Sodium
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Overview
To access basic detailed info on Sodium as an element Wiki gives a good overview at Click Here
In Health Terms - The Norms.
Your body needs sodium to function properly. Low levels of sodium can cause muscle cramping, confusion and seizures. High levels of sodium can cause excessive thirst. Extremely high levels can lead to confusion and seizures.
For adults, a sodium level of 135 to 145 mEq/L is desirable. Lower levels of sodium may indicate that you're retaining too much fluid.
Health effects of sodium
Sodium is a compound of many foodstuffs, for instance of common salt. It is necessary for humans to maintain the balance of the physical fluids system. Sodium is also required for nerve and muscle functioning. Too much sodium can damage our kidneys and increases the chances of high blood pressure. The amount of sodium a person consumes each day varies from individual to individual and from culture to culture; some people get as little as 2 g/day, some as much as 20 grams. Sodium is essential, but controversely surrounds the amount required.
Contact of sodium with water, including perspiration causes the formation of sodium hydroxide fumes, which are highly irritating to skin, eyes, nose and throat. This may cause sneezing and coughing. Very severe exposures may result in difficult breathing, coughing and chemical bronchitis. Contact to the skin may cause itching, tingling, thermal and caustic burns and permanent damage. Contact with eyes may result in permanent damage and loss of sight.
The Sodium Cycle
Most of the body's sodium is located in the blood and in the fluid in the space surrounding the cells. Sodium is required by all cells in the body to maintain a normal fluid balance (see Water Balance: Introduction). Sodium plays a key role in normal nerve and muscle function. Sodium is taken in through food and drink and lost primarily in sweat and urine. Healthy kidneys maintain a consistent level of sodium in the body by adjusting the amount excreted in the urine.
When sodium intake and loss are not in balance, the total amount of sodium in the body is affected. Changes in the total amount of sodium are closely linked to changes in the volume of water in the blood. A loss of sodium from the body does not necessarily cause the level of sodium in the blood to decrease but does cause blood volume to decrease. When blood volume decreases, blood pressure also decreases, heart rate increases, and light-headedness and sometimes shock occur.
Conversely, the blood volume increases when there is too much sodium in the body. When excess sodium accumulates in the body, extra fluid accumulates in the space surrounding the cells. As a result, the tissues, especially in the feet and ankles, swell (a condition called edema).
The body continually monitors blood volume. Sensors in the heart, blood vessels, and kidneys detect when blood volume becomes too high and stimulate the kidneys to increase sodium excretion, thus returning blood volume to normal. Sensors in the blood vessels and kidneys detect when blood volume is becoming low and trigger one of several mechanisms that result in an increase in blood volume. One such mechanism involves the adrenal glands, which secrete the hormone aldosterone. Aldosterone causes the kidneys to retain sodium and to excrete potassium (see Adrenal Gland Disorders). Another mechanism involves the pituitary gland, which secretes antidiuretic hormone. Antidiuretic hormone causes the kidneys to conserve water. The retained sodium and water lead to decreased urine production, which eventually leads to an increase in blood volume.
Blood volume most closely parallels the total amount of sodium in the body, which cannot be directly measured with a laboratory test and requires assessment by a doctor. The sodium level in the blood, on the other hand, can be easily measured. Changes in the sodium level in the blood do not necessarily parallel changes in the total amount of sodium in the body or changes in blood volume and have a different set of causes.
Details
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. Hyponatremia 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 - 2 225
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
TOO LITTLE Sodium - HYPONATREMIA
In Hyponatremia, the level of sodium in the blood is too low. Hyponatremia occurs when sodium has been overdiluted in the body. Sodium can be overdiluted when people drink enormous amounts of water—as people with certain psychiatric disorders occasionally do—or when people who are hospitalized receive large amounts of water intravenously. In either case, the amount of fluid taken in exceeds the kidneys' capacity to eliminate the excess. Intake of smaller amounts of water—sometimes as little as 1 quart a day—can lead to hyponatremia in people whose kidneys are not functioning normally, such as people with kidney failure. Hyponatremia also often occurs in people with heart failure or cirrhosis. Excessive chronic loss of fluids, as occurs with chronic diarrhea, can also result in hyponatremia.
