LOW SODIUM DIET OVERVIEW

Sodium is an element that is found in many foods as well as water. The body requires a small amount of sodium in the diet to control blood pressure and blood volume. However, most people consume many times the amount of sodium needed. A low sodium diet contains fewer than 2 grams (2,000 milligrams) of sodium each day. People with certain medical conditions such as high blood pressure, kidney disease, and heart problems can benefit from a diet that is low in sodium.

This topic will review how to read food labels, how to choose foods that are low in sodium, and how to live with less salt.

WHY SHOULD I REDUCE SODIUM IN MY DIET?

Reducing sodium intake lowers blood pressure in people with high and borderline high blood pressure. Reducing sodium can also help to prevent the collection of fluid in the lower legs or abdomen. People with chronic kidney disease must control sodium intake to prevent volume overload, which increases blood pressure and causes swelling. (See "Patient information: Chronic kidney disease".)

Decreasing sodium can also assist people who have heart failure. (See "Patient information: Heart failure".)

Switching from a higher sodium diet to a lower sodium diet can modestly reduce blood pressure in people who have normal blood pressure. When the sodium intake is lowered from 4000 mg to 2000 mg per day, blood pressure falls by 2 to 3 mmHg. This reduction may be as great as 10 mmHg over several years and can substantially lower the risk of heart disease.

Benefits — In addition to directly reducing blood pressure, a lower sodium intake may also enhance the effectiveness of high blood pressure medications and other non-drug treatments, such as weight loss. A lower sodium intake has also been associated with other health benefits, including a reduced risk of dying from a stroke, reversal of heart enlargement, and a reduced risk of kidney stones and osteoporosis. (See "Patient information: Kidney stones in adults" and "Patient information: Osteoporosis prevention and treatment".)

WHERE IS SODIUM FOUND?

The main source of sodium in the diet is the salt added to packaged and processed foods, and in foods from restaurants. Processed foods include prepared frozen meals, canned foods, pickled foods, snack foods, lunch meats, condiments, sauces, and dressings, just to name a few. Sodium found in processed food accounts for about 80 percent of a person's daily sodium intake in a typical Western diet, and can quickly add up, even without the use of the salt shaker.

In addition, many people add more salt to foods; just one teaspoon of table salt contains about 2300 milligrams of sodium, which is more than many people need for the entire day. Most fresh foods (fresh unprocessed meats, fish, vegetables and fruit) have a low sodium content, and can be substituted for foods that are high in sodium.

Terms like "low sodium" and "reduced sodium" can be confusing. Table 1 provides a guide to what these terms mean (table 1).

Guidelines — Several professional organizations have issued evidence-based guidelines for reducing sodium intake. Most clinicians agree that people with high blood pressure should consume less than 2000 milligrams (2 grams) of sodium per day. People with other conditions may be advised to consume even less (1500 to 1800 mg per day).

The sodium content of packaged, processed, and prepared foods can usually be determined by reading food labels (figure 1) or consulting a reference book. Many websites provide nutrient data (eg, www.nutrition.gov), and low sodium cookbooks are also available.

It is important to remember that the amount of sodium listed is for a particular serving size; eating more or less than the listed serving size changes the amount of sodium consumed.

HOW DO I CUT DOWN ON SODIUM?

Although it is difficult to abruptly cut back on the amount of sodium in the diet, most people find that they do not miss the sodium if they cut back gradually. Fresh herbs, spice blends without sodium, citrus and flavored vinegar make tasty alternatives to the salt shaker. Salt is an acquired taste and taste buds can be retrained in less than two to three weeks, if people stick with the lower sodium diet.

It may be helpful to keep a detailed food record and add up sodium intake. Within a short period of time (less than a week), the main sources of sodium can be identified and daily intake can be calculated.

Suggestions to decrease sodium include the following:

• Put away the salt shaker and reduce or eliminate salt in cooking. Experiment with spices, garlic, onions or lemon instead.
• Look for low sodium products such as spice blends, tomato products, and tuna.
• Make a list of healthy low sodium foods to substitute. Many groceries now supply this information for their stores.
• When dining out, request the food be prepared without salt, have dressings or sauces on the side, and avoid bacon bits, cheese, and croutons at the salad bar.
• Do not add salt to food while cooking or before eating. Teach family members to taste food before adding salt.
• Avoid eating at fast food restaurants. If this is not possible, choose restaurants that offer fruits or vegetables without sauces or dressings. Ask that no salt be used to prepare food, when possible.
• Do not use salt substitutes (especially those high in potassium) unless a healthcare provider approves. Herb and spice combinations that are salt-free are widely available and can be used to flavor foods.
• Water softeners remove calcium and add sodium to drinking water. Do not drink softened water. When purchasing bottled water, check the label to ensure that it does not contain sodium.
• Look at labels for over the counter medications. Avoid products that contain sodium carbonate or sodium bicarbonate. Sodium bicarbonate is baking soda.
• Fresh fruits and vegetables are generally low in sodium. In addition, a diet rich in fruits and vegetables provides additional benefits in lowering blood pressure. The DASH diet (Dietary Approaches to Stop Hypertension) is a well known intervention to treat high blood pressure. The DASH diet requires the person to eat four to five servings of fruit, four to five servings of vegetables, and two to three servings of low-fat dairy, and all foods must contain less than 25 percent total fat per serving.

