Vitamins water & fat Soluble

Vitamins

1. Vitamins

2. Vitamins are organic substances that are essential for carrying out the normal biochemical processes and physiological functions of body. These are non-energy compounds and required in very small quantities. The vitamins generally serve as cofactors for the enzymes required in intermediary metabolism.

3. The main source of vitamins is diet. A balanced diet supplies adequate amounts of vitamins to fulfill the daily requirements. Humans cannot synthesize vitamins in the body except some vitamins such as Vit. D in skin, and Nicotinamide from tryptophan. Lack of particular vitamin leads to specific deficiency syndromes. Vitamin deficiencies occur due to inadequate intake, malabsorption, increased tissue needs, increased excretion, certain genetic abnormalities and drug-vitamin interactions.

4. The vitamins have been broadly divided into two groups: Fat-soluble vitamins: vit. A, vit. D, vit. E and vit.-K. These vitamins are stored by the body, mainly in the liver. Excessive intake of these can lead to toxicity due to accumulation, known as hypervitaminosis. Water-soluble vitamins : vit B complex group, vit. C. These vitamins are least stored and toxicity does not occur. The excess of vitamins are rapidly metabolized and readily excreted in the urine.

5. Vitamers The different chemical forms and precursors of a vitamin are known as Vitamers of that particular vitamin. These vitamers have generally similar molecular structure and show vitamin- activity in a vitamin deficient biological system. All vitamers may not possess equal vitamin potency. Examples of vitamers include cyanocobalamin, hydroxocobalamin, methylcobalamin and 5- deoxyadenosylcobalamin :- which are all vitamers of Vit B 12 and all possess B 12 activity. Similarly, both niacinamide and nicotinic acid are vitamers of vit-B 3 (Niacin).

6. These vitamins need to be activated to their active forms in the body for their actions. The active forms of some of the vitamins are as follows:   Vitamins Active Forms Vitamin-A Retinal(Stored as Retinol) Vitamin-D 1,25 Dihydrocholecalciferol Vitamin- E α-Tocopherol Vitamin- K Napthaquinone Vitamin-C L- Ascorbic acid Vitamin-B1 (Thiamine) Thiamine pyrophosphate Vitamin-B2 (Riboflavin) Flavin-mononucleotide (FMN) Vitamin-B3 (Niacin) Nicotinamide adenine dinucleotide (NAD) Vitamin-B5 (Pantothenic acid) Coenzyme-A Vitamin-B6 (Pyridoxine) Pyridoxal phosphate Vitamin-B9 (Folic acid) Tetrahydrofolate Vitamin-B12 (Cynocobalamine) 5-Methyl cobalamine

7. FAT SOLUBLE VITAMINS

8. Vitamin- A There are various natural forms of Vitamin A (vitamers) such as Retinol (vit A 1 ), Dehydroretinol (vit A 2 ) and Carotenoids. Dietary Sources: Carrot (richest plant source), red cabbage, turnip, spinach, mango etc. are some of the plant sources. Marine fish liver oil such as cod, halibut (richest animal source), fresh water fish, egg yolk, milk, cheese, butter are some of the animal sources.

9. Physiological functions: Essential for proper functioning of Rod cells in the visual cycle; hence the night vision. Vision in the dim light depends upon proper functioning of Rods. Prevents night blindness and Xerophthalmia. Maintenance of normal epithelium all over body. As antioxidants ( vitamin-A,C,E are more potent antioxidants in nature ) and anti cancer properties. Enhances immune functions and prevents recurrent infections like measles, malaria and diarrhoea, etc. In reproduction, for normal spermatogenesis and foetal development. Bone growth in children.

10. Deficiency Symptoms: These are seen when there is a long term deprivation and the stores are depleted. A disturbance in the physiological roles manifests as the deficiency symptoms. Some of the symptoms are: Eye : Xerosis (dryness) of eye, ‘Bitot’s spots’, keratomalacia (softening of cornea), corneal opacities, night blindness (nyctalopia) progressing to total blindness.

