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3. Definition
• “Substances distinct from major components of
food, required in minute quantities and whose
absence cause specific deficiency diseases”.

4. General characteristics of vitamins
1. Vitamins are widespread occurrence in nature, both in plant
and animal worlds.
2. The plants can synthesize all the vitamins whereas only few
vitamins are synthesized in the animals.
3. Human body can synthesize some vitamins, e.g., vitamin A.
4. Most of vitamins have been artificially synthesized.
5. Vitamins are partly destroyed and are partly excreted.
6. All the cells of body store vitamins to some extent.
7. Vitamins are nonantigenic.
8. Vitamins are effective when taken orally.
9. Vitamins carry out functions in very low concentrations.
10. Synthetically-made vitamins are just as nutritionally good
as natural vitamins.

5. Vitamin Classification
• Fat-soluble vitamins
– Dissolve in substances such as ether and benzene
but not readily in water
– Include vitamins A, D, E, and K
• Water-soluble vitamins
– Vitamins that dissolve in water
– Include B vitamins and vitamin C

6. • The sunshine vitamin.
• Fat soluble vitamin.
• Is often called antirachitic factor in food.
• Resemble sterols in structure and function like
a hormone.
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7.  2 sources
• - 90% synthesised in skin via UVB light exposure
• - Cholecalciferol (vitD3 = inactive)
• - 10% from food – Ergocalciferol (vit D2=
inactive)
 Activation in liver and kidneys to CALCITRIOL.

8. History
Work Scientists Years
Discovered by Mellanby 1919
First Demonstrated
Elmer McCollum 1922
its existence
Discovered its
chemical nature
H. Steenbock and
A.F. Hess
1924
Isolated and named
as calciferol
Augus 1931

9. Properties of Vitamin D
• Vitamin D is a white and odourless crystalline
substance.
• It is fairly heat resistant.
• Relatively resistant to oxidation.
• It is not affected by acids and alkalies.
• Vitamin D in foods and in food concentrates is not
easily destroyed by heating.

10. Structure of Vitamin D

11. Rich dietary sources of Vitamin D
• The best natural sources of vitamin
D are the liver oils of many fishes
as cod and halibut.
• Egg yolk is fair good source of
vitamin D.
• Vitamin D2 plant origin.
• Vitamin D3 is the animal origin and
can be produced from 7-
dehydrocholestarol is also by
irradiating with UV light.

12. Vitamin D can be provided to the body in
three ways:
1. Consumption of natural foods.
2. By irradiating foods (like yeast) that contain precursors of
vitamin D and fortification of foods (milk, butter etc.)
3. Exposure of skin to sunlight for synthesis of vitamin D.

13. Rich sources of Vitamin D per 100 g of
edible portions
Fish and poultry Mcg
Cod-liver oil 175
Shark-liver oil 50
Halibut-liver oil 5-100
Eggs 1.5
Ghee 2.5
Butter 1.0
Note: Sunlight is the most important source of this vitamin.

14. Deficiency symptoms of Vitamin D
• Vitamin D deficiency occurs in strict vegetarians,
chronic alcoholics, individuals with liver and
kidney diseases or fat malabsorption syndromes.
• Deficiency of vitamin D leads to mineralization of
bone.
• Rickets is a primarily a disease of growing bones.
• A study conducted by the Indian Social Institute,
New Delhi (1981) shows that about 168 children
per 1000 of live births die of rickets in India.

15. Osteomalacia
• The bones become softer than the rachitic bones
and the C/P ratio does not remain constant.
• The disease is prevalent in India, China & Arab,
particularly among women because of custom that
keeps them indoor and also prevents them from
exposure to sun.

16. Idiopathic Steatorrhea or Celiac Disease
• This is like osteomalacia.
• The disease is characterised by demineralization of
the bones which may result in dwarfism.
• In fact, Celiac Disease is indirectly a vitamin d
deficiency.
• The fat is not absorbed in the intestine and is passed
out in stools along with calcium salts and vitamin D.

17. Demineralization of Bone
• Overdosing of calciferol to the children and adults as
well produces Demineralization of Bone.
• Serum concentrations of both calcium and phosphate
are greatly raised, resulting in metabolic calcification
of many soft tissues and the formation of renal
calculi.
• The latter disorder may block the renal tubules
causing hydronephrosis.

18. Hypoparathyroidism
• Deficiency of parathyroid hormone (PTH) results
in hypocalcemin and hyperphosphatemia.
• Lack of vitamin D may lead to teeth decay,
pyorrhea, brittle or soft bones, retarded growth,
and poor bone formation in children.
• It may causes muscular weakness, lack of vigour,
deficient assimilation of minerals, and premature
ageing.
• Lack of this vitamin in children can also give rise
to improper activity of parathyroid gland, and
result in convulsions.

19. Metabolic and Biochemical functions
• The provitamin D3 can be synthesised within
the human body.
• The increased need of this vitamin D is usually
felt in growth and in pregnancy to provide for
the needs of foetus.
• Vitamin D plays an important role in
calcification of bones and teeth.
• It encourages the absorption of calcium and
phosphate salts.
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20. • Vitamin D2 and D3 as such are not biologically
active.
• They are metabolised identically in the body
and converted in active forms of vitamin D.
• Calcitrol is the biologically active form of
vitamin D, it regulates the plasma levels of
calcium and phosphate.
• Calcitrol acts at 3 levels (intestine, kidney and
bone) to maintain plasma calcium.

21. Healing and Therapeutic properties
1. Rickets
 Vitamin D plays a very important role in the
prevention and treatment of rickets.
 The therapeutic dose varies from25 to 125
mcg per day, depending on the severity of
the disease.

22. 2. Renal Rickets (Renal
osteodystrophy)
• This is in patients with chronic renal failure.
• Renal Rickets is mainly clue to decreased
synthesis of calcitriol in kidney.
• It can be treated by administration of calcitriol.

23. 3. Bone Repair
• Any excess of calcium stored in the long bones
serves as reserve for bone repair when needed.
• Vitamin D also contributes substantially towards
bone repair by increasing calcium absorption
through the intestinal wall
• This vitamin also regulates the deposition of
minerals in bones and teeth.

24. 4. Tooth Decay
• Vitamin D has been found beneficial in the
treatment of tooth Decay.
• Mellanby proved the importance of this
vitamin for tooth nutrition in children.

25. 5. Arthritis
• Vitamin D is considered extremely beneficial in
the treatment of arthritis.
• It needs to be taken with calcium for the body to
be able to utilise it efficiently.

26. RECOMMENDED DIETARY ALLOWANCE
• The daily requirement of vitamin D is 400 IU or 10 mcg
of cholecalciferol.
• In countries with good sunlight (like India), the RDA for
vitamin D is 200 IU (or 5 mcg cholecalciferol).
• For older people, pregnant women and lactating mothers
400 units are adequate.
• Vitamin D requirement is greatly influenced by the
amount of ultraviolet light to which the individual is
exposed.
• For adults exposure to sunlight for 30 minutes a day is
believed to satisfy the daily requirement (about 10 mcg)
of vitamin D.

27. Precautions
• Dosage of over 125 mcg taken daily may adversely affect
some individuals.
• Abnormal calcium deposits may also be foud in the
blood-vesselwalls, liver, lungs, kidneys, and stomach.