Foods to choose — The following are examples of foods that are generally low in sodium. Check the label to determine the amount of sodium as amounts can vary from one brand to another.

• Breads — Whole grain breads, English muffins, bagels, corn and flour tortillas, most muffins
• Cereals — Many cooked low salt (read the label to determine sodium content) hot cereals (not instant) such as oatmeal, cream of wheat, rice, or farina, puffed wheat, puffed rice, shredded wheat
• Crackers and snack foods — All unsalted crackers and snack foods, unsalted peanut butter, unsalted nuts or seeds, unsalted popcorn
• Pasta, rice, and potatoes — Any type of pasta (cooked in unsalted water), potatoes, white or brown rice
• Dried peas and beans — Any cooked dried beans or peas (without seasoning packet), or low salt canned beans and peas
• Meats and protein — Fresh or frozen beef, poultry, and fish; low sodium canned tuna and salmon; eggs or egg substitutes
• Fruits and vegetables — Any fresh, frozen, or canned fruit, any fresh or frozen vegetables without sauce, canned vegetables without salt, low-salt tomato sauce/paste
• Dairy products — Milk, cream, sour cream, non-dairy creamer, yogurt, low-sodium cottage cheese, low sodium cheese, ricotta and mozzarella cheese
• Fats and oils — Plant oils (olive, canola, corn, peanut), unsalted butter or margarine
• Soups — Salt-free soups and low-sodium bouillon cubes, unsalted broth, homemade soup without added salt
• Desserts — Gelatin, sherbet, pudding, ice cream, salt-free baked goods, sugar, honey, jam, jelly, marmalade, syrup
• Beverages — Coffee, tea, soft drinks, fruit flavored drinks, low salt tomato juice, any fruit juice
• Condiments — Fresh and dried herbs; lemon juice; low-salt mustard (not commercially available but can be made at home), vinegar, Tabasco sauce; low- or no-salt ketchup; seasoning blends that do not contain salt

Foods to avoid — Many foods, especially those that are processed, have a high sodium content. Items that can be substituted for high sodium foods are listed in table 2 (table 2).

• Breads — Biscuits, prepared mixes (pancake, muffin, cornbread), instant hot cereals, many boxed cold cereals, self-rising flour
• Crackers and snack foods — Salted crackers and snack items (chips, pretzels, popcorn), regular peanut butter, prepared dips/spreads, salted nuts or seeds
• Pasta, rice, and potatoes — Macaroni and cheese mix; rice, noodle, or spaghetti mixes; canned spaghetti; frozen lasagna; instant potatoes; seasoned potato mixes
• Beans and peas — Beans or peas prepared with ham, bacon, salt pork, or bacon grease; all canned beans
• Meats and proteins — Salted, smoked, canned, spiced, and cured meat, poultry or fish; bacon; ham; sausage; lunch meats; hot dogs; breaded frozen meat, fish, or poultry; frozen dinners; pizza
• Fruits and vegetables — Regular canned vegetables and vegetable juices, regular tomato sauce and tomato paste, olives, pickles, relishes, sauerkraut, frozen vegetables in butter or sauces, crystallized and glazed fruit, maraschino cherries, fruit dried with sodium sulfite
• Dairy products — Buttermilk, Dutch processed chocolate milk, processed cheese slices and spreads, cottage cheese, aged or natural cheese
• Fats and oils — Prepared salad dressings, bacon, salt pork, fat back, salted butter or margarine
• Soups — Regular canned or prepared soups, stews, broths, or bouillon; packaged and frozen soups
• Desserts — Packaged baked goods
• Beverages — Softened water; carbonated beverages with sodium or salt added; regular tomato juice (V-8); ask about alcoholic beverages
• Condiments — Table salt, lite salt, bouillon cubes, meat extract, taco seasoning, Worcestershire sauce, tartar sauce, ketchup, chili sauce, cooking sherry and wine, onion salt, mustard, garlic salt, soy sauce, tamari, meat flavoring or tenderizer, steak and barbecue sauce, seasoned salt, monosodium glutamate (MSG), Dutch processed cocoa

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed every four months on our web site (www.uptodate.com/patients).

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information

Patient information: Chronic kidney disease
Patient information: Heart failure
Patient information: Kidney stones in adults
Patient information: Osteoporosis prevention and treatment

Professional level information

Diet in the treatment and prevention of hypertension
Salt intake, salt restriction, and essential hypertension

The following organizations also provide reliable health information.

• Medline Plus

      (www.nlm.nih.gov/medlineplus/ency/article/002415.htm, available in Spanish)

• American Heart Association

      (www.americanheart.org/presenter.jhtml?identifier=552)

• National Kidney Foundation

      (www.kidney.org/atoz/atozItem.cfm?id=175)

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