Concepts about Minerals | CHAPTER 8 | Basic Science

Concepts about Minerals – Introduction to fundamental concepts of Biological Science including the organization and common characteristics of living matters, cell structures and functions, food production by photosynthesis, harvesting energy, mechanism of cells reproduction, genetics, evolutions, and Human Biology. Introduction to general chemistry including basic concepts about matter, atomic structure, chemical bonds, gases, liquid, and solids, solutions, chemical reactions, acid, bases, and salt;

organic and biochemistry including hydrocarbons and their derivatives, carbohydrates, lipids, proteins, enzymes, vitamins, and minerals, nucleic acids; principles of physics and applications to nursing including gravity and mechanics, pressure, heat and electricity; nuclear chemistry and nuclear physics, effects of radiation on human beings, and protection and disposal. The aim of the course is to acquire knowledge and skills in general biological science, general chemistry and physics.

Concepts about Minerals

In the context of nutrition, a mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. Minerals originate in the earth and cannot be made by living organisms. Plants get minerals from soil. Most of the minerals in a human diet come from eating plants and animals or from drinking water. As a group, minerals are one of the four groups of essential nutrients, the others of which are vitamins, essential fatty acids, and essential amino acids.

The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. All of the remaining elements in a human body are called “trace elements”. The trace elements that have a specific biochemical function in the human body are iron, cobalt, copper, zinc, manganese, molybdenum, iodine, and selenium.

Most chemical elements that are ingested by organisms are in the form of simple compounds. Plants absorb dissolved elements in soils, which are subsequently ingested by the herbivores that eat them, and the elements move up the food chain. Larger organisms may also consume soil (geophagia) or use mineral resources, such as salt licks, to obtain limited minerals unavailable through other dietary sources.

Definition of Mineral:

More than 50 chemical elements are found in the human body, which are required for growth, repair and regulation of vital body functions are called minerals.

or

Minerals are naturally-occurring inorganic substances with a definite and predictable chemical composition and physical properties.

Distribution of minerals in the body:

For good health mineral is very essential. Mineral forms four percent (4%) of body weight.

Classification of Mineral:

The body needs minerals in small amounts to help chemical processes, and to build tissues and fluids. These can be divided into three major groups:

Major minerals:
These are present in the body in large amounts and the daily requirement of man to maintain the optimum nutrition is appreciable. Calcium, sodium, phosphorus, potassium, magnesium etc., are included within this group.

Trace elements:
These are elements required by the body in quantities of less than a few milligrams per day, e.g., iron, iodine, fluorine, zinc, copper, cobalt, chromium, manganese, molybdenum, selenium, nickel, tin, silicon, and vanadium.

Trace contaminants with no known function:
These include lead, mercury, barium, boron and aluminium.

Macro and micro minerals:

Importance of Minerals/Functions of Minerals:

1. Formation of bones and teeth.
2. Maintenance of osmotic pressure of body fluids
3. Maintenance of acids base balance
4. Maintenance of tone of muscles and nerves
5. Some minerals are needed for specific functions like –

• Iron for the formation of Hemoglobin (Hb)
• Sodium for the formation of thyroxin
• Cobalt as the constituent of vitamin B12
• Zinc as the constituent of an enzyme

CALCIUM

Calcium:
Calcium is a major mineral element of the body. It constitutes 1.5-2% of the body weight of an adult man. An average adult body contains about 1200 g of calcium of which over 98 per cent is found in the bones. The amount of calcium in the blood is usually about 10 mg/dl.

Sources of calcium:
1. Animal sources: The best natural sources are milk and milk products e.g., cheese, curd, skimmed milk and better milk.
2. Vegetable sources: The cheapest dietary sources of calcium are green leafy vegetables, A cereals, beans, potatoes, pulses, nut and millets.

Functions of calcium:
The important physiological functions of calcium are –
1. It regulates the permeability of capillary walls.
2. It regulates the excitability of nerve fibres and nerve centres.
3. It also plays a crucial role in the transformation of light to electrical impulses in the retina.
4. It is essential for –

• Formation of bone and teeth
• Contraction of muscles and heart
• Coagulation of blood
• Helps in metabolic action of enzymes and hormones.

