Role of Vitamin C in Body Health

 

Shrada. B. Kumar¹, Dr. Dhanraj. M²

¹CRI, Saveetha Dental College,  Saveetha University, Chennai.

²Professor, Department of Prosthodontics, Saveetha Dental College,  Saveetha University, Chennai.

 

ABSTRACT:

Vitamins and minerals are usually needed in very minute quantities. But their presence is necessary for the normal physiological functions of the body. One such important vitamin is vitamin C which is usually seen in citrus fruit. It is their deficiency which causes scurvy. Their physiological functions have been discussed. Their important properties is also been told here. Their sources, deficiency symptoms are also been told. It also says about their chemical structure and history. Vitamin has a lot of properties which are very useful in the well being of an individual. Yet it has some disadvantages which we are unaware of. Few such disadvantages are also being discussed here. Not that vitamin C could be consumed at any time. There conditions in which one is not supposed to take vitamin C supplements. All such conditions are been discussed.

 

 

 

INTRODUCTION:

Vitamin C is a ‘water-soluble’ vitamin, which cannot be produced in our body (due to lack of gulonolactone oxidase). The recommended daily allowance (RDA) for vitamin C ranges between 100–120 mg/per day for adults. It is present in fruits like orange, lemons, grapefruit, watermelon, papaya, strawberries, cantaloupe, mango, pineapple, raspberries and cherries. It is also found in green leafy vegetables, tomatoes, broccoli, green and red peppers, cauliflower and cabbage. The synthetic sources of this vitamin are tablets, capsules, liquid form, crystalline powder and chewable tablets. This vitamin is rich in anti oxidants. (1-4)

 

HISTORY:

Vitamin C was discovered in 17^th century, the exact role of this vitamin in human biology and health is still a mystery in view of many beneficial claims and controversies.

 

Ascorbic acid was isolated from natural sources. Structurally characterized by Szent-Gyorgyi, Waugh and King. This vitamin was first synthesized by Haworth and Hirst. (5, 6)

 

SOURCES:

Birds and animals have the capacity to biosynthesize ascorbic acid with the help of enzymes present in kidney and liver. (7, 8) However, species such as teleost fish, some passeriform birds, guinea pigs, and some primates like humans, have lost the ability to synthesize ascorbic acid. This inability to synthesize ascorbic acid is due to the lack of L-gulonolactone oxidase, which is highly mutated in human beings. (9,10)

 

CHEMISTRY:

L-ascorbic acid (C₆H₈O₆) is the common name of Vitamin C. The chemically it is 2-oxo-L-threo-hexono-1, 4-lactone-2, 3-enediol. L-ascorbic and dehydroascorbic acid are the major dietary forms. Loss of ascorbic acid on cooking depends on degree of heat, surface exposure of water, pH, oxygen and presence of transistion metals. Ascorbic acid is more stable between pH 4 and 6.(11)

 

 

PYSIOLOGICAL FUNCTIONS:

The oxido-reduction property of this vitamin determines the physiological functions of ascorbic acid. L-ascorbic acid is a co-factor for hydroxylases and monooxygenase enzymes involved in the synthesis of collagen, carnitine and neurotransmitters (12). By maintaining the active center of metal ions in a reduced state for optimal activity of enzymes hydroxylase and oxygenase ascorbic acid accelerates hydroxylation reactions. Ascorbic acid plays role in the maintenance of collagen which is about one third of the total body protein. It constitutes the principal protein of skin, bones, teeth, cartilage, tendons, blood vessels, heart valves, inter vertebral discs, cornea and eye lens. The hydroxylation of proline and lysine is carried out by the enzyme prolyl hydroxylase with ascorbic acid as co-factor. Deficiency of ascorbic acid, results in reduced hydroxylation of proline and lysine, affecting the collagen synthesis. Ascorbic acid is essential for the synthesis of muscle carnitine (β-hydroxy butyric acid) (13), which is required for transport and transfer of fatty acids into mitochondria where it can be used for energy production. Ascorbic acid acts as co-factor for hydroxylations involved in carnitine synthesis.

 

SOURCES AND DIETARY RECOMMENDATION:

Recommended dietary allowances (RDA) for adults are 90 mg/day for men and 75 mg/day for women (14). Consumption of 100 mg/day of ascorbic acid is found to be sufficient to saturate the body pools (neutrophils, leukocytes and other tissues) in healthy individuals. However, smokers are suggested of daily intake of minimal 140mg/day as compared to the 100mg/day of non-smokers; in order maintain cellular saturation and optimum risk reduction of heart disease, stroke and cancer in healthy individuals. (15)

 

ROLE OF VITAMIN C:

Common cold:

The role of vitamin C in common cold is controversial. During cold ascorbic acid is seen not to show any prophylactic effect. It is only seen to decrease the severity. The role of ascorbic acid involved in T-cell, capable of lysing infected targets by producing large quantities of cytokines and by helping B cells to synthesize immunoglobulins to control inflammatory reactions, proliferation in response to infection. Further, it has been shown that ascorbic acid blocks pathways that lead to apoptosis of T-cells and thus stimulate or maintain T cell proliferation to attack the infection. (16, 17)

 

Wound healing:

Vitamin C is essential for wound healing because of its property of collagen synthesis. Hence vitamin C is given to patients in post-operative conditions for synthesis of collagen at the site of wound. Administration of 500mg to 1g of the vitamin C is required for accelerated healing. (18)

 

Heart diseases:

Vitamin C is used to prevent heart attack or stroke. It does not reduce the cholesterol level ,it prevents the oxidation of LDL cholesterol which may build plaque in arteries and cause stroke. It is also seen that vitamin C helps to keep the arteries flexible. Moreover it is seen that people who have reduced vitamin C level are seen to develop heart attack ,stroke and peripheral artery diseases. (19-22)

 

Cancer:

Studies show that the incidence of cancer (skin cancer, cervical dysplasia and breast cancer) is low in people taking vitamin C. But the vitamin is not seen to show any therapeutic effect. (23-25)

 

Other properties:

·        Maintains healthy gums.