11. Epithelium : Dry and rough skin with papules (phrynoderma), hyperkeratinization, atrophy of sweat glands, keratinization of bronchopulmonary epithelium. Increased tendency to urinary stone formation due to shedding of ureteric epithelial lining which acts as a nidus. Immunity : increased susceptibility to infection such as diarrhoea, measles etc. Reproduction : Sterility due to faulty spermatogenesis, abortions, foetal malformations and growth retardation etc.

12. Recommended dietary allowance (RDA) Daily requirement and for prophylaxis of vit A deficiency during infancy, pregnancy, lactation, hepatobiliary diseases, steatorrhoea: 3000–5000 IU/day. Treatment of established vit A deficiency: 50,000–100,000 IU i.m or orally for 1–3 days followed by intermittent supplemental doses. Skin diseases like acne, psoriasis, ichthyosis. Retinoic acid and 2nd or 3 rd generation retinoids are used.

13. Hypervitaminosis-A It can occur due to regular intake of excessive vit-A >100,000 IU /day for more than three weeks. The toxicity symptoms commonly seen are nausea, vomiting, headache (due to increased intracranial tension and also known as Pseudotumor-cerebri ), itching, erythema, dermatitis, exfoliation, hair loss, bone and joint pains, loss of appetite, irritability, etc. Daily intake should not exceed 20,000 IU.

14. Vitamin-A has been included in National Immunization Programme of India. A total 17-lac unit of vitamin-A is supplemented to child. A total of 9 mega doses are to be given from 9 months of age to 5 years. 100,000 IU at 9 months with measles immunization, 200,000 IU at 16-18 months with DPT booster, 200,000 IU every 6 months upto the age of 5 years.

15. Vitamin- D Vitamin D is the collective name given to antirachitic substances found in foods and synthesized in the body and activated by UV radiation. D1: mixture of antirachitic substances found in food—only of historic interest. D2: ergocalciferol or calciferol is made by UV irradiation, eg. ergosterol in plants and also present in irradiated foods such as yeasts, fungi, bread, milk etc.. D3: cholecalciferol synthesized in the skin under the influence of UV rays.

16. Vitamin D2 and D3 undergo two successive hydroxylations: first in the liver to form 25-hydroxy cholecalciferol and second in the proximal tubules of the kidney to form 1,25- dihydroxy cholecalciferol which is the most physiologically active form of the vit-D i.e. calcitriol.

17. Dietary sources: Halibut liver oil (richest source), codfish liver oil, other animals liver oil and synthesis in body as explained above. Physiological functions: Vitamin-D increases absorption of calcium and phosphates from GIT and tubular reabsorption from renal tubules. It increases both serum calcium and calcitonin levels. It increases the bone mineralization and thus bone-mineral-density (BMD) (deficiency leads to rickets in children and osteomalacia in adults).

18. Deficiency Symptoms : Deficiency may occur in cases of malnutrition, poor Sun exposure, intestinal malabsorption , chronic liver disease and chronic renal failure cases. Manifestations may be in the form of: Rickets in children which may present in the form of various bony deformities such as bow legs, bossing of skull, chest deformities etc. Osteomalacia in adults which may present in the form bone tenderness and decreased bone mineral density (BMD) and predisposition to fractures.

19. Recommended dietary allowance (RDA): Prophylactic dose is 400 IU/day and Therapeutic dose of nutritional vit D deficiency is 3000–4000 IU/day. This is given to prevent and treat rickets in children and Osteomalacia in adults. 300,000–600,000 IU can be given orally or i.m. once in 2–6 months. Recommended Daily Allowance if Sun exposure is adequate: Children: 5µgm/day, Adult: 2.5µgm/day, Pregnant/Lactating women: 10µgm/day *1 μg of cholecalciferol = 40 IU of vit D.