Effects of calcium deficiency:

1. Decreased rate of growth.
2. Osteoporosis.
3. Tetany.
4. Confusion
5. Pain
6. Involuntary muscle spasm.
7. Bronchial spasm.
8. Loss of hair.
9. Rough skin.
10. Pitting of teeth.
11. Epileptic fits.

Daily requirement of calcium:

(Ref: K. Park/23rd)

Absorption of calcium:

The absorption of calcium from the intestines into the bloodstream is affected by various physiological and dietary factors. Secretion of hydrochloride acid in the stomach produces an acidic environment that helps keep calcium soluble, thereby promoting absorption A variety of other factors also influence calcium absorption. Vitamin D encourages the absorption of calcium, and lactose (milk sugar) in the diet may do so as well.

Protein in the diet appears to enhance calcium absorption when protein consumption falls between inadequate and adequate levels, yet it does not seem to promote absorption when protein consumption is above the RDA. Phytate phosphorus, the natural form of phosphorus found in legumes and other foods, seems to decrease calcium absorption.

As mentioned previously, both phytates (found in whole grains, legumes, and seeds) and oxalates (found mainly in leafy greens) decrease calcium absorption. Specific types of fiber may also decrease calcium absorption. Aluminum and magnesium containing antacids may decrease absorption and increase calcium excretion.

(Ref: Sheilla John’s/1st/92)

Factors hinder of calcium absorption:

1. Too much phosphorus in the form of phosphate in food,
2. Anything which causes food to pass quickly through the intestine, e.g. infection causing
3. Diarrhea, too much roughage in food.
4. Any substance which forms an insoluble salt with calcium, e.g. excess fatty acid.
5. Deficiency of vitamin D may hinder absorption of calcium.
6. Purgatives, oxalates, excess phosphorus or fatty acids, ptyalin, and deficiencies of vitamin D hinder the absorption of calcium and this affect the use of calcium.

(Ref: T. K. Indrani/1/49)

Calcium excreted from the body:
1. Calcium is excreted mainly with the stools and also through urine
2. Insignificant amount is excreted with the sweat’
3. The average daily loss of calcium is about 700 mg in an adult.
4. The calcium also passes through the glomerular filter and reabsorbed in the renal tubules

Way of maintain calcium balance in the body:

1. Normally in a well-nourished adult person the amount of calcium loss from the body (in stools and urine) is equal to the amount absorbed from the food.

2. Thus, the calcium balance is maintained.

3. There is an automatic adaptation and regulatory phenomenon.

4. When the dietary intake is low, considerably higher percentage of intestinal absorption occurs.
(his is obviously controlled by the parathyroid glands and vitamin D and consequent intestinal mucosal active participation).

5. As and when required, calcium is drawn from the store in the bone.

6. There is significant adaptation through increased intestinal absorption, withdrawal from the store inside bones and diminished urinary excretion to offset the ‘negative calcium balance’ in situations like deficiency of parathyroid hormone or vitamin D, dietary deficiency or intestinal mal-absorption.

7. On the other hand, growing children (and on parenteral administration of vitamin D)
there is ‘positive calcium balance’ due to increased absorption from the dietary content-and simultaneous formation of bone by the mineralization of the matrix by the osteoblastic cells.

(Ref: Essential of Human Nutrition/1/26)

Clinical disorder associated with the metabolic disturbances of calcium:

Even though calcium concentration in blood is usually regulated accurately, the disturbance in the blood calcium is not quite rare.

1. Hypocalcaemia: The classical manifestations of hypocalcaemia are –

• Neuro-muscular irritability.
• Lethargy.
• Paresthesia or abnormal sensation in the limbs.
• Abdominal Pain.

2. Hypercalcaemia: The characteristic clinical features of Hypercalcaemia include-

• Anorexia.
• Nausea
• Vomiting.
• Constipation.
• Muscular hypotonia
• Lethargy.
• Polyuria.
• Mental confusion

PHOSPHORUS

Adult human contains 400 to 700 gm of phosphorus. It is mostly present in body fluids, cells and in enzymes. Phosphorus is essential for the formation of bones and teeth and phospholipids. Phosphorus is commonly found in the food. The phosphorus is absorbed as inorganic salt. Phosphorus is absorbed in the small intestine as inorganic phosphates

(Ref: Onila Salin’s Essential nutrition/1″/42)

Sources of phosphorus:

1. Eggs
2. Meat
3. Fish
4. Cereal
5. Milk
6. Milk products

(Ref: T. K. Indrani/1/50)

Functions of phosphorus:
1. For the calcification of bones and metabolism of carbohydrates, proteins and fats phosphorus is required.
2. It acts as a buffer system in the body.
3. Storage and release of energy is controlled by phosphorus compound
4. Phosphorus is required for the absorption of calcium.
5. Absorption of phosphorus is prevented by excess consumption of iron, magnesium and aluminum in the diet.
6. It is an essential constituent of nucleic acid and nucleoproteins.