Another cause of hyponatremia is the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). People who have SIADH have a low sodium level because the pituitary gland secretes too much antidiuretic hormone. Hyponatremia also occurs in people who have underactive adrenal glands (Adrenal Gland Disorders: Addison's Disease) and who thus excrete too much sodium in the urine.
When the sodium level in the blood falls quickly, symptoms tend to develop rapidly and be more severe. The brain is particularly sensitive to changes in the sodium level in the blood. Therefore, symptoms such as lethargy and confusion occur first. As hyponatremia becomes more severe, muscle twitching and seizures may occur; stupor, coma, and death may follow. The diagnosis of hyponatremia is made by measuring the sodium level in the blood. Determining the cause of hyponatremia is more difficult and requires a full assessment by a doctor.
Mild hyponatremia can be treated by restricting fluid intake to less than 1 quart per day. Severe hyponatremia is an emergency. To treat it, doctors slowly increase the level of sodium in the blood with drugs, intravenous fluids, or sometimes both. Increasing the level too rapidly can result in severe and often permanent brain damage.
TOO MUCH Sodium - HYPERNATREMIA
In Hypernatremia, the level of sodium in the blood is too high. The body contains too little water relative to the amount of sodium. The sodium level in the blood becomes abnormally high when water loss exceeds sodium loss, as occurs with dehydration. In most people, hypernatremia results from dehydration (see Water Balance: Dehydration).
Hypernatremia occurs in people who drink too little water and in those who have diarrhea, vomiting, fever, excessive sweating (particularly during hot weather), or abnormal kidney function.
For example: hypernatremia may occur in diabetes insipidus, in which the kidneys excrete too much water (see Pituitary Gland Disorders: Central Diabetes Insipidus). Other causes of hypernatremia include head trauma or neurosurgery involving the pituitary gland, disorders of other electrolytes (a high calcium level or low potassium level), sickle cell disease, and use of drugs (such as lithiumSome Trade Names LITHANE LITHONATE , demeclocyclineSome Trade Names DECLOMYCIN , or diuretics).
Hypernatremia is most common among older people, who tend to sense thirst more gradually and less intensely than younger people do. Older people who are bedridden or demented may be unable to obtain water even if they feel thirsty. In addition, the kidneys' ability to concentrate urine declines in advanced age, so older people are less able to conserve water. Older people who take diuretics, which force the kidneys to excrete more water, are at particular risk of hypernatremia—especially when the weather is hot or they become ill and do not drink enough water.
The most important symptoms of hypernatremia result from brain dysfunction. Severe hypernatremia can lead to confusion, muscle twitching, seizures, coma, and death. The diagnosis is made by determining that the sodium level in the blood is high.
Hypernatremia is treated by replacing water. In all but the mildest cases, dilute fluids (containing water and a small amount of sodium in carefully adjusted concentrations) are given intravenously. The sodium level in the blood is reduced very slowly, because correcting the condition too rapidly can cause permanent brain damage.
How can I reduce the sodium in my diet?
Choose fresh, frozen or canned food items without added salts. Select unsalted nuts or seeds, dried beans, peas and lentils. Limit the amount of salty snacks you eat, like chips and pretzels. Avoid adding salt and canned vegetables to homemade dishes. Select unsalted, fat-free broths, bouillons or soups. Select fat-free or low-fat milk, low-sodium, low-fat cheeses, as well as low-fat yogurt. Specify what you want and how you want it prepared when dining out. Ask for your dish to be prepared without salt.
Use spices and herbs to enhance the taste of your food.
Articles
References
American Heart Association: Click Here
Lenntech: Click Here
Merck On Line: Click Here
Northwestern University: Click Here
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