Sodium is vital not only for maintaining fluid balance, but also for many other essential functions. Unlike many minerals , sodium absorption in the small intestine is extremely efficient, and in a healthy person all of the excess sodium is excreted by the kidneys. In fact, very little sodium is required in the diet (about 200 milligrams) because the kidneys actively reabsorb sodium. The reabsorption of renal sodium is hormonally controlled and allows a relatively constant concentration of sodium in the blood.
Other Functions of Sodium in the Body
The second important function of sodium is nerve impulse conduction. Nerve impulse transmission, sodium cations, then the results from the conducting to a nerve cell and a load difference between nerve cells and extracellular matrix (or voltage) forms. Similar to how current moves through a wire, a sodium current travels through a nerve cell. Stimulating a muscle contraction involves the action of sodium ions as well as other ion movements.
Sodium is essential for nutrient absorption in the small intestine and also re-absorb nutrients in the kidney. Amino acids , glucose, and water must travel from the small intestine to the blood. For this, they pass through intestinal cells on their way to the blood. Transport of nutrients through intestinal cells is facilitated by the sodium-potassium pump, and the sodium-potassium pump creates a higher sodium concentration outside the cell (requires ATP) by removing sodium out of the cell.
Sweating is a homeostatic mechanism for maintaining body temperature, affecting fluid and electrolyte balance. Sweat is mostly water but also contains some electrolytesmostly sodium and chloride. Under normal environmental conditions (i.e., not hot, humid days), water and sodium loss through sweat is negligible, but highly variable between individuals. It is estimated that sixty minutes of high-intensity physical activity such as a tennis match can produce about one liter of sweat; however, the amount of sweat produced is highly dependent on environmental conditions. A liter of sweat typically contains 1 to 2 grams of sodium, so exercising for a few hours can cause a high amount of sodium loss in some people. Additionally, heavy labor can result in significant sodium loss through sweat. In both cases, lost sodium is easily replaced at the next snack or meal.
Hyponatremia or low blood sodium level in athletes is not the result of excessive sodium loss in sweat, rather too much water is drunk. Excess water dilutes the sodium concentration in the blood. Diseases that cause vomiting, sweating, and diarrhea can also cause hyponatraemia. Symptoms of hyponatraemia (often as the underlying cause), also called water poisoning, include nausea, muscle cramps, confusion, dizziness, and, in severe cases, coma and death. The physiological events that occur in water poisoning are:
Hyponatremia in endurance athletes (such as marathon runners) can be prevented by drinking the right amount of water, which is about 1 glass every twenty minutes during the activity. Sports drinks are better at restoring fluid and blood sugar levels than replacing electrolytes. During an endurance event, you would be better off drinking water and eating an energy bar that contains sugar, protein and electrolytes . The American College of Sports Medicine recommends consuming one high carbohydrate (25-40 grams) per hour of exercise along with plenty of water if you exercise for more than an hour.
Be mindful of the fat content as sometimes energy bars contain high doses. If you’re not exercising for more than an hour at high intensity, you can skip sports drinks, but you can’t skip the water. Sports drinks are another source of extra calories, sugar, and salt for those who do not exercise or do not at low to moderate intensity.
Sodium Needs and Dietary Sources
The IOM has set an AI level for sodium at 1,500 milligrams for healthy adults between the ages of nineteen and fifty (Table 3.2 “ Dietary Reference Intake Amounts for Sodium ”). Table salt is about 40 percent sodium and 60 percent chloride. As a reference point, only teaspoons of salt are required in the diet to meet the AI for sodium. AI takes into account the amount of sodium lost in sweat during a level of physical activity and additionally chloride.
Other nutrients contain for adequate intake, the tolerated Upper Absorption Level ( UL ) for sodium is 2,300 milligrams per day for adults. (1 teaspoon of salt contains the recommended 2,300 milligrams of sodium). UL is considered suitable for healthy individuals but not for those with hypertension. (hypertension).
IOM estimates that over 95 percent of men and 75 percent of women in America consume salt in excess of UL. Many scientific studies show that reducing salt intake prevents hypertension, helps lower blood pressure after hypertension is diagnosed, and reduces the risk of cardiovascular disease . IOM, more than fifty people,
He recommends that African Americans, diabetics, and those with chronic kidney disease consume no more than 1,500 milligrams of sodium per day. The American Heart Association (AHA) states that all Americans, not just those listed, should consume less than 1,500 milligrams of sodium per day to prevent cardiovascular disease.
