VITAMINS

2. VITAMINS

3. Definition Vitamins are naturally occurring organic compounds, present in very small quantity in diet and which are essential for normal health.

4. Later on it was concluded that • Normalmetabolic functions cannot be executed without these compounds • If deficient, certain specific metabolic disorders are seen. • Participate as coenzyme in various enzyme catalyzed reaction. • Vitamins do not provide energy.

5. DIETARY SOURCES • Mainly derived from foodmeat, fish, milk, vegetables, fruits • As Can not be synthesized in appropriate quantities, must be present in human diet.

6. Other Sources • Few are synthesized by normal intestinal flora • Few others are synthesized by some body tissues like skin ---------- Vit-D

7. 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.

8. 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.

9. Requirements • Varies with metabolic activityAge, Size, Sex of an individual • Requirement increase during • Exercise • Fever • Disease • Pregnancy • Lactation

10. 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

11. 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 6 months, if no vitamins are taken through diet.

12. 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

13. 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.

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. Vitamin A • Vitamin A is an important fat soluble vitamin required for growth and normal eye function

16. Sources • Major sources of vit A are the carotenes , synthesized by plants • Animals including humans can convert carotenes in plants to Vit A. • Alpha, beta and gamma carotene are of nutritional importance.

17. Chemical Structure

18. Sources • Alpha and gamma carotenes yield 1 molecule of Vit A • Beta carotene yields 2 molecules of vit A upon hydrolysis • Vitamin A is present in 2 forms in diet • Preformed Vit A (retinol) • Provitamin A carotenoid (Vitamin A precursors).

19. Animal sources Fish Olive oil Milk Butter Cheese Liver Eggs Vegetable sources Deep green & yellow plants Carrots Turnip Dietary sources

20. Absorption and Metabolism • Absorption occurs in the intestine Activation: To be active, • Pro vitamins A, carotenoids must be converted into retinol during absorption. • Hydrolysis of carotenes occurs in the mucosa of small intestine.

21. Absorption • Absorption of Vit A is facilitated by dietary fat, bile, thyroid hormone and Vit E. • Mineral oil prevents the absorption of Vit A • Vit A is also absorbed directly into portal circulation and transported in chylomicrons • Enters the blood circulation and reach the liver.

22. Functions In the retina of the eye there are two types of light receptors • Cones for vision in bright light & color vision • Rods for vision in dim light The photo sensitive receptors (Rhodopsin visual purple in rods and Iodopsin or visual violet in cones) contains Vit A plus different proteins. When struck by light the pigments are split apart into Vit A and the constituent protein.

23. Mucous Membranes • Vit A is involved in the synthesis of mucoproteins and mucopolysaccharides. • The integrity of the epithelium, particularly the membranes of the genitourinary , respiratory and GI tract, eyes and mouth are maintained by mucous secretions.

24. Recommended Dietary Allowances Infants 0 – 0.5 420 g 0.5 – 1.0 400 g Children 1 – 3 400 g 4 – 6 500 g 7 – 10 700 g

25. Recommended dietary allowances AdultsMale Female 11 – 14 1000 800 15 – 18 1000 800 19 – 22 1000 800 23 – 50 1000 800 51+ 1000 800 Pregnancy + 200 Lactation + 400

26. Recommended dietary allowances • The allowances for children and adolescents are based on average body weight and growth needs. • Adults Males RDA is 1000 retinol equivalents(5000iu) • Adults Female RDA is 800 retinal equivalents (4000 iu) • In pregnancy and Lactation it is increased to 1000 and 1200 retinal equivalents respectively. • Vit A is stored in liver and normal individuals have a three month supply

27. Deficiency Disease The deficiency may be due to • Poor intake • Incomplete absorption and metabolism (chronic diarrhea and use of mineral oils) • Abnormal fat metabolism (pancreatic disease) • Hepatic diseases

28. Effects • Night blindness (nyctalopia) • Inability to see well in dim light when entering a dark space form bright light • Night blindness occurs when there is insufficient Vit A in the blood to quickly regenerate visual purple . 4. Alcoholic liver disease (cirrhosis) causes night blindness which is due to hepatic damage affecting Vit A release.

29. Effects • In the eye, the 1st symptom of Vit A deficiency include photophobia (sensitivity to bright light) • Inflammation of eyes and eyelids due to impaired functioning of lacrimal glands • Xerophthalmia (dry, inflamed and edematous cornea) • Keratomalcia – permanent blindness results when infection leads to ulceration and softening of cornea

30. Skin and mucous membrane changes • Keritinization of the epithelial tissues • Increase susceptibility to infections of all membranes, protected by mucous • Follicular hyperkeratosis – The sebceous glands becomes clogged and skin takes on a gooseflesh like appearance.

31. Toxic effects • Drying and desquamation of skin • Anorexia • Loss of hair • Bone pain and fragility • Enlargement of liver and spleen

32. Vitamin D

33. Vitamin D Vitamin D occurs in two forms, as • “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- dehydrocholesterol

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

35. Animal sources of Vit D • Eggs • Liver • Butter • Fish

36. Absorption and metabolism Vitamin D3 is obtained from two sources: • Vit D3 is obtained from diet or food supplements. • From the conversion of 7-dehydro cholesterol in the skin by ultraviolet light to pre Vit- D3 which then slowly equilibrates to Vit- D3

37. 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.

39. 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.

42. Factors affecting Vit D synthesis The amount of Vit D formed by the action of sunlight on the skin is dependent on • Intensity of light • Length of exposure • Skin pigmentation

43. Daily requirement • 400 iu (10ug) of Vit D per day promote optimal calcium absorption and enhance growth • Higher level is recommended for infants and children

44. Daily requirement • With slowing and finally cessation of skeletal growth the daily Vit D allowance decreases to 300 i.u. (7.5 µg) for ages 19 through 22, & 200 i.u. (5 µg) for the later years. • During pregnancy and lactation the Vit D requirement is increased by 200 i.u. (5 µg) to allow for transfer across placenta and into breast milk

45. Recommended Dietary Allowances Infants 0 – 0.5 10 g 0.5 – 1.0 10 g Children 1 – 3 10 g 4 – 6 10 g 7 – 10 10 g

46. Recommended Dietary Allowances AdultsMale Female 11 – 14 10 10 15 – 18 10 10 19 – 22 7.5 7.5 23 – 50 5 5 51+ 5 5 Pregnancy + 5 Lactation + 5

47. Functions It is a steroid and functions like other steroid hormones. It is not dietary essential when there is adequate exposure to ultraviolet light • Vit D plays a major role in the regulation of calcium and phosphate metabolism by promoting their intestinal absorption, influencing the process of bone mineralization.

48. Functions • Vit D exerts its anti ricket action by making the intestinal mucosa permeable to calcium and phosphorus and facilitating the active transport of calcium across cell membranes.

49. Effects of deficiency • A deficiency of Vit D causes impaired intestinal absorption of calcium and phosphorus and faulty mineralization of teeth and bones. • Skeletal malformation result from the inability of the softened bone to withstand weight bearing . In children this bone condition is termed rickets.

50. Effects of deficiency Other symptoms of rickets include • Delayed closure of the fontanelles (suture lines in the skull) especially in premature infants • Projection of sternum (pigeon breast). • Spinal curvature. • Bowing of the legs and • Enlargement o the costochondral junction.