SODIUM-CONTROLLED DIET

Description
The Sodium-Controlled Diet limits sodium intake to a prescribed level determined by the requirements of a specific disease state.  Foods and condiments high in sodium are eliminated or restricted.

    The average dietary sodium intake is approximately 4,100 mg/day for American men and 2,750 mg/day for American women; the consumption of processed foods accounts for 75% of the daily sodium intake (1).  The minimum daily sodium requirement for healthy adults is estimated to be 500 mg (2).  The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressureand the National Research Council recommend that the daily intake of sodium be limited to 2,400 mg (1,2).  This recommendation provides guidelines for menu planning and offers direction for preparing healthful alternatives.

Indications
The Sodium-Controlled Diet is used in the treatment of conditions characterized by edema (water retention), including the following:

• cirrhosis of the liver with ascites
• congestive heart failure
• hypertension
• renal disease

    Under normal physiologic conditions, the body responds to an increase in sodium consumption with an increase in sodium excretion, generally eliminating the excess sodium within 24 hours (2,3).  However, certain diseases or conditions impair the body’s ability to maintain a normal sodium and water balance, necessitating a reduction in sodium intake.  Excess sodium in the body caused by one of the conditions listed above can lead to edema, increased blood pressure, thirst, and shortness of breath.

    Cirrhosis of the liver with ascites: Ascites, an accumulation of nutrient-rich fluid in the peritoneal cavity, often occurs as a result of hepatic cirrhosis.  A small percentage of patients with this condition lose weight and reduce their fluid volume by adhering to a sodium-controlled diet (4).  Almost 90% of patients respond to combination therapy consisting of a sodium-controlled diet and diuretics, whereas the other 10% of patients are resistant to combination therapy and require further medical intervention (5).  Although fluid restrictions often accompany sodium-controlled diets, the efficacy of this practice in the treatment of patients with ascites has been challenged.  Fluid restriction may not be necessary unless the serum sodium level drops below 120 mEq/L (4).  In patients with ascites, the treatment goal is to achieve a negative sodium balance and a weight loss of 0.5 kg/day (4).  Sodium-controlled diets that provide 500 to 2,000 mg of sodium per day, depending on the patient’s fluid volume, are recommended (4).

    Congestive heart failure: In patients with congestive heart failure, the kidneys respond to a decrease in systemic blood flow by increasing the absorption of sodium and fluids, leading to edema and worsening heart failure.  To promote diuresis, a sodium-controlled diet accompanied by diuretic use is the preferred method of treatment (1,2).  A 2,000-mg sodium diet is sufficient for patients to respond to diuretic therapy.  National clinical practice guidelines for mild to moderate congestive heart failure suggest limiting sodium to 2,000 mg/day and to not exceed 3,000 mg/day (6).  (See Clinical Nutrition Management of Heart Failure.)

    Hypertension: Sodium-sensitive individuals have an impaired ability to excrete large concentrations of sodium, leading to increased serum sodium levels, hypervolemia, and hypertension.  Between 20% and 50% of individuals with hypertension, particularly the elderly and African Americans, respond to an increase in sodium consumption with an increase in blood pressure (3).  The most recent guidelines from the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommend that patients with stage 1 and stage 2 hypertension be treated with a 2,400-mg (100-mmol) or less sodium-controlled diet accompanied by other lifestyle modifications.  These lifestyle modifications include losing excess body weight, following the Dietary Approaches to Stopping Hypertension (DASH) eating plan, increasing physical activity, and avoiding excess alcohol intake (1).  The DASH collaborative intervention studies have demonstrated that a reduced sodium diet (<2,400 mg/day) that includes increased intakes of fruits, vegetables, potassium-rich foods, and low-fat dairy foods and decreased intakes of total fat (27%), saturated fat (6%), and cholesterol (<150 mg) has a significant effect on lowering blood pressure (7,8).  Patients who followed the DASH eating plan experienced an 8- to 14-mm Hg reduction in systolic blood pressure (7,9).  The greatest blood pressure reductions were observed in patients who followed the DASH eating plan at a sodium intake level of 1,500 mg/day (7,9). Sodium-controlled diets also enhance the effectiveness of diuretic therapy (1,2) and may help individuals remain normotensive after the cessation of pharmacologic therapy (1,10).

    If a potassium-wasting diuretic, such as thiazide or a loop diuretic, is prescribed, a diet containing increased amounts of potassium may be necessary to avoid hypokalemia (2).  (See Nutrition Management of Potassium Intake later in this section and Hypertension and DASH Eating Plan.) 

