3. VITAMINS

4. Definition
Vitamins are naturally occurring organic essential micronutrients present in very small quantity in diet ( from few microgram to mg) and needed for normal metabolism, development, function and optimal health.

5. Specific role played by vitamins now is confirmed that
Required for the execution of Metabolic functions
If deficient, certain specific metabolic disorders are seen.
Participate as coenzyme in various enzyme catalyzed reaction.
Vitamins do not provide energy.

6. DIETARY SOURCES
Mainly derived from food meat, fish, milk, vegetables, fruits
As Can not be synthesized in appropriate quantities, must be present in human diet.

7. Other Sources
Few are synthesized by normal intestinal flora ( Vitamin K and B 9)
Few others are synthesized by some body tissues like skin Vit-D

8. Functions (Contd.) Maintenance of optimal Health
Prevention of chronic diseases may require certain vitamins in amounts greater than RDA.
Normally 15 iu/day of vit E is required for health
100 iu of vit E is required for significant reduction in risk of CAD
It is also believed that vitamins play a role in prevention of Cancer.

9. Classification
14 different vitamins so far have been isolated and purified into crystalline form. These are classified in to two groups
Classification is based on solubility characteristics.

10. Requirements
Varies with metabolic activity Age, Size, Sex of an individual
Requirement increase during
Exercise
Fever
Disease
Pregnancy
Lactation

11. Requirements (Contd.)
Requirement of B, are particularly increased in CHO rich diet.
For every 1000 Calories obtained form carbohydrate rich diet 1mg of B1 is needed

12. Storage Water Soluble:
Not stored in our bodies. Must therefore be present in diet to an appreciable extent for normal health and growth.
Fat Soluble:
Are stored, if taken in excess. Stores are sufficient to meet the demand of our body for almost months, if no vitamins are taken through diet.

13. Wastage
During therapy and intestinal infection, drugs like sulfonamides and antibiotics kill the normal intestinal flora which synthesizes vit.of B complex group.
Demand increases, and Supplementation is advised

14. Wastage
Water soluble vitamins are lost when cooked in water and Specially when water is thrown away.
Vegetable should not be washed after cutting.
Milling and polishing of rice destroys B2.
Hydrogenation of oils, inactivates Vit A & D,and before marketing fortification with A & D be done.

15. Wastage
Water soluble vitamins are lost when cooked in water and Specially when water is thrown away.
Vegetable should not be washed after cutting.
Milling and polishing of rice destroys B2.
Hydrogenation of oils, inactivates Vit A & D, and before marketing fortification with A & D be done.

16. Vitamin D

17. Vitamin D is a group of fat-soluble Secosteroids.
In humans, vitamin D is unique
It functions as a hormone and
As the body can synthesize it (as vitamin D3) when sun exposure is adequate.

18. IS VIT D A VITAMIN ?
Although "vitamin D" is commonly called a vitamin , some say it should not be classified as a vitamin because it can be synthesized by the human body.

19. VIT . D AS VITAMIN
Vitamin D fits within the definition of vitamin as it is "an organic compound required as a vital nutrient in small amounts by an organism.
In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet".
Additionally, like other compounds called vitamins, in the developed world vitamin D is added to milk,ghee and oil, to avoid disease due to deficiency.

20. DISCOVERY
As with other compounds called vitamins, it was discovered in an effort to find the dietary substance that was lacking in a disease, namely, ricket, the childhood form of osteomalacia.

21. Vitamin D occurs in two forms:
“Vitamin D2” (ergocalciferol),
chief Vit D precursor in plants is, ergostreol.
2 “Vitamin D3” (cholecalciferol),
the main form occurring in animal cells and developing in skin on exposure to ultraviolet light from 7- dehydro cholesterol.

22. Animal sources of Vit D
Eggs
Liver
Butter
Fish

23. Absorption
Vit D is stable through storage, processing and cooking and is absorbed effectively from GIT
Any abnormality in fat absorption may cause mal- absorption of Vit D

24. Absorption and metabolism
Before it can function, Vit D3 must be activated by hydroxylation which takes place both in liver & kidney.
The initial conversion in the liver results in 25-hydroxy cholecalciferol (calcidiol), the major circulating form of Vit D3.

25. Absorption and metabolism
2nd hydroxylation takes place in the proximal tubule of the kidney, giving rise to 1,25-dihydroxycholecalciferol or calcitriol.
This form is then transported to bones, kidneys and intestines.

29. THANKS