(Ref: Onila Salin’s Essential nutrition/1/42)

Deficiency of phosphorus:
Phosphorus deficiency is characterized by

• Weakness.
• Lack of appetite.
• Fatigue.
• Muscle pain.

Daily requirement of phosphorus:

• In case of adult: 400 – 600 mg
• During pregnancy and lactation: 1000 – 1200 mg

SODIUM

Sodium:
Sodium is a mineral, which is very important for the body. Body fluid contains sodium. Human body contain approximately 1.8 g of sodium per kilogram of body weight. The kidneys can conserve sodium. The adult human body contains about 100 gm of sodium ion. Half the quantity is found in extracellular fluid and other half is found in tissue-cells and bones. Through perspiration and urine sodium is lost from the body. On average, 5 to 10 gm sodium chloride is ingested per day in an average die.

Sources of sodium:

a) High sodium is found in –

• Bread.
• Com.
• Rice.
• Wheat flakes.
• Salted crackers.
• Salted butter.
• Salted nuts.. Salted popcorn.
• Dried cooked legumes.
• Salted dried.
• Canned fish.
• Meat
• Bacon.
• Corned beef.
• Dried beef.
• Salted pork
• Sausages.

b) Low sodium:

• Low sodium is found:
• Unsalted bread.
• Butter.
• Margarine
• Meat
• Fresh vegetable
• Fruits.
• Unsalted nuts.
• Fresh whole skim milk.

Functions of sodium:

1. Maintains osmotic pressure in blood and other tissue fluids.
2. Essential for the maintenance of pH ions concentration.
3. In presence of sodium absorption of monosaccharide’s and amino acids from the small intestine take place
4. Sodium is important for initiating and maintaining heartbeat.
5. It helps in contraction of the muscles.

Effects of deficiency of sodium:

1. Hyponatremia.
2. Hypernatremia (If sodium level increase in the plasma)
3. Muscular cramps.
4. Marked general weakness.
5. Mental lassitude.
6. Dyspnoea on exertion

(Ref: Onila Salin’s Essential nutrition/1/48)

Daily requirement of sodium:

Adult requirement of sodium is 10 to 15 g/day.

Excretion of sodium:

• On an average diet about 3 to 5 gm of sodium (corresponding to 8 to 12 gm NaCl) is excreted in urine.
• On a low salt diet and in starvation, urinary excretion may fall to very low levels.

Effects of high intakes of sodium:

Short-term over consumption of sodium (as from eating one very-high-sodium meal) may produce edema (fluid retention). The excess sodium is excreted quickly by the kidneys as long as adequate water is consumed. On the other hand, long-term high intakes of sodium, especially in the form of table salt, have been related to hypertension (high blood pressure) in salt-sensitive people.

SODIUM CHLORIDE

Sodium chloride (NaCI):
All minerals except sodium chloride (NaCl) are usually present in sufficient amounts in a well- balanced diet. Sodium chloride is the only mineral which is taken in more or less pure form in addition to the amount present in natural foods. The loss of sodium chloride may be about 2-5 gm per hour of very hard-work or 10-20 gm per day. Heat cramps may be prevented by taking 10–20 gm per day by adding Nacl (0.3-0.5%) to drinking water. Drinking pure water without replacing the salt-loss aggravates the deficiency.

(Ref: T. K. Indrani/1/52)

Excess consumption of NaCl causes:

• Increases blood pressure in hypertension patients
• Oedema

Sodium chloride intake and excretion:

1. A healthy adult excretes daily in urine about 10-15 gm sodium chloride.
2. All this is derived from the salt taken in food.
3. Sodium chloride is also excreted in sweat.
4. During excessive sweating in hot climates, while doing hard work, the loss of sodium
chloride in sweat may vary from 10-20 gm daily.
5. During fasting or on salt free diets, the excretion of chlorides in urine may be decreased and only a trace of sodium chloride may be found.
6. Absence of sodium chloride in urine is an indication for adding more sodium chloride to the diet.
7. Sodium chloride is stored in the subcutaneous tissue.
8. During sodium chloride deprivation, the store is used up.