20. Hypervitaminosis-D It can occur due to chronic intake of large doses approximately 50,000 IU/day. Manifestations are hypercalcaemia, weakness, fatigue, vomiting, diarrhoea, sluggishness, polyuria, albuminuria, ectopic Ca2+ deposition in soft tissues, blood vessels, parenchymal organs(calcinosis), renal stones or nephrocalcinosis, hypertension, growth retardation in children.

21. Vitamin D preparations: Supplementation is required in many cases. A few preparation of Vit-D are as follows: Calciferol (Ergocalciferol, vit D2) : Filled in gelatin capsules 25,000 and 50,000 IU caps. Cholecalciferol (vit D3) : As granules for oral ingestion and oily solution for i.m. injection. Calcitriol : 0.25–1 μg orally daily or on alternate days Alfacalcidol : It is 1 α-OH D3—a prodrug that is rapidly hydroxylated in the liver to the active form of vit D i.e. 1,25 (OH)2 D3 or calcitriol. Available in cap. form. Calcipotriol is a preparation for local use and useful in the treatment of psoriasis.

22. Vitamin-E There are a number of tocopherols, of which α-tocopherol has the most potent vit-E activity. It is also the most abundant form of vit E. Dietary sources Wheat germ oil is the richest source, others are cereals, nuts, spinach and egg yolk.

23. Physiological functions It is the most powerful antioxidant. It protects the unsaturated lipids in cell membranes from free radical oxidation damage. It plays an important role in preventing the risk of myocardial infarction, Alzheimer disease etc. It has a lipotropic action. It stabilizes RBC membrane and also enhances the use of Vit-A.

24. Deficiency Symptoms: Deficiency of this vitamin may lead to heamolytic anaemia, retinopathy, skeleton myopathy and peripheral neuropathy with spinocerebellar degeneration. Recommended dietary allowance (RDA) The estimated daily requirement of vit. E is 10 mg. *1 mg of α-tocopherol= 1.49 IU of vit E.

25. Some conditions where Vit-E is useful are: G-6-PD deficiency: 100 mg/day In Retrolental fibroplasia, in premature infants exposed to high oxygen concentrations can be reduced by 100 mg/kg/day oral vitamin E. Acanthocytosis: 100 mg /week i.m. Fibrocystic breast disease, nocturnal muscle cramps and intermittent claudications: 400–600 mg/day. Hypervitaminosis-E No toxicity has been reported even with large doses of vit-E for long periods. Some side effects are abdominal cramps, loose motions and lethargy.

26. Vitamin-K Vitamin K (Koagulation vitamin) is essential for the coagulation process. It is not directly involved in the clotting process but required for the synthesis of four clotting factors in the liver cell: Factor II,VII,IX and X.

27. It occurs naturally in two forms: Phylloquinone (K 1 ) from plant source and Menaquinone (K 2 ) which is synthesized by colonic bacteria (E. coli) in the colon. K 3 is the synthetic form and is available as Fat-soluble forms (Menadione, Acetomenaphthone) and water-soluble forms (Menadione sod. Bisulfate and Menadione sod. Diphosphate).

28. Dietary sources: Green leafy vegetables such as cabbage, spinach and liver, cheese, cereals, nuts, and egg yolk etc. Wheat germ oil is the richest source. Physiological functions: Vit-K is essential for formation of clotting factor-II, VII, IX, X, protein-C & S.

29. Deficiency Symptoms Vit-K is only temporarily concentrated in liver and this store can be exhausted within one week. The deficiency of vit-K occurs due to liver disease, obstructive jaundice, malabsorption, long-term antimicrobial therapy which alters intestinal flora. The most important manifestation is bleeding tendency due to lowering of the levels of prothrombin and other clotting factors in blood. Haematuria is usually first to occur; sites of bleeding are gastrointestinal tract, nose and under the skin where it presents in the form of haemorrhagic spots.

