Vitamin c

vitamin c, sources, functions,deficiency

1. VITAMIN C or ASCORBIC ACID

2. Functions Clinical features & morphology of scurvy Vitamin C

3. Water soluble vitamin 70 percentage of vitamin C is lost in the process of cooking Most animals & plants can synthesize ascorbic acid from glucose Man, higher primates, guineapigs & bats cannot synthesize ascorbic acid

4. Dietary sources of vitamin C Amla ( Indian gooseberry- 700 mg/100 g) Guava, lime, lemon Green leafy vegetables Milk & Animal products like liver & fish

5. Functions of vitamin C

6. 1. It can change between ascorbic acid & dehydroascorbic acid Most physiological properties of vitamin are explained by this redox system

7. 2 . Ascorbic acid is necessary for the post transilational hydroxylation of proline & lysine residues Hydroxy proline & hydroxy lysine form cross links in collagen- gives tensile strength to fibers This process is necessary for the normal production of supporting tissues like osteoid, collagen, and intercellular cement substances o f capillaries

8. 3 . Tryptophan metabolism Hydroxylation of tryptophan to 5-hydroxy tryptophan- formation of serotonin

9. 4 . Tyrosine metabolism Oxydation of parahydroxyphenylpyruvate to homogenitisic acid

10. 5 . Iron metabolism Vit C reduces ferric iron to ferrous state, which is preferentially absorbed from intestine

11. 6 . Hemoglobin metabolism Reconversion of met-hemoglobin to hemoglobin

12. 7 . Folic acid metabolism Helps the enzyme folate reductase to reduce foluc acid to tetrahydrofolic acid Thus helps in maturation of RBC

13. 8 . Steroid synthesis Has some role in adrenal steroidogenesis Vit C is present in adrenal cortex- depleted by ACTH stimulation

14. 9 . Stimulates phagocytic action of WBC

15. 10 . Vit C is concentrated in the lens of eye Regular intake of vit C reduces risk of cataract formation

16. 11 . Antioxidant property Ability to scavenge free radicals directly Participate in metaboluc reactions that regenerate antioxidant form of vit E

17. CLINICAL FEATURES & MORPHOLOGY OF SCURVY

18. Gross deficiency of vit C Characterised by bone diseases in growing children & by hemorrhages & healing defects in both children & adults

19. SYMPTOMS OF SCURVY Symptoms of scurvy generally develop after 3 months of severe or total vit C deficiency, they include; Wekness & fatigue Bruising easily & bleeding from weakened blood vessels, conn: tissue & bones due to collagen loss Hair & teeth loss Gingivitis: gums become painful, swollen & spongy

20. Infantile scurvy (Barlow's disease): infants have pain when they move & lose their appetite. Infants do not gain weight as they normally do In infants & children bone growth is impaired & bleeding & anemia may occur In infants between 6 to 12 months of age diet should be supplemented with vitamin C sources

21. Hemorrhagic tendency: collagen is abnormal & intercellular cement substance is brittle. So capillaries are fragile, bleed under minor pressure Subcutaneous hemorrhage manifested as petechiae in mild deficiency & as ecchymoses or hematoma in severe conditions In severe cases hemorrhage may occur in the conjunctiva & retina.

22. In bones, deficiency results in failure of osteoblast to form the intercellular ground substance osteoid The resulting scorbutic bone is weak & fractures easily Hemorrhage into joint cavity lead to painful swelling of the joint

23. Microcytic hypochromic anemia is seen Poikilocytosis & anisocytosis are also common Reason for anemia may be: -loss of blood by hemorrhage -decreased iron absorption -decreased THFA

24. OBESITY

25. Obesity Pathogenesis Metabolic changes

26. Obesity is defined as a state of increased body weight, due to adipose tissue accumulation, that is of sufficient magnitude to produce adverse health effects One method to measure fat accumulation is to find the Body Mass Index(BMI) BMI- (wt in kg)/ (height in meters)2 Normal range- 18 to 25 kg/m2 25-30-overweight, greater than 30 kg/m2-obesity

27. Obesity results when- -calorie intake exceeds utilisation -lnactivity & sedentary lifestyle -genetic predisposition -diseases like hypothyroidism & cushing's disease

28. PATHOGENESIS Adipose mass is increased due to enlargement of adipose cells due to excess lipid deposition & increase in number of adipocytes Excess consumption of nutrients

29. MORPHOLOGIC FEATURES Increased adipose stores in subcutaneous tissues, skeletal muscles & internal organs like kidneys, heart, liver & omentum Fatty liver is more common

30. MATABOLIC CHANGES 1 . Hyperinsulinemia Hyperglycemia due to a state of insulin resistance 2 . Type 2 DM Obesity exacerbate the diabetic state

31. 3 . Hypertension Due to increased blood volume 4 . Hyperlipoproteinemia Normally plasma cholesterol circulates in blood as LDL Obesity associated with VLDL & mildly with LDL

32. 5 . Atherosclerosis Risk of MI & stroke 6 . Nonalcoholic fatty liver May progress to cirrhosis 7 . Cholilithiasis 8 . Hypoventilation syndrome (pickwickian syndrome)

33. 9 . Osteoarthritis Due to wear & tear following trauma to joints 10 . Cancer

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