Role of a macro mineral -Calcium in human body

1. CALCIUM
PRESENTED BY :
SANJALI EKATPURE
MSc
Symbiosis School of Biological Sciences

2.  CALCIUM :
 Symbol: Ca
 Atomic number: 20
 Atomic weight: 40
 History: It was in 1808, a British scientist Sir
Humphry Davy isolated calcium from a
mixture of lime and mercuric oxide.
 Applications: used in food preservatives,
cement, paints, insecticides etc.

3. Introduction -
calcium is a major mineral in human body.
 Almost 99% of calcium is present in the hard
tissues of the body –namely the bones and
teeth.
 The rest is distributed in blood and soft tissues ,
such as muscles , the liver and the heart.
 Normal blood plasma calcium is 9 – 11mg/dl.
 Calcium is stored in the form of hydroxyapatite
Ca10[PO4]6[OH]2.
 Men accumulate more skeletal calcium
[1200mg] than women [1000mg].

4. Functions :
 BONE FORMATION : calcium comprises 39.9 %
of the weight of bone mineral .there is about
1kg of calcium in the adult skeleton as a
complex crystalline material with phosphate
.the mineral is laid down on an organic matrix
– collagen.
 There are two types of bones –dense cortical
bone [80%of skeleton ] and spongy trabecular
bone [20%of skeleton ].
 The turnover of bone is controlled by the
activities of its bone cells –
 1 Osteoclasts – resorption of bone.
 2 osteoblasts – bone formation.
 3 osteocytes – communication with each other.
 Skeleton is constantly being resorbed and
replaced.
 The peak bone mass is achieved during 18 -20
yrs. of age.

5. Tooth formation: The enamel and dentine of tooth contain
calcium in the form of hudroxyapatite . These crystals are dense in
teeth than bones ,present along a protein called keratin.
The calcification of deciduous teeth begins by the time fetus is 20
weeks old and is completed shortly before they erupt at about 6
months.
Growth: Important part of bones, teeth and normal functioning of
every cell in the body.
Cofactor and regulator of biochemical reactions :
1.Blood clotting – It catalyses the conversion of the protein
prothrombin into thrombin which acts as an enzyme for formation
of insoluble blood clot.

6. 2. Contraction of muscles – Free calcium ions are released by the
initiation of nerve impulses . This is the internal trigger which leads to
shortening of myofibrils and so to contraction of muscles .
3. Calcium as intracellular messenger – It acts as a second
messenger for action of hormones e.g. epinephrine in liver
glycogenolysis.
4. Release of hormones – It facilitates the release of hormones like
insulin ,PTH and calcitonin.
5. Action on heart – it acts on myocardium and prolongs systole .
6. Membrane integrity and permeability – Calcium influences the
membrane structure and transport of water and several ions across it .
7. Activation of enzymes- such as pancreatic lipase ,ATPase and
succinate dehydrogenase .

7. ABSORPTION :
Calcium is absorbed by two distinct mechanisms, passive and active .
1 The active process requires energy stored within ATP, presence of
vitamin D and a mediator protein – calbindin.
2 It is more efficient in the duodenum and proximal jejunum where
the PH is more acidic. However absorption is greater in the ileum
where the residual time is greatest.
3 The passive process is a simple diffusion of calcium down its
concentration gradient ,requiring no energy expenditure.
4 30 -40 % of dietary calcium is absorbed by adults. Growing
children, pregnant and lactating women absorb 50-60% of calcium.
5 Estrogen enhances calcium absorption and hence absorption
declines after menopause.

8. FACTORS AFFECTING CALCIUM ABSORPTION
VITAMIN
D
Acidity
of
digestive
mass
LactoseProtein and
phosphorus.
Need for
calcium

9. Factors inhibiting calcium absorption :
*
• Oxalic acid
• Phytic acid
*
• Steatorrhoea
• Emotional instability
*
• Increased gastrointestinal motility.
• Lack of exercise
• Ageing
*
• Caffeine
• Drugs

10. Metabolism
Once calcium is absorbed , it is transported to the blood and released
into the fluids of body tissues. This is taken up by cells from the
extracellular fluid.
As blood is filtered through kidneys about 99% of calcium is
reabsorbed into blood. 1% excreted in urine [normally 100-200mg
/day]
Hormonal control : The balance of calcium is controlled by the
action of parathyroid hormone,1,25,dihydroxy cholecalciferol and
calcitonin.
Parathyroid hormone –decreased plasma free calcium triggers the
release of parathyroid hormone. It helps in many ways in maintaining
normal calcium levels.

11. Plasma calcium
Parathyroid
Bone resorption
Carbonic acid to
dissolute the bone
Calcium
absorption
Parathormone
Intestinal wall liver
Kidney
Phosphate
execretion
Ionic phosphate
absorption
Active form of
vitamin D
1,25(OH)2 D3
Reabsorption
of calcium
1,25, DHCC

12. Calcitonin - Elevated plasma calcium levels ,release calcitonin
from the thyroid glands. It inhibits the release of calcium and
phosphorus into the blood from bones.
Vitamin D - In calcium deficiency, the most active form of vitamin
D – 1-25,[OH]2 D3 causes enhanced intestinal absorption and renal
reabsorption.
Cytokines - May have a central role in normal bone remodeling.