30. Recommended dietary allowance (RDA) Normal adult requirement is 50–100 μg/day. As it can be synthesized in the colon, even 3–10 μg/day may be sufficient. Some conditions where Vit-K is useful are: For prevention of haemorrhagic disease of the newborn : All newborns specially premature infants have low levels of prothrombin and other clotting factors. Vit K 1 mg i.m. soon after birth has been recommended routinely. Alternatively, 5–10 mg i.m. to the mother 4–12 hours before delivery can be given.

31. Menadione (K3) should not be used for this purpose as patients with G-6-PD deficiency and neonates are especially susceptible. In the newborn menadione or its salts can precipitate kernicterus. As an antidote in overdose of oral anticoagulants. In patients suffering from liver disease (cirrhosis, viral hepatitis) . Patients on prolonged antimicrobial therapy.

32. Patients with obstructive jaundice or malabsorption syndromes (sprue, regional ileitis, steatorrhoea, etc). The therapy given is Vit-K 10 mg i.m./day, or orally along with bile salts for better absorption. Hypervitaminosis-K It has not been reported. Only severe allergic or anaphylactoid reactions can occur with iv injection of vit-K formulations.

33. WATER-SOLUBLE VITAMINS

34. B complex group of vitamins The vitamins of this group all generally found together in the food; hence are collectively termed as vitamin B-complex. Most of these are found in both vegetarian and non-vegetarian sources except vit-B 12 , which is not found in vegetable sources, but is found only in various non-vegetarian sources. The B-complex vitamins have been divided conventionally into three subgroups according to the major functions in which they are involved.

35. These are: Energy forming B-complex vitamins: Vitamin- B1, B2, B3, B5, B6, B7 (Biotin) Hematopoietic B-complex vitamins: Folic acid (Vitamin- B9), B12 Non B complex group: Vit-C or ascorbic acid

36. Thiamine or Vitamin-B1 or Aneurine Dietary sources: Cereals, pulses, nuts, green vegetables, yeasts, egg and meat. It is found in the outer layers of the cereals and is heat labile. Physiological functions Its active form thiamine pyrophosphate acts as a coenzyme in the carbohydrate metabolism. It also plays some role in nerve conduction.

37. Deficiency Symptoms Deficiency is mainly dietary in nature. In addition, raw fish, shellfish, coffee and tea inhibit the absorption of vitamin-B1. Some common manifestations are: Beriberi (acute manifestation of B1 deficiency) Dry Beri-Beri Wet Beri-Beri Mostly involves peripheral nervous system. The common signs and symptoms are: peripheral neuropathy, muscles atrophy, muscles weakness, wrist & foot drop. Mostly involves cardiovascular system. The common signs and symptoms are: tachycardia, oedema, cardiomegaly, high output cardiac failure.

38. The treatment involves i.v./i.m. injection of vitamin-B1 given in a dose of 2-10 mg OD, till the symptomatic improvement occurs. Then treatment is given orally. Infantile beriberi : In this condition, newborn of vitamin-B1 deficient mother presents with signs and symptoms of Beri-Beri. To manage this condition, prophylactically 2-10mg/day Vitamin-B1 is supplemented to pregnant mother or infants.

39. Wernick’s encephalopathy: It is most commonly seen in severe alcoholic individuals. Patient presents with global confusion, ophthalmoplegia and cerebral ataxia and these features combined with psychosis are called Koraskoff’s psychosis . (confabulation) To prevent this condition thiamine is given in a dose of 100 mg/day intravenously. Transketolase (product of HMP shunt) test is done to detect vitamin-B1 deficiency.

40. Recommended dietary allowance (RDA): 1-2 mg/ day. Therapeutic uses: Prophylactically: 2–10 mg daily is given in infants, pregnant women, chronic diarrhoea and patients on parenteral alimentation. Beriberi—100 mg/day i.m. or i.v. till symptoms regress. After it, maintenance doses are given orally. Acute alcoholic intoxication: Thiamine 100 mg is added to each vac of glucose solution infused. In Korsakoff’s psychosis, 100 mg/day is given parenterally. In neurological disorders. Adverse effects Thiamine is nontoxic. Sometimes, hypersensitivity reactions can occur on parenteral injection.

