Functions, Food Sources, Requirements And Effects Of Deficiency Of All Minerals

Until the middle of the nineteenth century, the importance of minerals and vitamins was not known. It was observed that carbohydrate, fat, protein alone were incapable of promoting and sustaining growth.

Hence scientists attempted to find out the 'missing elements', namely minerals and vitamins which are essential for growth and maintenance.

Essential minerals which are inorganic substances are classified as macro and micronutrients based on the amount needed by humans per day.

Macrominerals are those which are vital to health and that are required in the diet by more than 100mg per day and those required in the diet less than 20mg per day are called microminerals or trace minerals.

The essential microminerals are Calcium, Phosphorous, Magnesium, Sulphur, Potassium and Chloride. Important microminerals of relevance in human nutrition are Iron, Zinc, Copper, Sodium, Cobalt, Fluoride, Manganese, Chromium, Iodine and Molybdenum.

FUNCTIONS, FOOD SOURCES, REQUIREMENTS AND EFFECTS OF DEFICIENCY OF ALL MINERALS.

Calcium and Phosphorus:

Calcium is an essential element required for several life processes. The requirements of Calcium and Phosphorous are considered together as their function and requirement are closely linked.

Over 99% of the Calcium and Phosphorous is present in the bones and the remaining 1% in the body fluids.

The Calcium and Phosphorous are present in the ratio of 2:1 in our body. In the skeletal system Ca and P is present in the form of hydroxyapatite crystals.

Hydroxyapatite is a compound made up of calcium and phosphate that is deposited into the bone matrix to give it strength and rigidity.

Functions :

1.     Bone formation:

a.     The major mineral ions of the bone are Calcium, Phosphorous and Magnesium. For proper calcification of bones, (deposition of minerals on the bone matrix) which occurs during the growing years, adequate supply of these minerals is essential.

2.     Tooth formation: - Calcium and Phosphorous together as a compound is essential for the formation of dentin and enamel.

3.     Physiological Process: -

a.     Calcium is essential for the clotting of blood as it is required for prothrombin activation.

b.     Calcium regulates the permeability of the capillary walls and ion transport across the cell membranes.

c.      It is essential for the contraction of the heart and skeletal muscle.

d.     Ca regulates the excitability of the nerve fibres.

e.      Ca acts as an activator for enzymes such as rennin and pancreatic lipase.

4.     Phosphorous is essential for the storage and release of adenosine triphosphate (ATP) molecules.

5.     Phosphates plays an important role as buffers to prevent changes in acidity of the body fluids.

6.     Phoshpolipids are major components of cell membrane and intra cellular organelles.

7.     In the DNA and RNA phosphate is an essential part of the nucleic acids.

Food sources

Among cereals ragi contains large amounts of calcium. Bengalgram whole, gingely seeds, cuminseeds, poppy seeds, agathi, amaranth, drumstick leaves are good sources of calcium. Milk and milk products are good sources of calcium and phosphorous. Only 20 - 30 % of the calcium in the diet is absorbed, which is facilitated by Vitamin - D. All foods contain significant amounts of phosphorous.

Requirements

The recommended dietary allowances for Calcium, as suggested by the ICMR is given in table-21A.

Deficiency

Calcium related health problems occur due to inadequate intake, improper absorption or utilization of calcium.

Osteoporosis:

Osteoporosis is a condition found primarily among middle aged and elderly woman, where the bone mass of the skeleton is diminished.

It is a condition of multiple origin. It results due to the following reasons:

1.     Prolonged dietary inadequacy

2.     Poor absorption and utilization of calcium

3.     Immobility

4.     Decreased levels of oestrogen in post menopausal women.

5.     Hyper parathyroidism

6.     Vitamin - D deficiency

Osteomalacia - is a condition in which the quality but not the quantity of bone is reduced. This condition is dicussed in detail under deficiency of Vitamin - D.

Tetany

Tetany occurs when Calcium in the blood drops below the critical level. There is a change in the stimulation of nerve cells resulting in increased excitability of the nerve and uncontrolled contraction of the muscle tissue. Hence Calcium and Phosphorous ratio in the diet should be maintained at 1:1 for proper utilization of Calcium in the body.

Microminerals

Microminerals are also known as trace elements. The microminerals are Iron, Iodine, Zinc, Copper, Fluoride, Selenium, Chromium, Manganese, cobalt and Molybdenum. However only the deficiency of few of these elements is observed in humans. Iron and Iodine deficiencies are wide spread while deficiency of Cu, Zn, Cr and Se have been reported in recent years.