13. Plasma calcium
Thyroid
Calcitonin
Bone
Calcium and phosphorus resorbtion
Formation of bone
Blood
Plasma calcium

14. Abnormality :-
Osteoporosis
It is a condition associated with loss in bone density and bone mass,
primarily found in middle age and elderly women .
According to NIN studies, women of low socio-economic group have
thinner bones due to their poor nutritional status and poor reproductive
health.
Risk factors- gender, body size, family history, disease, effect of drugs,
alcohol, smoking, sedentary lifestyle, inappropriate diet etc.
Diagnosis – duel energy X –ray absorptiometer [DEXA] measures the
bone density.
The test is not expensive and not invasive.

16. BONE DISORDERS :
Children with vitamin D deficiency develop rickets ,and adults
osteomalecia.
They do not calcify bone normally and their bones contain
osteoid [unmineralised bone].
HYPOCALCEMIA : When ionic calcium is reduced ,nerve and
muscles become readily excitable leading to a clinical condition
– TETANY.
Also associated with premenstrual syndrome – low calcium diets
exhibit increased negative effects ,greater pain ,more water
retention and poorer concentration.
Recent studies show that low calcium intake [100mg/day] is
associated with increased blood pressure.

17. HYPERCALCEMIA :
Elevated plasma calcium levels occur in adults due to
hyperparathyroidism or excessive doses of vit D. Gastrointestinal
symptoms like anorexia, nausea, vomiting, constipation,
abdominal pain occur.
Hardening of soft tissues especially of kidneys is fatal .
BIOCHEMICAL TESTS FOR CALCIUM DETECTION :
1 Plasma calcium level
2 vitamin D level
3 Recent studies by cardiologists suggest coronary calcium scans,
to check calcium in arteries of heart .It looks for calcium in
plaques of the coronary artery [cardiac calcium score ].

18. Effect of weight bearing exercise on bone
 Exercise
 Walking 1 mile /day
with vit D
supplement .
 running , aerobic
dancing , brisk
walking 300 min
/week
 Walking , aerobic
dancing 60 min -3
times / week
 Walking , jogging ,
stair climbing .
 effect
 Whole body BMD

 lumbar BMD
 Spinal BMD
stabilized
 Lumbar
BMD

19. ICMR – RDA’s for calcium - 2010
Group
 Man
 Woman
 Pregnant woman
 Lactating woman
 Infants 0-12 months
 Children 1-9 years
 Boys and girls 10 -
17 years
Calcium / day
 600
 600
 1200
 1200
 500
 600
 800

21. SOURCES
CALCIUM is present in both animal and plant foods.
Milk is the best source of calcium. Vit D, lactose and the ratio of
1.2 : 1 for ca : p, makes it most favorable for bone formation .
Other sources include whole and skim milk powder ,cheese and
crabs .
Green leafy vegetables like amaranth , fenugreek , drumstick
leaves , colocasia leaves are good sources of calcium . But their
content of iron competes for site of absorption in the intestine .
Most cereals and pulses contain some calcium –ragi being
exceptionally rich source of calcium .

22. Sources of calcium
RICH SOURCES
 JAGGERY 1638
 POPPY SEEDS 1584
 SESAME SEEDS 1450
 SKIMMED MILK
POWDER 1370
 CHEESE 792
 CAULIFLOWER
GREENS 626
 DRUMSTICK LEAVES
440
 RAGI 344
 BENGAL GRAM
LEAVES 340
 BUFFALO MILK 210
 CURDS 149
 COW’S MILK 120

23. RECENT HEALTH PROBLEMS IN INDIA :
Include maternal and neonatal morbidity and mortality due to
calcium deficiency
preeclampsia [low socioeconomic group]
Osteoporosis in elderly women.
Hypertension and cardiac disorders.
SUPPLEMENTS : are prescribed for women above the age of
40 yrs. [along with exercise ], men above 55yrs and pregnant
and lactating women.
NATIONAL INSTISTUTE OF HEALTH suggests not more
than 600 mg calcium supplement per day along with meals.
Different combinations are used depending upon health
conditions – calcium carbonate, calcium citrate, calcium
phosphate, calcium lactate etc.
If any iron or thyroxin supplements are taken , calcium
supplements to deliberately be taken separately.

24. References :
1. who.guideline.calcium supplementation .
2. httpl//india.gov.in
3’ Jim Mann and A.Stewart Truswell ,Essentials of human
nutrition , third edition.
4. Krause “s Food and nutrition care process ,13th edition
5. B Srilaxmi, Nutrition science, fifth edition.

25. Decreased blood calcium level Increased blood calcium level
Intestine BoneBone
Normal blood calcium level
Parathyroid Kidney Thyroid
Parathormone 1,25-Dihydroxy-
cholecalciferol Calcitonin
Resortion and
release of calcium
Absorption of
calcium
Deposition of calcium