Sodium and Chlorine in human body and its nutrient needs

Sodium and Chlorine in human body and its nutrient needs

1. Sodium and Chlorine

2. Introduction Salt was among the first of the specific nutrients recognized . Table salt is the most common use of salt The cation sodium and the anion chloride are normally found in most foods together as sodium chloride It is widely distributed in nature, where it occurs not only in the sea and other saline waters but also in dry deposits as rock salt The concentration of salt in seawater averages 2.68 percent.

3. It is essential in plants and animals for normal metabolism Value of salt in the diet of animals and humans was recognized hundreds of years ago The strong craving for salt is an innate urge for all animals The transition from a nomadic to an agricultural way of life, with dependence on cereals or vegetables rather than meat and milk, was only sustainable with dietary supplements of salt Infusing sodium in patients suffering from cholera produced a beneficial effect

4. The value of supplementary salt for cattle was first demonstrated experimentally by Boussingault (1847) Babcock (1905) reported his classical studies on the effect of salt deprivation on lactating dairy cows Aines and Smith (1957) identified sodium rather than chlorine as the element primarily concerned During this period, the need for supplemental salt by pigs and poultry fed on cereal-based rations was established

5. Absorption, Metabolism and Excretion Sodium and chloride ions are absorbed by animals principally from the upper small intestine Approximately 80 percent of the sodium and chloride entering the gastrointestinal tract arises from internal secretions such as saliva, gastric fluids, bile, and pancreatic juice Thus, large variations in salt intake have relatively small effects on the total amount of sodium and chloride entering the gastrointestinal tract

6. The majority of ingested sodium chloride is excreted in the urine, provided that sweating is not excessive All three elements (sodium, chloride and potassium) are lost via skin secretions, but there are major differences between species

7. In non-ruminants, including the horse, sodium is the major cation in sweat and salt concentrations in sweat can reach 4.5 % Horses, mules and donkeys sweat profusely when exercised, but the high loss of sodium balances the loss of water and provides a defense against hyponatraemia

8. Plasma levels of sodium are controlled, in part, by aldosterone (adrenal glands, which sit above the kidneys), which functions to increase sodium reabsorption from the kidney tubule Other control is exercised by the antidiuretic hormone of the posterior pituitary, which is responsive to changes in osmotic pressure of the extracellular fluid

9. Adrenal Function .

10. Both hormones act to maintain a constant ratio of sodium to potassium in the extracellular fluid Chloride metabolism is controlled in relation to sodium so that excess kidney excretion of sodium is accompanied by chloride

11. Regulation of sodium status in the face of fluctuations in sodium intake is achieved principally by the control of reabsorption in the proximal tubule of the kidney Sodium reabsorption in the distal tubule can be impaired by excess potassium but enhanced by aldosterone, so that urinary losses become negligible when sodium intakes are low

12. With reduced salt intake, reduced blood volume, or reduced blood pressure, the renin-angiotensin-aldosterone axis is stimulated When the renin-angiotensin-aldosterone system is less responsive, as with advancing age, there is a greater blood pressure reduction from a reduced intake of sodium chloride

13. The major cation of the extracellular fluid is sodium. The typical daily diet contains 130-280 mmol (8-15 g) sodium chloride. The body requirement is for 1-2 mmol per day, so the excess is excreted by the kidneys in the urine Reference range (intervals) for sodium Serum 136-145 mM Cerebrospinal fluid 130-150 mM Sweat 10-40 mM Urine (varies with intake) 40-220 mmol /day

14. Imbalance An increase in dietary sodium from low to modest excess increased the water intake of lactating animals

15. Functions of Sodium and Chloride Sodium and chloride maintain osmotic pressure, regulate acid–base equilibrium and control water metabolism in the body Sodium is the major cation in the ECF and chloride the major anion, at concentrations of 140 and 105 mmol , respectively Sodium plays a key role in providing an osmotic skeleton ’ which was ‘clothed’ with an appropriate volume of water When ion intakes increase, water intakes also increase to protect the gut, facilitate excretion and to ‘clothe’ the enlarged ‘ skeleton’.

16. There are some marked contrasts between sodium and potassium Sodium makes up over 90% of the bases of the serum, but little is present in the blood cells There are significant stores of sodium in the ovine skeleton , which may contain 3–5 g Na kg -1 Chlorine is found both within the cells and in the body fluids, including the gastric secretions, where it occurs as hydrochloric acid ( HCl ) and in the form of salts

17. Chloride also serves as an important component of gastric juice as hydrochloric acid

18. Deficiency symptoms Signs of a combined sodium and chlorine deficiency in cattle, sheep , swine , and horses include a salt craving evidenced by the animals' licking soil , rocks , wood, and other objects Eventually, there is a loss of appetite and productive parameters are adversely affected Cattle and horses take on an unthrifty appearance, and their hair coats roughen

19. In sheep, wool growth is greatly reduced In poultry, accompanying the reduction in productive performance , there appear nervous signs and dehydration The end point of long-term salt deficiency for all animals is death

20. Chloride deficiency occurs only when there is also a loss of sodium caused by excessive sweating, chronic diarrhea or vomiting or some kidney disorders. These losses may result in metabolic alkalosis , a disorder of the body’s pH, or acid-base balance , which may lead to coma or death.

