Sodium

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Sodium is a nutrient (macro-mineral). It is a metallic element which is an important constituent of the human body. Sodium plays a major role in water balance.

Sodium is one of the major components of table salt. An investigation, called the Intersalt Study, of 10 000 people from 32 countries, found that there was a very strong correlation between a high sodium consumption and high blood pressure, especially in sodium-sensitive people. The results can be interpreted in a number of ways, but most dietitians agree that high sodium intakes can be harmful. Sodium can also increase the risk of oedema (swelling, particularly in joints, caused by an accumulation of fluids). The current average sodium intake of adults in the UK is 3.2 g per day. The government recommends that this should be decreased to 1.6 g. One simple way of reducing sodium intake is not to add table salt to food.

Sodium deficiency is rare, but it can occur if losses from heavy sweating are not replaced. A deficiency leads to nausea and muscular cramps.

Sodium requirements are almost invariably satisfied by the normal diet. The body contains about 100?g of sodium and the average diet contains 3-6g, equivalent to 7.5-15g of sodium chloride (salt); the requirement is less than 0.5g sodium/day. The intake varies widely between individuals and excretion varies accordingly. Excessive intake of sodium is associated with hypertension.

Description

Sodium, a nutrient (macro-mineral), is known to most people in the form of table salt. Sodium is one of the minerals that the body needs in relatively large quantities. Humankind's taste for sodium reaches far back into the distant past. Much like today, sodium was popular in antiquity as a food preservative and an ingredient in snacks. In some ancient societies, sodium was even used as a form of currency.

In modern times, most Americans and other Westerners consume far too much of the mineral, and it is easy to see why. One obvious culprit is table salt, which has a high sodium content. The mineral is also found in many of America's favorite foods (or the chemicals used to preserve those foods). Sodium can be found in potato chips and a variety of other snacks, processed foods, meat, fish, butter and margarine, soft drinks, dairy products, canned vegetables, and bread, just to name a few sources. A single slice of pizza can supply the body with all the sodium it needs for one day (about 500 mg), while a teaspoon of table salt contains four times that amount.

A certain intake of sodium is considered essential to life. The mineral is a vital component of all bodily fluids, including blood and sweat. Often working in combination with other minerals such as potassium, sodium helps to manage the distribution and pH balance of these fluids inside the body and plays an important role in blood pressure regulation. Sodium is referred to as an electrolyte because it possesses a mild electrical charge when dissolved in bodily fluids. Due to this charge, sufficient amounts of the mineral are necessary for the normal functioning of nerve transmissions and muscle contractions. Sodium also helps the body to retain water and prevent dehydration, and may have some activity as an antibacterial.

The important benefits associated with sodium become apparent in cases of sodium deficiency, which is relatively uncommon. Sodium deficiency is most likely to occur in cases of starvation, diarrhea, intense sweating, or other conditions that cause rapid loss of water from the body. People who suffer from low sodium levels may experience a wide range of bothersome or serious health problems, including digestive disorders, muscle twitching or weakness, memory loss, fatigue, and lack of concentration or appetite. Arthritis may also develop. These problems usually occur when fluids that belong in the bloodstream take a wrong turn and enter cells.

General Use

Most Americans consume anywhere from 3,000 mg to 20,000 mg of sodium a day. These amounts are much more than the body needs to function at an optimal level. Many nutrition experts are concerned about the rise in sodium intake in the general population in the last twenty years. Much of this increase is due to the popularity of fast foods and salty snacks, including the sale of high-sodium snack foods in school cafeterias or vending machines.

While sodium deficiencies are rare, supplements may be required in people with certain medical conditions such as Addison's disease, adrenal gland tumors, kidney disease, or low blood pressure. More sodium may also be needed by those who experience severe dehydration or by people who take diuretic drugs.

Though taking extra amounts of sodium is not known to improve health or cure disease, the mineral may have some therapeutic value when used externally. A number of medical studies in people suggest that soaking in water from the Dead Sea may be beneficial in the treatment of various diseases such as rheumatoid arthritis, psoriatic arthritis, and osteoarthritis of the knees. Located in Israel, the Dead Sea is many times saltier than ocean water and rich in other minerals such as magnesium, potassium, and calcium. In one small study, published in 1995 by researchers from the Soroka Medical Center in Israel, nine people with rheumatoid arthritis showed significant improvement in their condition after bathing in the Dead Sea for 12 days. The control group in the study, whose members did not bathe in the Dead Sea, failed to improve. The beneficial effects of the Dead Sea soaks lasted for up to three months after they had stopped bathing in the famous body of water. Despite intriguing findings such as these, no one knows for certain if sodium plays a major role in the therapeutic powers associated with the Dead Sea soaks.

Sodium has a reputation as a germ killer. Some people use a sodium solution as an antibacterial mouthwash to combat microorganisms that cause sore throat or inflamed gums. Plain saltwater soaks have also been recommended as a remedy for sweaty feet. Salt is believed to have a drying effect by soaking up excess perspiration. In ages past, saltwater soaks were used to relieve sore or aching muscles.