41. Riboflavin or Vitamin-B2 Dietary sources: Dairy milk products, liver, meats, egg, cereals, pulses, yeast, green vegetables and sprouts etc. Physiological functions: Its active form acts as coenzyme in the oxidation-reduction reactions and carbohydrate metabolism.

42. Deficiency Symptoms Ariboflavinosis: The deficiency of vitamin-B 2 usually presents with angular stomatitis, cheilosis, seborrheic dermatitis and geographical ulcer on tongue. For therapeutic purpose in Ariboflavinosis: Riboflavin is given in a dose of 2–20 mg/day oral or parenteral till the symptoms subside. Recommended dietary allowance (RDA): 1-2 mg/ day.

43. Niacin or Vitamin-B3 Dietary sources: Liver, meats, egg, fish,cereals, wholegrains, , nuts etc. Physiological functions: Nicotinic acid is readily converted to its amide which is a component of the coenzyme Nicotinamide-adenine-dinucleotide (NAD) and its phosphate form (NADP) involved in oxidation-reduction reactions involved in cellular respiration, glycolysis and fatty acid oxidation. Nicotinic acid is also a lipid-lowering agent.

44. Deficiency Symptoms Pellagra: A deficiency of Niacin may present with 4 Ds: diarrhoea, dermatitis, dementia and death. Along with these features, anaemia and hypoproteinaemia are also seen. These feature are commonly seen in malnourished and alcoholic individuals . To treat this condition, niacin is given twice daily in a dose of 200 to 500 mg orally. Hartnup’s disease: Another deficiency of Niacin, particularly by tryptophan, which is a precursor of niacin formation. Supplementation of niacin is curative.

45. Recommended dietary allowance (RDA): 15-20 mg/ day. Therapeutic uses: Pellagra treatment: Niacin is given twice daily in a dose of 200 to 500 mg orally. Dyslipidemia: Nicotinic acid also used for managing dyslipidemia in a dose of 250 mg BD to 2.0gm/day in sustained release form or three divided doses. Hartnup’s disease: in which tryptophan transport is impaired, need niacin supplementation.

46. Pantothenic acid or Vitamin-B5 Dietary sources: Liver, meats, egg yolk, fish, cereals, wholegrain, nuts, vegetables, etc. Physiological functions: It is a component of coenzyme-A which functions in carbohydrate, fat, steroid and porphyrin metabolism.

47. Recommended dietary allowance (RDA): 2-7 mg/day. Therapeutic uses: 1. For the treatment of burning foot syndrome, 50-100 mg /day is given. 2. Sometimes it is used to treat postoperative paralytic ileus.

48. Deficiency Symptoms: It has been thought to be one of the causing factor of leg cramps, paraesthesia and flatulence. Burning Foot Syndrome (Nutritional megalalia ) may occur due to deficiency of pantothenic acid and seen in individuals expose to heavy antibiotic therapy or colonic resection or severe malnutrition.

49. Pyridoxine or Vitamin-B6 Pyridoxine, Pyriodoxal and Pyridoxamine are related naturally occurring pyridine compounds that have vit B 6 activity and are vitamers of vit B 6. Dietary sources: Widely distributed in the food products of plant and animal origin such as vegetables, soybean, wholegrain, eggs, liver, meat, etc.

50. Physiological functions: Pyridoxine is converted to its coenzyme form i.e. pyridoxal phosphate. Pyridoxal phosphate dependent enzymes ( transaminases, hydroxylases and decarboxylases ) are involved in synthesis of nonessential amino acids, GABA and aminolevulinic acid (first step in the synthesis of haeme).