21. In human beings, NaCl deficiency results in   hyponatremia include headache, nausea, vomiting, muscle cramps, fatigue, disorientation, and fainting. Complications of severe and rapidly developing hyponatremia may include cerebral edema (swelling of the brain), coma , and brain damage

22. FACTORS AFFECTING SODIUM AND CHLORIDE REQUIREMENTS Physical Activity and Temperature Physical activity can potentially affect sodium chloride balance , mostly from increased losses in sweat Individuals who exercise strenuously in the heat on a daily basis can lose substantial amounts of sodium The loss of sodium in sweat is dependent upon diet , sodium intake, sweating rate, hydration status , and degree of acclimatization to the heat

23. The amount of sodium lost in sweat is less in those acclimatized to the heat than in those who are not Sodium sweat loss was reported to be significantly greater when subjects performed a running exercise than when the subjects sat in a climatic chamber at 40°C Exposure to heat without exercise, however, also alters sweat sodium concentration

24. Effects of Nutrients on Urinary Losses of Sodium Potassium: Administration of potassium salts has been shown to increase urinary sodium excretion Both potassium bicarbonate and potassium chloride have demonstrated substantial and comparable effects on increasing urinary sodium excretion At a new steady state, sodium intake and excretion become equivalent Potassium may inhibit sodium reabsorption in the distal tubule of the kidney

25. Calcium Higher intakes of sodium result in increased urinary excretion of calcium When placed for one week each on a low calcium (200 mg/day) diet or a high calcium (1,800 mg/day) diet , there was no difference in the urinary excretion of sodium

26. Diuretics Diuretics increase the urinary excretion of water, sodium and chloride As a result, hyponatremia and hypochloremia have been observed with the use of diuretics This appears to be a consequence of impaired water excretion rather than excessive sodium loss since it can be corrected by water restriction

27. Diabetes Diabetes is associated with hyperglycemia when the renal threshold for glucose reabsorption is exceeded The osmotic effect of glucose on the renal tubule is associated with a passive increase in the renal excretion of sodium and water In acute situations , when the hyperglycemia is marked, volume depletion, hypotension, and hyponatremia may occur This is generally corrected by the intravenous administration of sodium chloride and water, as well as insulin, to reduce the elevated blood glucose levels

28. Sources In general, food/feedstuffs do not contain sufficient sodium to provide for optimum productive performance in humans, livestock and poultry Most plant and plant products contain relatively small amounts of sodium in comparison to animal products Oats contained only 0.008 percent sodium, whereas fish contained 2.52 percent With regard to chlorine, the broadest range of values occurred between grains (0.03 percent) and fish ( 4.63 percent)

29. Dietary intake is generally as sodium chloride ( common table salt). Small amounts are available when potassium chloride supplements are used for the treatment of potassium deficiencies associated with diuretic use

30. Sodium and chlorine contents, respectively, were for corn (0.004 and 0.06 percent ) clover hay (0.14 and 0.15 percent ) alfalfa hay (0.07 and 0.19 percent ) Soybean meal (0.02 and 0.04 percent ) timothy hay (0.008 and 0.14 percent)

31. TISSUE LEVELS Respective values of sodium and chloride in swine (parts per million fresh weight) cerebrum, 1,886 and 2,769 cerebellum , 1,817 and 2,769 liver , 1,748 and 2,840 kidney , 2,231 and 3,728 heart , 1,265 and 3,195 and spleen, 1,795 and 2,910 .

32. In poultry, chloride derived from chickens fed 10 percent dietary salt (parts per million fresh weight) Tendon, 3,596 lung , 3,010 liver , 1,924 leg muscle, 983 kidney , 2,098

33. Requirements Sodium for Infants 0–6 months 0.12 g (5 mmol )/day of sodium 7–12 months 0.37 g (16 mmol )/day of sodium Chloride for Infants 0–6 months 0.18 g (5 mmol )/day of chloride 7–12 months 0.57 g (16 mmol )/day of chloride Sodium for Children 1–3 years 1.0 g (42 mmol )/day of sodium 4–8 years 1.2 g (53 mmol )/day of sodium Chloride for Children 1–3 years 1.5 g (42 mmol )/day of chloride 4–8 years 1.9 g (53 mmol )/day of chloride Sodium for Men and Women 9–50 years 1.5 g (65 mmol )/day of sodium Chloride, Men and women 9–50 years 2.3 g (65 mmol )/day of chloride

34. Generally , the dietary requirements for sodium in animals of economic importance approximate 0.2 percent, with the lowest value (0.10 percent) being required by growing beef calves and the highest value (0.35 percent) being required by horses Chlorine requirements are less known, but it is apparent that salt supplementation to satisfy the sodium requirements will also satisfy the chlorine requirements

35. Young birds 0.15% of the diet At 21 days 0.25 % Laying hens 0.17 to 0.19%

36. MAXIMUM TOLERABLE LEVELS Maximum tolerable levels of dietary salt in animals were established as follows a level of 4 percent was set for lactating cows a level of 9.0 percent was set for other cattle and sheep a level of 8 percent was set for swine due to a lack of documentation of toxicosis in swine when given adequate supplies of fresh drinking water a level of 2 percent was set for poultry the level of 3 percent for horses and rabbits

37. Toxicosis Effects of salt administration to livestock and poultry at relatively high levels (in excess of 5 percent via the diet and 2 percent via the drinking water ) Fattening steers could tolerate dietary levels of salt of 9.33 percent with few adverse effects In sheep, dietary concentration of 13.1 percent salt caused increased weight loss during lactation and a decreased number of lambs raised , as well as an increase in the blood and milk chloride concentration

38. In swine, salt poisoning prevailed by offering diets containing 6-8 percent salt with a restriction in the availability of drinking water

39. The signs of salt poisoning include Muscular tremors Weakness Nervousness Incoordination Convulsions Paralysis Coma It decreased rate of weight gain and increased mortality in poultry