·        Decreasing blood sugar in people with diabetes

·        Reducing effects of sun exposure

 

DEFICIENCY SYMPTOMS:

Deficiency of the vitamin leads to dry and splitting hair; gingivitis  and bleeding gums, rough, dry, scaly skin, decreased wound-healing rate, and a decreased ability to ward off infection. A severe form of vitamin C deficiency is known as scurvy.

 

PRECAUTIONS:

Vitamin C has its own side effects. It is advisable to take vitamin C supplements as prescribed by doctors. Since vitamin C has diuretic effect it is advisable to drink plenty of water. It also increases the amount of iron absorbed from food, so people with hemochromatosis should not take vitamin C supplements. People with kidney problem must talk to their doctor before taking vitamin C. Excessive consumption may lead to stomach upset. This vitamin may interfere in the healing. If you are medications like aspirin ,warfarin, tetracycline, oral contraceptive, protease inhibitor, chemotherapy drugs, etc.., it is better to ask your doctor before consuming vitamin C supplements.

 

CONCLUSION:

Vitamin C is one of the essential and most important vitamin in human body. It is essential for various physiological functions of our body due to its various properties. Although its discovery dates back to 17^th century many of its functions are not completely understood and remain controversial.

 

 

REFERENCE:

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3.       WHO Model Formulary 2008 (PDF). World Health Organization. 2009. p. 496. ISBN 9789241547659. Retrieved 8 December 2016.

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5.       Waugh WA, King CG: Isolation and identification of vitamin C. J Biol Chem. 1932, 97: 325-331.

6.       Haworth WN, Hirst EL: Synthesis of ascorbic acid. J Soc Chem Ind (London). 1933, 52: 645-647

7.       Grollman A. P., Lehninger A. L. (1957). Enzymic synthesis of L-ascorbic acid in different animal species. Arch. Biochem. Biophys. 69, 458–467. 10.1016/0003-9861(57)90510-6

8.       Nishikimi M., Yagi K. (1991). Molecular basis for the deficiency in humans of gulonolactone oxidase, a key enzyme for ascorbic acid biosynthesis. Am. J. Clin. Nutr. 54, 1203S–1208S.

9.       Nishikimi M., et al (1994). Cloning and chromosomal mapping of the human nonfunctional gene for L-gulono-gamma-lactone oxidase, the enzyme for L-ascorbic acid biosynthesis missing in man. J. Biol. Chem. 269, 13685–13688.

10.     Valpuesta V., Botella M. A. (2004). Biosynthesis of L-ascorbic acid in plants: new pathway for an old antioxidant. Trends Plant Sci. 9, 573–577. 10.1016/j.tplants.2004.10.002

11.     Moser U, Bendich A: Vitamin C. In: Handbook of Vitamins. Edited by: Machlin LJ. 1990, Marcel Dekker, New York, Ch5-

12.     Levin M: New concepts in the biology and biochemistry of ascorbic acid. New Engl J Med. 1986, 31: 892-902.

13.     Hulse JD ,et al: Carnitine biosynthesis-beta hydroxylation of trimethyllysine by an α-keto glutarate dependent mitochondrial dioxygenase. J Biol Chem. 1978, 253: 1654-1659.

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16.     Douglas RM,et al: Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2000, 2: CD000980-

17.     Campbell JD, et al AT: Ascorbic acid is a potent inhibitor of various forms of T cell apoptosis. Cell Immunol. 1999, 194: 1-5. 10.1006/cimm.1999.1485.

18.     Steinbrecher UP, et al: Role of oxidative modified LDL in atherosclerosis. Free Rad Biol Med. 1990, 9: 155-168. 10.1016/0891-5849(90)90119-4.

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20.     Berger TM, et al: Antioxidant activity of viamin C in iron-over loaded human plasma. J Biol Chem. 1992, 272: 15656-15660. 10.1074/jbc.272.25.15656.

21.     Frei B,et al: Ascorbate is an outstanding antioxidant in human blood plasma. Proc Natl Acad Sci USA. 1989, 86: 6377-6381.

22.     Martin A, Frei B: Both intracellular and extracellular vitamin C inhibit atherogenic modification of LDL by human vascular endothelial cells. Atheroscler Thromb Vasc Biol. 1997, 17: 1583-1590

23.      Pauling L, et al: Supplemental ascorbate in the supportive treatment of cancer: Prolongation of survival times in terminal human cancer. Proc Natl Acad Sci USA. 1976, 73: 3685-3689.

24.     Cameron E, Pauling L: Supplemental ascorbate in the supportive treatment of cancer: Reevaluation of prolongation of survival times in terminal human cancer. Proc Natl Acad Sci USA. 1978, 75: 4538-4542.

25.     Murata A, Morsige F, Yamaguchi H: Prolongation of survival times of terminal cancer patients by administration of large doses of ascorbate. Int J Vit Nutr Res Suppl. 1982, 23: 103-113.

 

 

 

Accepted on 28.12.2017        © RJPT All right reserved

Research J. Pharm. and Tech 2018; 11(4): 1378-1380.