Vitamin C

INTRODUCTION OF VITAMIN “C”

·         Vitamin c also known as ascorbic acid.

·         First isolated in 1928, vitamin C was identified as the curative agent for scurvy in 1932.

·         They are water soluble.

·         Ascorbic acid is an enediol-lactone of an acid with a configuration similar to that of the sugar L-glucose.

·         It is an essential nutrient in many multicellular organisms, especially in humans.

·         Naturally occurring vitamin C is L-Ascorbic acid.

·         Required for growth & development.

·         Does not store in the body.

·         Vitamin C sources come from diet.

·         It is stable in solid form and in acidic solutions, but is rapidly destroyed in alkaline solutions. Oxidative destruction of ascorbic acid is accelerated by increasing pH.

BIOSYNTHESIS:

Ø  Some lower mammals like rats can synthesize the vitamin from glucose by the uronic acid pathway.

Ø  Man, monkey and guinea pigs lack the enzymes necessary for the synthesis. They cannot convert ketogulonolactone to ascorbic acid. Hence the entire human requirement must consequently be supplied by the diet

CHEMICAL NAME OF VITAMINN 

(5R)-[(1S)-1,2-Dihydroxyethyl]-3,4-dihydroxyfuran-2(5H)-one.

STRUCTURE OF VITAMIN C :

Vitamin C has the chemical formula C6H8O6 and a molecular mass of 176.14 grams per mol. Vitamin C is purely the L-enantiomer of ascorbate; the opposite D- enantiomer has no physiological significance. Both forms are mirror images of the same molecular structure.

DIETARY SOURCES OF VITAMIN C

These are chiefly vegetable sources. Good sources are citrousfruits : orange, lemon, lime etc; other fruits like papaya, pineapple, banana, strawberry. Amongst vegetables ; leafy vegetables like cabbage & cauliflower, germinating seeds, green peas & beans, potatoes & tomatoes. Amla  is the richest source.

Considerable amount of vitamin C activity is lost during cooking, processing and storage, because of its water-solubility and its irreversible oxidative degradation to inactive compounds.

RECOMMENDED  INTAKE  OF VITAMIN C

PHYSIOLOGICAL ROLE OF VITAMIN C

·         PROTEIN SYNTHESIS:Vitamin C is the normal synthesis of collagen, L-carnitine, catecholamines, and proteins. It acts as a cofactor to the mixed function oxidase enzymes which catalyze these chemical pathways. Vitamin C donates electrons readily to eight enzymes in the human body. Three of these are involved in the biosynthesis of collagen.

·         ANTIOXIDANT  ACTIVITY: Important role of vitamin C  is antioxidant role. It is a powerful reducing agent, and therefore readily takes place in redox reactions, shifting between the two forms ascorbic acid &dehydroascorbic acid.

·         IMMUNE REGULATION: A third function of vitamin C is its role in immune regulation. Vitamin C stimulates phagocytosis as well as antibody formation.

·         IRON ABSORPTION: Vitamin C enhances the absorption of non-heme iron, which is the type present in plant foods, in the intestine.

·         BILE ACID SYNTHESIS: Vitamin C stimulates the initial step in cholesterol metabolism to bile acids. This function may have importance in the formation of gallstones and the maintenance of normal blood cholesterol levels.

·         SEROTININ PRODUCTION: Vitamin C is also essential for the synthesis of serotonin, during which it hydroxylates the amine tryptophan to 5- hydroxyl tryptophan.

·         ADRENAL STEROID SYNTHESIS: Vitamin C is present in relatively high concentration in the adrenal cortex, but the levels go down after ACTH stimulation of the gland. This implies that vitamin C has a part to play in the synthesis of adrenal steroids.

MECHANISM OF ACTION OF VITAMIN C

In humans, an exogenous source of ascorbic acid is required for collagen formation and tissue repair by acting as a cofactor. Ascorbic acid is reversibly oxidized to dehydroascorbic acid in the body. These two forms of the vitamins are believed to be important in oxidation reduction reactions. The vitamin is involved in tyrosine metabolism, conversion of folic acid to folinic acid, carbohydrate metabolism, synthesis of lipids & proteins, iron metabolism, resistance to infections and cellular respiration.

It is absorbed readily from the small intestine, peritoneum and subcutaneous tissues. It is widely distributed throughout the body. Some tissues contain high concentrations as compared to others. Local concentration roughly parallels the metabolic activity, found in descending order as follows; Pituitary gland, adrenal cortex, corpus luteum, liver, brain,  gonads, thymus, spleen, kidney, heart, skeletal muscle etc.

Ø  Normal human blood plasma: it contains approx., 0.6 to 1.5 mg of ascorbic acid per 100 ml.  

DEFICIENCY DISORDERS OF VITAMIN C

Deficiency or a lack of vitamin C in your body happens because of a lack of sufficient amounts of vitamin C in your diet. A lack of vitamin C means that new collagen cannot be formed. This causes various tissues in your body to start to breakdown and the health and repair of your body become affected. Persistent ( chronic ) vitamin C deficiency, usually over a period of around three months or more, can lead to an illness known as scurvy.

Ø REASON FOR DEFICIENCY OF VITAMIN C:

   

 The reason for deficiency of vitamin C or ascorbic acid is scurvy. The deficiency leads to symptoms of weakness, anemia, gum disease, and skin problems.

       This is because vitamin C is needed for making collagen, an important component in connective tissues. Connective tissues are essential for structure and support in the body, including the structure of blood vessels.

        A lack of vitamin C will also affect the immune system, absorption of iron, metabolism of cholesterol and other functions.  

SYMPTOMS OF DEFICIENCY OF VITAMIN C

Ø  ROUGH, BUMPY SKIN: Vitamin C deficiency can the formation of small acne like bumps on the arms, thighs and buttocks.

Ø  CORKSCREW-SHAPED BODY HAIR:Abnormally bent, coiled or corkscrew shaped body hairs are a hallmark sign of vitamin C deficiency, but they may be difficult to detect, as these hairs are more likely to fall out.

Ø  SLOWLY HEALING WOUNDS:Vitamin C deficiency interferes with tissue formation, causing wounds to heal more slowly.

Ø  WEAK BONES: Vitamin C  is important for bone formation, and deficiency can increase the risk of developing weak and brittle bones.

Ø  BLEEDING GUMS AND TOOTH LOSS: Red, bleeding gums are a common sign of vitamin C deficiency, and severe deficiency can even lead to tooth loss.

Ø  PERSISTENT IRON DEFICIENCY ANEMIA: Vitamin C deficiency may increase the risk of iron deficiency anemia by reducing iron absorption and increase of bleeding.

Ø  UNEXPLAINED WEIGHT GAIN: Low vitamin C intake has linked to increase body fat in humans, but other factors may be involved, such as diet quality.

TREATMENT FOR DEFICIENCY OF VITAMIN C

Treatment involves administering vitamin C supplements by mouth or by injection.

The recommended dosage is :

·         1 to 2 grams (g) per day for 2 to 3 days.

·         500 milligrams (mg) for the next 7 days.

·         100 mg for 1 to 3 months.

·         Within 24 hours, patients can expect to see an improvement in fatigue, lethargy, pain, anorexia and confusion. Bruising, bleeding and weakness start to resolve within 1 to 2 weeks.

REFERENCES;

·         Mn Chatterjee (Book Of Biocemistry)

·         Principles of Biochemistry Albert L. Lehninger

·         Google Source (Http://Www.Jhrr.Org)

·         Https://Www.Amboss.Com/Us/Knowledge/Vitamins

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