1. Community Medicine Lecture -5-

2. Learning objectives
At the end of this lecture student would be able to :
1-Determine vitamins general characteristics .
2-Classify vitamins .
3-Determine essential facts about vitamins A,E,K & B complex .
4-Outline clinical presentation of vitamin A deficiency & toxicity .
5-Identify directions of action of vitamin D , clinical features of vitamin D deficiency .
6-Discuss clinical presentation of vitamins B1,B2,nicotinic acid , folic acid , B12 , & vitamin C deficiency .

3. Vitamins
Vitamins are group of organic compounds that are needed in small amounts for maintaining normal metabolism of nutrients and thus promoting the physiological well being of human body.
 It cannot be synthesized by human body.
 Vitamins vary in their composition and functions.
 Its presence in various kinds of food is in a variable amounts.
 No optimal food is present i.e. there is no food that contain all essential vitamins to satisfy the daily requirement .

4.  Vitamins are usually required in a relatively small quantities.
 Vitamins Primarily have a catalytic function i.e. it enter in the enzymatic system components which play an important role in facilitating essential metabolic reactions.

5. Causes of vitamin deficiency
A- Decreased intake including :
1- alcohol intake
2- small bowel diseases
B-Decreased absorption including :
1- disease due to liver or biliary tract
2- bacterial overgrowth in the intestine

6. Causes of vitamin deficiency/ cont
C- Miscellaneous including :
1- Renal diseases

7. Classification
According to its solubility , vitamins are classified in to :-
A-) Fat soluble vitamins
It include vitamins A,D,E and K.

8. Vitamin A (Retinol)
 Although vitamin A can be destroyed easily by oxidation ,it is relatively heat stable material.
 To a great extent , it is found naturally in its precursors form i.e. carotenoid pro-vitamins alpha, beta and gamma carotene . 
 Sources are liver , dairy products ,eggs ,green vegetables and carrot . Fish liver is the most concentrated natural source.

9. Importance of vitamin A
1.It is necessary for the growth of children.
2.It play an important role in the eyes perception to light specially at night (rods and cones photo receptors).
3.It has a protective function for surface tissues e.g. respiratory tract and eye (cornea).

10. Other effects of vitamin A
1- possible beneficial effects
A- protection against cancer
B- reduction in cardiovascular events
2- possible adverse effects:
1- retinol is a teratogenic

11. Vitamin A deficiency Clinically patient will develop:-
1.Night blindness i.e. poor adaptation for dark.
2.Xerosis i.e. changes in the outer layer of sclera resulting in xeropthalmia .
3.Keratomalacia i.e. corneal affection.
4.Cutaneous lesions around the hair follicles.
5.Epithelial changes .

12.  The daily recommended allowances is 5000 I.U.
Vitamin A toxicity
Patient clinically will have:-
1.Anorexia .
2.Dry itchy skin .
3.Coarse hair.
4.Swelling over the long bones.
 The daily recommended allowances is 5000 I.U.
 Additional daily requirement is 1000 I.U. for pregnant woman and 3000 I.U. for lactating woman.

13. Vitamin D
Vitamin D play a major role in increasing the utilization and retention of calcium and phosphorus in the body.
Directions of action:-
1.It increase the absorption of dietary calcium and phosphorus from intestinal lumen.
2.It reduce phosphorus excretion in urine through enhancing renal reabsorption of it .
3.It maintain proper calcium and phosphorus levels in blood .This will ensure normal mineralization condition for mature bones.

14.  In children leads to Rickets.  In adults leads to Osteomalacia.
Vitamin D deficiency

15. Thyroid hormones
Both parathyroid and calcitonin hormones with vitamin D are concerned with maintenance of calcium and phosphorus -plasma levels .
Sources are liver oil, fish ,egg ,milk and milk products.
During summer ,dairy products contain more vitamin D than during winter.
Sunlight act on skin and subcutaneous fat and help in the oxidation and formation of vitamin D.

16. Vitamin E It has some influence on fertility.
Sources are green vegetables, milk and milk products.
The main function of vitamin E are :
1- antioxidant properties
Vitamin E deficiency causing
1- hemolytic anemia

17. Vitamin K 1-It is found in green plants.
2-It Play a role in prothrombin formation Thus it is essential for normal clotting of blood.
3-Bacterial flora of intestine synthesize vitamin K.

18. Vitamin K deficiency
Vitamin K deficiency lead to defect in clotting factor synthesis and increase in prothrombin time resulting in hemorrhage
The deficiency occur in the following conditions :
1- The newborn baby due to poor placental transfer of vitamin K and its little amount present in breast milk
2- Cholestatic jaundice when there is an interruption of the bile flow into the intestine

19. Vitamins B complex (vitamins B group) Vitamin B1 (thiamine):-
Unstable at high temperature .
Destroyed by alkaline materials.
The main functions of vitamin B1are :
2- Thiamin pyrophosphate is involved in the oxidative decarboxylation of acetyl CoA in mitochondria
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20. Vitamin B1 deficiency usually presented as :
1.Affection of children growth.
2.Neuritis.
3.Irritability and depression (psychological symptoms)
4.Beriberi disease a- wet type (in cases of extreme deficiency)
b- dry type
Sources are seeds, green plants, potato and milk.

21. B1 deficiency Thiamin deficiency is seen :
1- As beriberi, where the only food consumed is polished rice .

22. Vitamin B2 (riboflavin)
It is easily destroyed by heat, ultraviolet and alkaline materials.
 Sources are liver, meat, eggs, and milk.
 Features of vitamin B2 deficiency are:-
1.Affection of children growth.
2.Cracks at corners of mouth and nose (Angular stomatitis )
3.Glossitis ( a red , inflamed tongue )

23. Nicotinic Acid Niacin is necessary for fatty – acid synthesis
Niacin is lost by removing bran from cereals .
Niacin is found in plants , meat ( mainly offal ) and fish .
Features of nicotinic acid deficiency are:
1. Affection of children growth .
2.Skin affection result in red rough skin.
3.Digestive disturbances and diarrhea.

24. Folic Acid Its deficiency lead to pernicious anemia.
Its deficiency result in macrocytic anemia.
Sources are liver, green vegetables and formed by intestinal flora.
Vitamin B12
Its deficiency lead to pernicious anemia.
Its minimal daily requirements is 0.1  gm.
Its liver store depleted in 3-6years.
Sources are liver, meat, milk, and fish.

25. Vitamin C It can be easily destroyed by heat.
 Its main sources are fruits, fresh vegetables ,fresh liver ,meat and milk.
Ascorbic acid is easily leached out of vegetables when they placed in water
Potatoes are a good source , but vitamin C is lost during storage .
A dose of 1-2g/ daily of ascorbic acid will prevent common cold

26.  Features of its deficiency include:-
1. Affection of children growth.
2.Bleeding around hair follicles. .

27. Vitamin B6
1- It is exists as pyridoxine which is found mainly in plant and animal foodstuffs .
2- Pyidoxal phosphate is a cofactor in the metabolism of many amino acids
3-Some drugs like (isoniazid and penicillamine) interact with Pyidoxal phosphate leading to B6 deficiency .

28. Thank You