(ND = not determined)
|Age group||Adequate Intake (mg / day)||Tolerable Upper Intake Level (mg / day)|
|Infants (0-6 months)||120||ND|
|Babies (6-12 months)||370||ND|
|Children (1-3 yaş)||1.000||1.500|
|Children (4-8 yaş)||1.200||1.900|
|Children (9-13 yaş)||1.500||2.200|
|Adolescents (14–18 yaş)||1.500||2.300|
|Adults (19–50 yaş)||1.500||2.300|
|Adults (50–70 yaş)||1.300||2.300|
|Adults (> 70 yaş)||1.200||2.300|
Food Sources for Sodium
Most of the sodium in the typical American diet comes from processed and prepared foods. Manufacturers add salt to foods to improve texture and flavor, as well as as a preservative. The amount of salt in similar food products varies greatly.
Some foods, such as meat, poultry, and dairy products, contain naturally occurring sodium. For example, a cup of low-fat milk contains 107 milligrams of sodium. Naturally occurring sodium accounts for less than 12 percent of dietary intake in a typical diet. For the sodium content of various foods, see.
Sodium Content of Selected Foods:
|Food group||Serving size||Sodium (mg)|
|All breads||1 oz||95–210|
|Rice Chex grain||1 ¼ c||292|
|Grape Whole Grain||1 c||362|
|Frozen pizza, plain, cheese||115 gram||450–1200|
|Frozen vegetables, all types||½ c||2–160|
|Salad dressing, regular oil, all kinds||2 tablespoons||110–505|
|Diluted soup (tomato)||8 oz||700–1260|
|Crisps||1 oz/(28,4 g)||120–180|
|Tortilla chips||1 oz/(28,4 g)||105–160|
|Chicken fast food dinner||1 c||1107|
|Soy sauce||1 tablespoons||1029|
|Canned Corn||1 c||384|
|Baked beans, canned||1 c||856|
|Canned tuna||3 oz||50|
|Fresh tuna||3 oz||50|
|Dry Roasted Peanuts||1 c||986|
|American cheese||1 oz||406|
|Tap water||8 oz||12|
Sodium in Nutrition Facts Panel
Sodium levels in milligrams are a required list on the Nutrition Facts label.
The amount of food in the panel (in milligrams) of sodium per serving of the food in question (Figure 3.10 “Nutrition Label”). Food additives are often high in sodium, for example monosodium glutamate (MSG) contains 12 percent sodium.
Additionally, baking soda, baking soda, disodium phosphate, sodium alginate, and sodium nitrate or nitrite also contain significant amounts of sodium. When you see the Nutrition Facts label of a food, you can check the ingredient list to determine the source of the added sodium. Various claims regarding sodium content in foods must comply with Food and Drug Administration (FDA) regulations
“Light in Sodium” or “Low in Sodium” Sodium decreased at least 50 percent
“No Salt Added” or “No Salt” Salt is not added during preparation and processing *
“Lightly Salty” 50 percent less sodium than added to similar foods
“Contains No Sodium” or “Without Salt” Contains less than 5 mg of sodium per serving
“Very Low Salt” Contains less than 35 mg of sodium per serving
“Less salty” Contains less than 140 mg of sodium per serving
* If the food is not sodium free, it must be declared on its packaging that “This is not a sodium free food”.
Tools for Change
To reduce your sodium intake, become a salt-savvy customer by reading processed foods’ labels and ingredient lists and choosing ones that are low in salt. Better still, stay away from processed foods and control the seasoning of your foods. Eating a diet containing less salty foods reduces salt cravings, so you may need to try a lower sodium diet for a week or two before you are satisfied with less salty foods.
For those with hypertension or those looking for a way to reduce their salt use, using salt substitutes to prepare meals is an option. However, many salt substitutes contain less sodium than table salt. Also, keep in mind that most salt in the diet comes from processed foods, not table salt. Salt substitutes often replace sodium with potassium.
People with kidney disease often have trouble getting rid of excess potassium in the diet and are advised to avoid salt substitutes containing potassium. People with liver disorders should also avoid salt substitutes that contain potassium because their treatment is often accompanied by a potassium disorder.
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