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.
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 is a compound made up
of calcium and phosphate that is deposited into the bone matrix to give it
strength and rigidity.
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.
Tooth formation: - Calcium and
Phosphorous together as a compound is essential for the formation of dentin and
Physiological Process: -
Calcium is essential for the
clotting of blood as it is required for prothrombin activation.
Calcium regulates the permeability
of the capillary walls and ion transport across the cell membranes.
It is essential for the contraction
of the heart and skeletal muscle.
Ca regulates the excitability of the
Ca acts as an activator for enzymes
such as rennin and pancreatic lipase.
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.
In the DNA and RNA phosphate is an
essential part of the nucleic acids.
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.
The recommended dietary allowances for Calcium, as suggested
by the ICMR is given in table-21A.
Calcium related health problems
occur due to inadequate intake, improper absorption or utilization of calcium.
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:
Prolonged dietary inadequacy
2. Poor absorption and utilization of calcium
4. Decreased levels of oestrogen in post menopausal women.
5. Hyper parathyroidism
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 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 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.
The total body iron is 4g in adults.
Iron exists in a complex form in our body. It is present as
Iron porphyrin compounds -
hemoglobin in RBC, myoglobin in muscle.
Enzymes - (eg) peroxidases,
succinase dehydrogenase and cytochrome oxidase.
Transport and storage forms: - (eg)
transferrin and ferritin.
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
Conversion of beta carotene to
active form of Vitamin A
Synthesis of carnitine, purines,
collagen and neuro transmiters.
Detoxification of drugs in the
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.
Iron requirements for various age groups is listed in
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
Reduced Haemoglobin level. (less
than 12 g /dl)
Defects in the structure, function
of the epithelial tissues
3. Paleness of skin and the inside of the lower eyelid is pale
Finger nails becoming thin and flat
and eventually (spoon shaped nails) koilonychia develops.
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 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.
Iodine is essential for the
synthesis of the thyroid hormones T3 and T4.
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.
The ICMR recommended dietary
allowance for Iodine is 150 µg/day.
Iodine deficiency in the diet,
causes enlargement of the thyroid gland called as 'goitre'. Goitre occurs in
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
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 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.
Zinc is a constituent of enzymes
such as carbonic anhydrase, alkaline phosphatase, lactic dehydrogenase.
2. It is a constitutent of the hormone insulin
It plays a major role in the
synthesis of DNA and proteins.
Meat, unmilled cereals and legumes
are good sources. Fruits and vegetables are poor sources.
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