acids (the building blocks of proteins) away from muscle tissue and other areas of the body. The process, in which the body basically metabolizes itself, is called catabolism and leads to muscle loss and weakness. The use of exercise and strength training is recommended to counter the effects of muscle loss.
The levels of calcium and phosphorus must be monitored closely, for in persons with kidney disease, phosphorus levels can become too high, while levels of calcium can become too low. Monitoring of these two minerals may require an adjustment in dietary intakes of these minerals. Phosphorus is a mineral that helps to keep bones strong. Too much phosphorus, however, may cause itchy skin or painful joints. Calcium is required to maintain bone density and vitamin D is necessary to control the balance of calcium and phosphorus. If changes to add these nutrients to the diet are not adequate, then supplements and medications may be required. If phosphorus levels are too high, a person may have to take phosphorus binders that reduce the amount of phosphorus that enters the blood stream from the intestine. Dairy products as well as seeds, nuts, dried peas, beans, and processed bran cereals, are high in phosphorus, so the use of these food sources may need to be limited.
A low protein diet may also be deficient in some of essential amino acids (which are the building blocks of protein), the vitamins niacin, thiamine, and riboflavin, and the mineral iron (most people with advanced kidney disease have severe anemia). Vitamin supplementation is dependent on the amount of protein restriction, the extent of kidney damage, and the vitamin content of food that is eaten. A person with kidney failure may have decreased urine output. The amount of fluids a person needs to drink is based on the amount of urine produced daily, the amount of fluid being retained, the amount of sodium in the diet, the use of diuretics, and whether the person has congestive heart failure.
In persons with advanced kidney disease, a low protein diet may lead to malnutrition. The person may lose muscle and weight, lack energy, and have difficulty fighting infections. Daily calorie intake is dependent on the amount needed to prevent breakdown of body tissues. Body weight and protein status should be monitored periodically, which in some cases may be daily. Extra calories can be added to the diet by increasing the use of heart-healthy fats, eating candy and other sweet foods, such as canned or frozen fruits in heavy syrup.
This material does not constitute medical advice. It is intended for informational purposes only.