Preparations

In the late 1990s the National Academy of Sciences established the recommended daily allowance (RDA) of sodium as between 1,100 and 3,300 milligrams.

To prepare a sodium mouthwash, mix 1 tsp of table salt with a glass of warm water. The solution should be swished around in the mouth for about a minute or so. Then spit the mixture out. Try not to swallow the solution, as it contains about 2,000 mg of sodium.

Sodium is available in tablet form, but supplements should only be taken under the supervision of a doctor. As mentioned earlier, most people already get far too much sodium in their diets.

A trip to the Dead Sea is not necessary in order to enjoy its potential benefits. Dead Sea bath salts are also available.

Precautions

People who wish to take sodium supplements or increase their sodium intake should talk to a doctor first if they have high blood pressure (or a family history of the disease), congestive heart failure (or other forms of heart or blood vessel disease), hepatic cirrhosis, edema, epilepsy, kidney disease, or bleeding problems.

Studies investigating the role of sodium in the development of high blood pressure have produced mixed results. However, sodium is widely believed to contribute to the development of the disease in susceptible people. For this reason, most doctors and major health organizations around the world recommend a diet low in sodium. Eating a low-sodium diet may actually help to lower blood pressure, especially when that diet includes sufficient amounts of potassium.

A 20-year-long follow-up study to the National Health and Nutrition Examination Survey that was conducted between 1971–1975 reported in 2002 that high levels of sodium in the diet are an independent risk factor for congestive heart failure (CHF) in overweight adults. The authors of the study suggested that lowering the rate of sodium intake may play an important role in lowering the risk of CHF in overweight populations as well as individuals.

Another good reason for limiting one's intake of sodium is the link between high levels of dietary sodium and an increased risk of stomach cancer. This risk is increased if a person's diet is also low in fresh fruits and vegetables.

Apart from an increase in blood pressure, high levels of sodium may cause confusion, anxiety, edema, nausea, vomiting, restlessness, weakness, and loss of potassium and calcium.

People who are concerned about consuming too much sodium should try to keep their sodium intake below 2500 mg per day. This is the level recommended by the US Department of Health and Human Services and the US Department of Agriculture in their 2000 Dietary Guidelines for Americans. Ways to reduce sodium intake include the following:

* Reading the Nutrition Facts labels on processed food items. The amount of sodium in a specific processed food, such as cake mix or canned soup, can vary widely from brand to brand.

* Retraining the taste buds. A taste for salt is acquired. A gradual decrease in the use of salt to season foods gives the taste buds time to adjust.

* Using other spices and herbs to season food.

* Cooking from scratch rather than using processed foods.

* Substituting fresh fruits and vegetables for salty snack foods.

* Tasting food at the table before adding salt. Many people salt their food automatically before eating it, which often adds unnecessary sodium to the daily intake.

* Choosing foods that are labeled "low sodium" or "sodium free."

* Watching the sodium content of over-the-counter medications, and asking a pharmacist for information about the sodium content of prescription drugs.

Restricting sodium intake is not usually recommended for women who are pregnant or breast-feeding.

Side Effects

Dietary sodium is not associated with any bothersome or significant short-term side effects. In some people, however, salt tablets may cause upset stomach or affect kidney function.

Interactions

Sodium may promote the loss of calcium and potassium from the body. In addition, sodium in the diet should be restricted for such medications as antihypertensives (drugs to control blood pressure) and anticoagulants (blood thinners) to be fully effective.

Resources

Books

Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part I: Food for Thought. New York: Simon & Schuster, 2002.

Sifton, David W. PDR Family Guide to Natural Medicines and Healing Therapies. New York: Three Rivers Press, 1999.

Periodicals

Becker, Elizabeth, and Marian Burros. "Eat Your Vegetables? Only at a Few Schools." New York Times, January 13, 2003.

He, J., L. G. Ogden, L. A. Bazzano, et al. "Dietary Sodium Intake and Incidence of Congestive Heart Failure in Overweight US Men and Women: First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study." Archives of Internal Medicine 162 (July 22, 2002): 1619-1624.

Ngoan, L. T., T. Mizoue, Y. Fujino, et al. "Dietary Factors and Stomach Cancer Mortality." British Journal of Cancer 87 (July 1, 2002): 37-42.

Nielsen, S. J., A. M. Siega-Riz, and B. M. Popkin. "Trends in Food Locations and Sources Among Adolescents and Young Adults." Preventive Medicine 35 (August 2002): 107-113.

Sukenik, S. "Balneotherapy for Rheumatic Diseases at the Dead Sea Area." Israeli Journal of Medicine and Science. (1996): S16–9.

Sukenik, S., D. Flusser, and S. Codish et al. "Balneotherapy at the Dead Sea Area for Knee Osteoarthritis." Israeli Journal of Medicine and Science. (1999):83–5.