(Ref: T. K. Indrani/1/52

Requirement of sodium chloride:
Sodium chloride requirements depend on the climate and occupation. Foods of animal origin contain more sodium chloride than those of vegetable origin.

POTASSIUM

Potassium (K+):
Potassium (K+) constitutes an important cation of the body. Most of the potassium is present in the intracellular fluid within the cells. The normal potassium (K) ion of the blood plasma is 5 mEq/liter on the average human body is very sensitive to the alteration of the blood potassium level.

The adult human contains about 250 gm potassium which is present almost entirely in the cells of different tissues, muscle etc. Ninety percent of the potassium is present in cells of various tissues and RBCs. Potassium is absorbed from the gastrointestinal tract. Excess potassium is excreted in the urine.

(Ref: Essential of Human Nutrition/1/40)

Sources of potassium:
High sources of potassium is found in-

1. Whole grain
2. Bread
3. Dried-skimmed milk,
4. Instant coffee.
5. Cocoa
6. Fish.
7. Meat.
8. Fruits
9. Vegetables
10. Legumes and brain.

Functions of potassium:

Sources of potassium:
High sources of potassium is found in-

1. Potassium regulates acid-balance in the cell and helps in growth and development of tissue cells.
2. Potassium is required for the synthesis of glycogen
3. Cellular excitability of smooth muscles, skeletal, cardiac and nervous tissues occur in presence of potassium.
4. For the control of involuntary muscular functions potassium is required
5. It is essential for growth and building of tissues.

Deficiency diseases of potassium:

1. Weakness.
2. Muscular paralysis.
3. In animals, hypertrophy of the heart has been observed.
4. Hypokalaemia.

Hypokalaemia:
This condition occurs due to deficient intake of potassium or during excessive loss of potassium through gastrointestinal tract due to persistent vomiting or diarrhoea.

Clinical features:
The characteristic clinical features of Hypokalaemia are as follows:

• Fatigue.
• Muscular weakness.
• Cramps are common with moderate degree of low potassium

MAGNESIUM

Magnesium (Mg):
The adult human body contains about 25 gm of magnesium. In the human body magnesium is found distributed in bones, cells and extracellular fluid. The ionic magnesium (Mg++) present in blood is about 2 to 3 mEq/litre. Magnesium is derived from the dietary food in the small intestine. Vitamin D deficiency impairs magnesium absorption from the intestine. Its elimination from the body occurs in stools and urine. The average daily requirement for an adult is 30 mg per day. The rich natural sources are cereals and green vegetables. Excess magnesium is excreted in the faeces.

(Ref: Essential of Human Nutrition/1/54)

Functions of magnesium:

1. Magnesium is essential for all living cells. In plants magnesium is present in chlorophyll.
2. It is required as a co-factor for oxidative phosphorylation.
3. For the metabolism of calcium, potassium and formation of bones and tissue cell health magnesium is required.
4. Magnesium is combination with sodium, calcium and potassium is needed for the maintenance of balance in extracellular fluid for the transmission of nerve impulse and
the consequent muscle contraction.
5. Magnesium is required for protein synthesis.
6. It is found in certain enzymes, e.g. Co carboxylase which decarboxylates pyruvic acid.

Deficiency of magnesium:
Deficiency of magnesium occurs in-

1. Chronic alcoholics.
2. Cirrhosis of liver.
3. Toxaemias of pregnancy.
4. Protein caloric malnutrition
5. Malabsorption syndrome.
6. Neuromuscular irritability.
7. Tremors.
8. Cramps.
9. Tetany.
10. Hyperflexia.
11. Twitching.
12. Convulsion.
13. Confusion.
14. Visual hallucination and
15. Disorientation.

(Ref: Onila Salin’s Essential nutrition/1″/37)

Daily requirement of magnesium:

• Adult: 200-300 mg/day
• Older children: 150-200 mg/day
• Infants and pre-school children: 100-150 mg/day

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