51. Deficiency Symptoms: Peripheral neuropathy: Presents with tingling sensations of lower limbs. Isoniazid and OCPs produce a pyridoxine deficiency state. Sideroblastic anaemia: Can be treated by administration of 50–200 mg/day pyridoxine phosphate. Seborrheic dermatitis, glossitis, growth retardation, premenstrual tension, mental confusion, lowered seizure threshold and convulsions. Recommended dietary allowance (RDA): 0.8 mg/1000Kcal (2 mg/ day).

52. Therapeutic uses: Prophylactically in alcoholics, infants and patients with deficiency of other B complex vitamins: 2–5 mg daily. To prevent and treat isoniazid, hydralazine and cycloserine induced neurological disturbances: 10–100 mg/day. To treat mental symptoms in women on oral contraceptives: 50 mg daily. Pyridoxine responsive anaemia may be benefited by large doses of pyridoxine: 50–200 mg/day.

53. Biotin or Vitamin-B7 or vitamin H Biotin is a sulfur containing organic acid found in many food items. Some intestinal bacteria synthesize biotin which is also absorbed. Its deficiency can be caused by eating raw egg white for months to years. Egg white contains a protein named “Avidin” which binds biotin strongly and prevents its absorption. Dietary sources: Liver, egg yolk, meat, nuts are the other source.

54. Physiological functions: Biotin is a coenzyme for five carboxylases in the body and is essential for amino acid catabolism, gluconeogenesis and fatty acid metabolism. It is also essential for gene stability because it is covalently attached to histones. Deficiency Symptoms: Deficiency can occur due to regular raw egg white intake, colonic resection or severe malnutrition or heavy exposure to antibiotics. Symptoms are : anorexia, glossitis, seborrheic dermatitis, alopecia, fatigue and muscular pain. Recommended dietary allowance (RDA): 0.2 mg /day. Therapeutic dose in case of deficiency symptoms is 10-20 mg /day.

55. Folic acid or Vitamin-B9 In 1941, Mitchell isolated an antianaemia principle from spinach and called it ‘folic acid’ (from leaf). Folic acid is present in the food as polyglutamates. Each folic acid molecule may have 2-8 molecules of glutamic acid. Dietary sources: Green leafy vegetables(spinach), Liver, egg, meat, milk. It is also synthesized by gut flora, but this is largely unavailable for absorption.

56. Physiological functions: Folic acid is inactive as such and is reduced to the coenzyme form in two steps: FA is converted to DHFA by by folate reductase (FRase) and then to THFA by dihydrofolate reductase (DHFRase). THFA mediates a number of one carbon transfer reactions which are essential in the synthesis of purines and pyrimidines. These purines and pyrimidines are essential in DNA synthesis.

57. Deficiency Symptoms: These can occur due to dietary deficiency, malabsorption syndrome, excessive demand, liver diseases or drug induced. The manifestations are: Megaloblastic anaemia Neural tube defects: Neural tube defects, including spina bifida in the offspring, due to maternal folate deficiency. This can be prevented by administration of folic acid started 3 month before conception till 1 st trimester followed by iron with calcium. Epithelial damage: Glossitis, enteritis, diarrhoea, steatorrhoea.etc. General debility, weight loss, sterility.

58. Recommended dietary allowance (RDA): Dose: 2 to 5 mg/day, prophylactic 0.5 mg/day. Therapeutic uses: Megaloblastic anaemias, Nutritional folate deficiency, Increased demand: pregnancy, lactation, infancy, during treatment of severe iron deficiency anaemia, haemolytic anaemias. Pernicious anaemia. Malabsorption syndromes: Tropical sprue,coeliac disease, idiopathic steatorrhoea, etc. Antiepileptic therapy: patients on prolonged phenytoin/phenobarbitone therapy Prophylactic of folate deficiency: during pregnancy to prevent neural tube defects in foetus.