Iron

The total body iron is 4g in adults. Iron exists in a complex form in our body. It is present as

1.     Iron porphyrin compounds - hemoglobin in RBC, myoglobin in muscle.

2.     Enzymes - (eg) peroxidases, succinase dehydrogenase and cytochrome oxidase.

3.   Transport and storage forms: - (eg) transferrin and ferritin.

Functions :

The chief functions of iron in the body are :

1.     Iron forms a part of the protein - haemoglobin which carries oxygen to different parts of the body.

2.     It forms a part of the myoglobin in muscles which makes oxygen available for muscle contraction.

3.     Iron is necessary for the utilization of energy as part of the cells metabolic machinery.

4.     As part of enzymes iron catalizes many important reactions in the body. Examples are

a.     Conversion of beta carotene to active form of Vitamin A

b.     Synthesis of carnitine, purines, collagen and neuro transmiters.

c.      Detoxification of drugs in the liver.

Food Sources

The iron present in food can be as haem and non-haem iron depending upon the source from which it is obtained. Haem iron - is obtained from animal tissues, non-heam iron - is obtained from plant foods.

Sources of non-haem iron are ragi, green leafy vegetables, dried fruits and jaggery. Liver, fish, poultry, meat, eggs dates are good sources of haem iron .

Haem iron is absorbed and utilized better than the non-haem iron. Iron absorption from Indian diets is only 3 percent as it is mainly cereal based diet.

Requirement

Iron requirements for various age groups is listed in table-21B.

Deficiency

Dietary iron deficiency leads to nutritional anaemia. Nutritional anaemia is defined as the condition that results from the inability of the erythropoetic tissue to maintain a normal haemoglobin concentration.

Anaemia occurs when the haemoglobin level falls below 12 gm /dl in adult man and woman. During pregnancy haemoglobin level below 11 gm /dl is termed anaemia.

Nutritional anaemia is the common form of anaemia affecting women in reproductive years, infants and children which is mainly due to poor intake and absorption.

Iron deficiency anaemia is wide spread in our country. The prevalence varying from 45% in men and 70% in women and children. The major cause of anemia in India is because of Iron and folic acid deficiency.

Nutritional anemia is manifested as :

1.     Reduced Haemoglobin level. (less than 12 g /dl)

2.     Defects in the structure, function of the epithelial tissues

3.     Paleness of skin and the inside of the lower eyelid is pale pink

4.     Finger nails becoming thin and flat and eventually (spoon shaped nails) koilonychia develops.

5.     Progressive untreated anaemia results in cardiovascular and respiratory changes leading to cardiac failure. The general symptoms include lassitude, fatigue, breathlessness on exertion, palpitations, dizziness, sleeplessness, dimmness of vision, and increased susceptibility to infection.

Iodine

Iodine is an essential constituent of the thyroid hormone produced by the thyroid glands. It occurs as free iodide ions or as protein bound iodine in our body. About 15 - 23 mg of iodine is present in the adult human body.

The body store of iodine is predominantly present in thyroid gland and also in salivary gland, mammary glands gastric glands and in kidneys to a certain extent.

Function

Iodine is essential for the synthesis of the thyroid hormones T₃ and T₄.

Sources

Richest source of iodine are sea foods like sea fishes and common salt from sea water. Iodine content of vegetables, fruits and cereals depends upon the iodine content of the soil in which they grow. The soil of mountaineous regions contains less iodine.

Requirement

The ICMR recommended dietary allowance for Iodine is 150 µg/day.

Deficiency

Iodine deficiency in the diet, causes enlargement of the thyroid gland called as 'goitre'. Goitre occurs in people staying

in hilly regions where the iodine content of water and soil is comparatively less.

In India goitre is common in hilly districts of Himalaya. Goitre can be treated by administration of iodine. If treatment is given in early stages goitre can be corrected.

Severe iodine deficiency in children leads to hypothyroidism resulting in retarded physical and mental growth. This condition is known as cretinism.

Goitrogens are substances present in foods which cause goitre. These substances react with iodine present in the food making it unavailable for absorption. Foods like cabbage, cauliflower, raddish contain goitrogens.

Zinc

Zinc is primarily intracellular substance. Its total quantity in the body is 2.3g. Largest stores of Zinc is present in the bones. Zinc forms a constituent of the blood. Zinc is an important element performing a range of function in the body as it is a cofactor for a number of enzymes.

Functions

1.     Zinc is a constituent of enzymes such as carbonic anhydrase, alkaline phosphatase, lactic dehydrogenase.

2.     It is a constitutent of the hormone insulin

3.     It plays a major role in the synthesis of DNA and proteins.

Sources

Meat, unmilled cereals and legumes are good sources. Fruits and vegetables are poor sources.

Requirements

The daily requirement of Zinc in adults is 15.5 mg / day as recommended by the ICMR expert group.

Apart from iron, iodine, zinc, copper, selenium and fluorine are essential trace elements. Copper is essential element in iron absorption.

Selenium is an essential element along with Vitamin E for maintaining integrity of the liver cells. Fluorine is required in minimum amounts to prevent dental caries. Excessive consumption leads to mottling of teeth.