Organizations

American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. http://www.americanheart.org/.

National Academy of Sciences. 500 Fifth Street, NW, Washington, DC 20001. .

[Article by: Greg Annussek; Rebecca J. Frey, PhD]

Sodium: Part II

Sodium, a macromineral, is actually necessary to regulate your blood pressure and blood volume. Without sodium, you wouldn't have any blood pressure at all. Sodium occurs naturally in many foods, including vegetables and dairy products. In addition, sodium is in drinking water and in many processed foods and condiments, such as soy sauce, processed meats, and canned soups and vegetables.

The problem with sodium is that Americans are consuming way too much of it-between 4,000 and 6,000 extra milligrams per day. Table salt is 40% sodium, and one teaspoon of salt contains 2,300 milligrams of sodium. Sodium can be a major dietary culprit when it comes to high blood pressure, so it’s important to monitor your sodium intake.

How Much Sodium Is Enough?

The American Heart Association recommends that for every 1,000 calories of food you eat, the sodium intake should be 1,000 milligrams or less and should not exceed the 3,300 milligram daily limit for adults.

However, your sodium intake may be dependent upon your medical condition and the prescriptions you take. People who have hypertension may be advised by their doctors to consume a low-sodium diet.

The sodium content of most foods is listed on the food label. In general, fast foods, processed meats and canned vegetables and soups contain lots of added sodium.

Limiting Sodium

Processed food often contains a lot of sodium. Watch out for dried sauce mixes, boxed dinners, and snack foods like potato chips and pretzels. Try these tips to reduce the sodium in your diet:

* Remove the salt shaker from the table.

* Choose fresh, frozen or canned food items without added salts.

* Select unsalted nuts or seeds, dried beans, peas and lentils.

* Avoid adding salt and canned vegetables to homemade dishes.

* Select unsalted, fat-free broths, bouillons or soups.

* When dining out, be specific about what you want and how you want it prepared. Request your dish to be prepared without salt.

* Learn to use spices and herbs to enhance the taste of your food instead of salt.

Physiological Functions

Sodium is the primary electrolyte that regulates the extracellular fluid levels in the body. Sodium is essential for hydration because this mineral pumps water into the cell. In turn, potassium pumps the by-products of cellular processes out of the cell, eventually eliminating these "wastes" from the body.

In addition to maintaining water balance, sodium is necessary for osmotic equilibrium, acid-base balance and regulation of plasma volume, nerve impulses and muscle contractions.

Factors Affecting Availability

Considering that the sodium level of the typical American diet ranges from 3,000-5,000 mg daily, most people actually consume far more sodium than that required for health. However, endurance athletes (exercising > 2 hours in duration) have increase sodium levels due to excessive sweat losses). On the other hand, hypertensive individuals are
recommended to limit their sodium intake < 2,400 mg daily (along with eating a low-fat diet rich in fruits, vegetables, whole grains and low-fat dairy foods) for blood pressure management.

Deficiency

Since the minimum physiological requirement for sodium is only 500 mg daily, Americans well exceed their sodium intake. However, athletes who eat mostly fresh foods and consume water (versus sports drink) during exercise maybe at risk for hypoatremia characterized by lethargy, confusion, muscle twitching, seizures and coma. Hypoatremia may also be due to excessive intake of fluid especially those experiencing renal insufficiency.

Toxicity

Excessive consumption of sodium on a regular basis is often associated with hypertension and edema. High intakes of sodium can also lead to osteoporosis because sodium can increase urinary calcium losses.

No upper safety limits for sodium have been established because the body generally excretes excess sodium through the kidneys. But health organizations recommend daily consumption of sodium < 2,400 mg per day (about half of that found in the typical American diet).

Requirements

The Food and Nutrition Board recommended a sodium intake of < 2,400 mg/day for adults. Although the exact minimum requirements of sodium are not known the table below provides a list of the estimated minimum requirements for sodium:

 

Age	Recommended Sodium Requirements (mg)
Months
0 - 5	120
6 - 11	200
Years
1	225
2 - 5	300
6 - 9	400
10 - 18	500
>18		500

Dietary Sources

Common dietary sources of sodium are often processed food to which salt is added during preparation, such as cheeses, soups, pickles and pretzels. Additionally, processed, commercially prepared or restaurant foods are generally high in sodium.

Sodium Content of Food

 

Food	               Sodium (mg)
Table Salt , 1 tsp	         2358
Pickles, dill, 1 large	1731
Canned chicken soup, 1 cup	850
Sauerkraut, 1/2 cup	780
Pretzels, 1 oz	         486
Cottage cheese, 1/2 cup	459
Sardines, 3 oz	         429
Deli ham, 1 oz	         341
Deli turkey breast, 1 oz	335
Soy Sauce, 1 tsp	         304
Cheese, American, 1 oz	304
Cornflakes, 1 cup	         298
Olives, black, 5 large	192
Deli bologna	         295
Potato Chips, 1 oz	         183

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