59. Vitamin-B 12 Cyanocobalamin and hydroxocobalamin are complex cobalt containing compounds present in the diet and referred to as vit-B 12 . Dietary sources Richest source is liver, which contains large deposite of vitamin-B12 and that is sufficient for 2-5 years. Other sources are kidney, sea fish, egg yolk, meat, cheese. The only vegetable source is legumes (pulses) which get it from microorganisms harboured in their root nodules. Vit B12 is synthesized by the colonic microflora, but this is not available for absorption in man. The commercial source is Streptomyces griseus. Animal food product contain higher amount of Cynocobalamine than plant products.

60. Physiological functions: Vit-B12 is intricately linked with folate metabolism. The active coenzyme forms of B12 generated in the body are deoxy-adenosyl-cobalamin (DAB12) and methyl-cobalamin (methyl B12). It links the carbohydrate and lipid metabolisms. It is needed in the synthesis of phospholipids and myelin sheath . Vit-B12 is essential for cell growth and multiplication. Deficiency Symptoms: Vitamin-B12 deficiency may occur due to strict vegetarian diet, pernicious anaemia, severe malabsorption, surgical resection of terminal ileum or stomach.

61. Deficiencies of vitamin-B12 manifest as : Megaloblastic anaemia. Subacute combined degeneration of spinal cord (SACD). Peripheral neuritis which usually presents with loss of fine touch, vibration and proprioception, paresthesias and depressed stretch reflexes. If these features are present with psychosis, it is called Megaloblastic madness . To prevent this condition administer 1000µgm vitamin-B12 weekly for 8 weeks. Glossitis, GI disturbances and damage to epithelial structures. Recommended dietary allowance (RDA): Adult- 1-3 µgm/day, pregnancy and lactation 3–5 μg/day.

62. Therapeutic uses Treatment of vit-B12 deficiency: vit B12 is used alongwith 1–5 mg of oral folic acid and an iron preparation to get best results. Prophylaxis : when there are definite predisposing factors for development of deficiency. Tobacco amblyopia: hydroxocobalamin provides some benefit by trapping cyanide derived from tobacco to form cyanocobalamin. Mega doses of vit B12 have been used in neuropathies, psychiatric disorders, cutaneous sarcoid and as a general tonic to allay fatigue, improve growth. The value of these uses is questionable. Adverse effects: Even large doses of vit-B12 are quite safe. Allergic reactions have occurred on injection, probably due to contaminants. It should never be used by IV route.

63. Vitamin- C Ascorbic acid is an organic acid with structural similarity to glucose. It is a potent reducing agent and l -form is biologically active. Vitamin-C is sensitive to heat. Dietary sources: Citrus fruits (lemons, oranges), black currants, crane berry, ley berry, guava, tomato, leafy vegetables, sprouts, mango and green chilies. Breast milk contain more vit-C than cow’s milk. Indian gooseberry (Amla) is the richest source of vitamin- C.

64. Physiological functions: Vit-C plays important role in many oxidative and other metabolic reactions. It is essential for the formation and stabilization of collagen. Therefore, it plays essential role in tissue repair and formation of cartilage, bone and teeth. It acts as an antioxidant, improves immunity and prevents cataract formation also. It plays an important role in absorption of iron and conversion of folic acid to folinic acid; therefore helps in RBC production [erythropoiesis]. It plays an important role in biosynthesis of adrenal steroids, catecholamines, oxytocin, vasopressin and bile acid.

65. Deficiency Symptoms: Scurvy [swollen and bleeding gums], Delayed wound healing, anemia, growth retardation, brittle bones, etc. Recommended dietary allowance (RDA): 40-60mg/day.

66. Therapeutic uses: Prophylactic dose : In deficiency susceptible individuals] is 50-100 mg daily. Therapeutic dose in scurvy treatment is 500-1500 mg/day. To acidify urine in UTI treatment: 1 gm TDS. Anaemia: To enhance the iron absorption [500 mg BD; along with iron tablets]. To improve immunity and wound & fracture healing after surgery, injury, etc given in a dose of 500 mg daily along with Zinc. Adverse effects: Renal oxalate stone formation can occur when higher doses are taken for longer durations.