    Renal disease:See Medical Nutrition Therapy for Chronic Kidney Disease.

Contraindications
Under normal conditions, the dietary restriction of sodium intake should not cause sodium depletion. However, a sodium-controlled diet is contraindicated in the presence of the following:

• conditions that promote sodium depletion (profuse perspiration, vomiting, and diarrhea)
• impaired mechanisms of sodium conservation (colectomy and ileostomy in the postoperative period)
• conditions that conserve sodium as a normal physiologic adjustment (pregnancy)
• lithium carbonate therapy*

    *The kidney does not always discriminate between sodium and lithium.  Therefore, with a low sodium intake, the kidney may conserve both sodium and lithium, causing an elevated serum lithium level and the potential for lithium toxicity (3).

Nutritional Adequacy
Sodium-controlled diets can be planned to meet the Dietary Reference Intakes as outlined in the Statement on Nutritional Adequacy.

How to Order the Diet

• Order the diet in terms of sodium, not salt.
• Order the amount of sodium that should not be exceeded in the diet. Different levels of sodium-controlled diets limit the daily sodium intake to 2,000 mg (87 mEq), 3,000 mg (130 mEq), or 4,000 mg (174 mEq).
• The dietitian may allow certain higher sodium foods to be added to the patient’s diet if the patient’s sodium intake falls below the prescribed range due to low energy intake.

Note: Diets containing less than 2,000 mg of sodium per day are difficult to sustain outside of the hospital environment for reasons of palatability and convenience (2, 6).

Planning the Diet
Salt substitutes:Salt substitutes will not be offered unless a physician, standing order, or an organization’s policy designates their use.  Salt substitutes may contain potassium chloride, which could be contraindicated under certain conditions.  Some salt substitutes also contain various amounts of sodium.

    Sodium in medications: Patients on a sodium-restricted diet should be made aware that certain over-the-counter medications (eg, seltzers and some antacids) contain high quantities of sodium and that they should consult their physician if the medications are used on a regular basis. 

 References

1. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, Jones DW, Materson BJ, Oparil S, Wright JT Jr, Roccella EJ, and the National High Blood Pressure Education Program Coordinating Committee.  Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.  Hypertension.  2003;42:1206-1252.
2. Whitmere S. Water, electrolytes, and acid-base balance. In Mahan KL, Escott-Stump S. Krause’s Food, Nutrition and Diet Therapy. 10th  ed. Philadelphia, Pa: WB Saunders; 2000;159.
3. Haddy FJ, Pamnani MB. Role of dietary sodium in hypertension. J Am Coll Nutr. 1995;14:428-438.
4. Runyon BA. Care of patients with ascites. N Engl J Med. 1994;330:337-342.
5. Aiza I, Perez GO, Schiff ER.  Management of ascites in patients with chronic liver disease.  Am J Gastroenterol.  1994;89:1949-1956.
6. Konstam MA, Dracup K, Bottorff MB, Brook H, Dacey RA, Dunbar SB, Jackson AB, Jessup M, Johnson JC, Jones RH, Luchi RJ, Massie  M, Pitt B, Rose EA, Rubin LJ, Wright RF, Baker DW, Born DC. Heart Failure: Evaluation and Care of Patients With Left Ventricular Systolic Dysfunction. Clinical Practice Guideline No. 11. Rockville, Md: Agency for Health Care Policy and Research, Public Health Service, US Department of Health and Human Services; 1994. AHCPR Publication No. 94D617.
7. Sacks FM, Svetkey LP, Vollmer WM, Obarzanek E, Conlin PR, Miller ER 3rd, Simons-Morton DG, Karanja N, Lin PH.  DASH-Sodium Collaborative Research Group.  Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet.  N Engl J Med.  2001;344:3-10.
8. Svetkey LP, Simons-Morton D, Vollmer WM, Appel LJ, Conlin PR, Ryan DH, Ard J, Kennedy BM, for the DASH Research Group. Effects of dietary patterns on blood pressure: subgroup analysis of the Dietary Approaches to Stop Hypertension (DASH) randomized clinical trial.  Arch Intern Med.  1999;159:285-293.
9. Vollmer WM, Sacks FM, Ard J, Appel LJ, Bray GA, Simons-Morton DG, Conlin PR, Svetkey LP, Erlinger TP, Moore TJ, Karanja N. Effects of diet and sodium intake on blood pressure: subgroup analysis of the DASH-sodium trial.  Ann Intern Med.  2001;135:1019-1028.
10. Alderman MH. Non-pharmacological treatment of hypertension. Lancet. 1994;344:307-311.

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